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![Jens Axboe](/assets/img/avatar_default.png)
Currently we look it up from ->ioprio, but ->ioprio can change if either the process gets its IO priority changed explicitly, or if cfq decides to temporarily boost it. So if we are unlucky, we can end up attempting to remove a node from a different rbtree root than where it was added. Fix this by using ->org_ioprio as the prio_tree index, since that will only change for explicit IO priority settings (not for a boost). Additionally cache the rbtree root inside the cfqq, then we don't have to add code to reinsert the cfqq in the prio_tree if IO priority changes. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2676 lines
64 KiB
C
2676 lines
64 KiB
C
/*
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* CFQ, or complete fairness queueing, disk scheduler.
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*
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* Based on ideas from a previously unfinished io
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* scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
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*
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* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
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*/
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#include <linux/module.h>
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#include <linux/blkdev.h>
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#include <linux/elevator.h>
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#include <linux/rbtree.h>
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#include <linux/ioprio.h>
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#include <linux/blktrace_api.h>
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/*
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* tunables
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*/
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/* max queue in one round of service */
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static const int cfq_quantum = 4;
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static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
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/* maximum backwards seek, in KiB */
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static const int cfq_back_max = 16 * 1024;
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/* penalty of a backwards seek */
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static const int cfq_back_penalty = 2;
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static const int cfq_slice_sync = HZ / 10;
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static int cfq_slice_async = HZ / 25;
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static const int cfq_slice_async_rq = 2;
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static int cfq_slice_idle = HZ / 125;
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/*
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* offset from end of service tree
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*/
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#define CFQ_IDLE_DELAY (HZ / 5)
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/*
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* below this threshold, we consider thinktime immediate
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*/
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#define CFQ_MIN_TT (2)
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#define CFQ_SLICE_SCALE (5)
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#define CFQ_HW_QUEUE_MIN (5)
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#define RQ_CIC(rq) \
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((struct cfq_io_context *) (rq)->elevator_private)
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#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
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static struct kmem_cache *cfq_pool;
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static struct kmem_cache *cfq_ioc_pool;
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static DEFINE_PER_CPU(unsigned long, ioc_count);
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static struct completion *ioc_gone;
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static DEFINE_SPINLOCK(ioc_gone_lock);
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#define CFQ_PRIO_LISTS IOPRIO_BE_NR
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#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
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#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
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#define sample_valid(samples) ((samples) > 80)
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/*
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* Most of our rbtree usage is for sorting with min extraction, so
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* if we cache the leftmost node we don't have to walk down the tree
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* to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
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* move this into the elevator for the rq sorting as well.
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*/
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struct cfq_rb_root {
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struct rb_root rb;
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struct rb_node *left;
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};
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#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, }
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/*
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* Per block device queue structure
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*/
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struct cfq_data {
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struct request_queue *queue;
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/*
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* rr list of queues with requests and the count of them
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*/
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struct cfq_rb_root service_tree;
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/*
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* Each priority tree is sorted by next_request position. These
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* trees are used when determining if two or more queues are
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* interleaving requests (see cfq_close_cooperator).
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*/
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struct rb_root prio_trees[CFQ_PRIO_LISTS];
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unsigned int busy_queues;
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/*
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* Used to track any pending rt requests so we can pre-empt current
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* non-RT cfqq in service when this value is non-zero.
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*/
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unsigned int busy_rt_queues;
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int rq_in_driver;
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int sync_flight;
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/*
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* queue-depth detection
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*/
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int rq_queued;
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int hw_tag;
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int hw_tag_samples;
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int rq_in_driver_peak;
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/*
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* idle window management
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*/
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struct timer_list idle_slice_timer;
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struct work_struct unplug_work;
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struct cfq_queue *active_queue;
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struct cfq_io_context *active_cic;
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/*
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* async queue for each priority case
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*/
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struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
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struct cfq_queue *async_idle_cfqq;
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sector_t last_position;
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unsigned long last_end_request;
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/*
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* tunables, see top of file
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*/
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unsigned int cfq_quantum;
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unsigned int cfq_fifo_expire[2];
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unsigned int cfq_back_penalty;
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unsigned int cfq_back_max;
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unsigned int cfq_slice[2];
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unsigned int cfq_slice_async_rq;
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unsigned int cfq_slice_idle;
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struct list_head cic_list;
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};
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/*
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* Per process-grouping structure
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*/
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struct cfq_queue {
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/* reference count */
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atomic_t ref;
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/* various state flags, see below */
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unsigned int flags;
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/* parent cfq_data */
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struct cfq_data *cfqd;
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/* service_tree member */
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struct rb_node rb_node;
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/* service_tree key */
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unsigned long rb_key;
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/* prio tree member */
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struct rb_node p_node;
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/* prio tree root we belong to, if any */
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struct rb_root *p_root;
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/* sorted list of pending requests */
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struct rb_root sort_list;
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/* if fifo isn't expired, next request to serve */
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struct request *next_rq;
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/* requests queued in sort_list */
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int queued[2];
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/* currently allocated requests */
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int allocated[2];
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/* fifo list of requests in sort_list */
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struct list_head fifo;
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unsigned long slice_end;
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long slice_resid;
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unsigned int slice_dispatch;
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/* pending metadata requests */
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int meta_pending;
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/* number of requests that are on the dispatch list or inside driver */
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int dispatched;
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/* io prio of this group */
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unsigned short ioprio, org_ioprio;
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unsigned short ioprio_class, org_ioprio_class;
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pid_t pid;
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};
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enum cfqq_state_flags {
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CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
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CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
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CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
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CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
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CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
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CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
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CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
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CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
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CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
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CFQ_CFQQ_FLAG_sync, /* synchronous queue */
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CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */
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};
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#define CFQ_CFQQ_FNS(name) \
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static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
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{ \
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(cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
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} \
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static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
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{ \
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(cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
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} \
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static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
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{ \
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return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
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}
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CFQ_CFQQ_FNS(on_rr);
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CFQ_CFQQ_FNS(wait_request);
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CFQ_CFQQ_FNS(must_dispatch);
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CFQ_CFQQ_FNS(must_alloc);
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CFQ_CFQQ_FNS(must_alloc_slice);
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CFQ_CFQQ_FNS(fifo_expire);
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CFQ_CFQQ_FNS(idle_window);
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CFQ_CFQQ_FNS(prio_changed);
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CFQ_CFQQ_FNS(slice_new);
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CFQ_CFQQ_FNS(sync);
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CFQ_CFQQ_FNS(coop);
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#undef CFQ_CFQQ_FNS
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#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
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blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
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#define cfq_log(cfqd, fmt, args...) \
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blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
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static void cfq_dispatch_insert(struct request_queue *, struct request *);
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static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
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struct io_context *, gfp_t);
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static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
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struct io_context *);
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static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
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int is_sync)
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{
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return cic->cfqq[!!is_sync];
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}
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static inline void cic_set_cfqq(struct cfq_io_context *cic,
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struct cfq_queue *cfqq, int is_sync)
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{
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cic->cfqq[!!is_sync] = cfqq;
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}
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/*
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* We regard a request as SYNC, if it's either a read or has the SYNC bit
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* set (in which case it could also be direct WRITE).
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*/
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static inline int cfq_bio_sync(struct bio *bio)
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{
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if (bio_data_dir(bio) == READ || bio_sync(bio))
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return 1;
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return 0;
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}
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/*
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* scheduler run of queue, if there are requests pending and no one in the
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* driver that will restart queueing
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*/
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static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
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{
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if (cfqd->busy_queues) {
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cfq_log(cfqd, "schedule dispatch");
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kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
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}
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}
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static int cfq_queue_empty(struct request_queue *q)
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{
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struct cfq_data *cfqd = q->elevator->elevator_data;
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return !cfqd->busy_queues;
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}
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/*
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* Scale schedule slice based on io priority. Use the sync time slice only
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* if a queue is marked sync and has sync io queued. A sync queue with async
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* io only, should not get full sync slice length.
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*/
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static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync,
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unsigned short prio)
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{
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const int base_slice = cfqd->cfq_slice[sync];
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WARN_ON(prio >= IOPRIO_BE_NR);
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return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
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}
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static inline int
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cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
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{
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return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
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}
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static inline void
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cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
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{
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cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
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cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
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}
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/*
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* We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
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* isn't valid until the first request from the dispatch is activated
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* and the slice time set.
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*/
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static inline int cfq_slice_used(struct cfq_queue *cfqq)
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{
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if (cfq_cfqq_slice_new(cfqq))
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return 0;
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if (time_before(jiffies, cfqq->slice_end))
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return 0;
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return 1;
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}
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/*
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* Lifted from AS - choose which of rq1 and rq2 that is best served now.
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* We choose the request that is closest to the head right now. Distance
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* behind the head is penalized and only allowed to a certain extent.
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*/
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static struct request *
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cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
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{
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sector_t last, s1, s2, d1 = 0, d2 = 0;
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unsigned long back_max;
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#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
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#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
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unsigned wrap = 0; /* bit mask: requests behind the disk head? */
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if (rq1 == NULL || rq1 == rq2)
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return rq2;
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if (rq2 == NULL)
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return rq1;
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if (rq_is_sync(rq1) && !rq_is_sync(rq2))
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return rq1;
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else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
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return rq2;
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if (rq_is_meta(rq1) && !rq_is_meta(rq2))
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return rq1;
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else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
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return rq2;
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s1 = rq1->sector;
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s2 = rq2->sector;
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last = cfqd->last_position;
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/*
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* by definition, 1KiB is 2 sectors
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*/
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back_max = cfqd->cfq_back_max * 2;
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/*
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* Strict one way elevator _except_ in the case where we allow
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* short backward seeks which are biased as twice the cost of a
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* similar forward seek.
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*/
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if (s1 >= last)
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d1 = s1 - last;
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else if (s1 + back_max >= last)
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d1 = (last - s1) * cfqd->cfq_back_penalty;
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else
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wrap |= CFQ_RQ1_WRAP;
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if (s2 >= last)
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d2 = s2 - last;
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else if (s2 + back_max >= last)
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d2 = (last - s2) * cfqd->cfq_back_penalty;
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else
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wrap |= CFQ_RQ2_WRAP;
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/* Found required data */
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/*
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* By doing switch() on the bit mask "wrap" we avoid having to
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* check two variables for all permutations: --> faster!
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*/
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switch (wrap) {
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case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
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if (d1 < d2)
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return rq1;
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else if (d2 < d1)
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return rq2;
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else {
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if (s1 >= s2)
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return rq1;
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else
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return rq2;
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}
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case CFQ_RQ2_WRAP:
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return rq1;
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case CFQ_RQ1_WRAP:
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return rq2;
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case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
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default:
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/*
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* Since both rqs are wrapped,
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* start with the one that's further behind head
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* (--> only *one* back seek required),
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* since back seek takes more time than forward.
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*/
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if (s1 <= s2)
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return rq1;
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else
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return rq2;
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}
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}
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/*
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* The below is leftmost cache rbtree addon
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*/
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static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
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{
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if (!root->left)
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root->left = rb_first(&root->rb);
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if (root->left)
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return rb_entry(root->left, struct cfq_queue, rb_node);
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return NULL;
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}
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static void rb_erase_init(struct rb_node *n, struct rb_root *root)
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{
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rb_erase(n, root);
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RB_CLEAR_NODE(n);
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}
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static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
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{
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if (root->left == n)
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root->left = NULL;
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rb_erase_init(n, &root->rb);
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}
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/*
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* would be nice to take fifo expire time into account as well
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*/
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static struct request *
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cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
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struct request *last)
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{
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struct rb_node *rbnext = rb_next(&last->rb_node);
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struct rb_node *rbprev = rb_prev(&last->rb_node);
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struct request *next = NULL, *prev = NULL;
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BUG_ON(RB_EMPTY_NODE(&last->rb_node));
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if (rbprev)
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prev = rb_entry_rq(rbprev);
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if (rbnext)
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next = rb_entry_rq(rbnext);
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else {
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rbnext = rb_first(&cfqq->sort_list);
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if (rbnext && rbnext != &last->rb_node)
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next = rb_entry_rq(rbnext);
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}
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return cfq_choose_req(cfqd, next, prev);
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}
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static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
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struct cfq_queue *cfqq)
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{
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/*
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* just an approximation, should be ok.
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*/
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return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) -
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cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
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}
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/*
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* The cfqd->service_tree holds all pending cfq_queue's that have
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* requests waiting to be processed. It is sorted in the order that
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* we will service the queues.
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*/
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static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
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int add_front)
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{
|
|
struct rb_node **p, *parent;
|
|
struct cfq_queue *__cfqq;
|
|
unsigned long rb_key;
|
|
int left;
|
|
|
|
if (cfq_class_idle(cfqq)) {
|
|
rb_key = CFQ_IDLE_DELAY;
|
|
parent = rb_last(&cfqd->service_tree.rb);
|
|
if (parent && parent != &cfqq->rb_node) {
|
|
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
|
|
rb_key += __cfqq->rb_key;
|
|
} else
|
|
rb_key += jiffies;
|
|
} else if (!add_front) {
|
|
rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
|
|
rb_key += cfqq->slice_resid;
|
|
cfqq->slice_resid = 0;
|
|
} else
|
|
rb_key = 0;
|
|
|
|
if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
|
|
/*
|
|
* same position, nothing more to do
|
|
*/
|
|
if (rb_key == cfqq->rb_key)
|
|
return;
|
|
|
|
cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
|
|
}
|
|
|
|
left = 1;
|
|
parent = NULL;
|
|
p = &cfqd->service_tree.rb.rb_node;
|
|
while (*p) {
|
|
struct rb_node **n;
|
|
|
|
parent = *p;
|
|
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
|
|
|
|
/*
|
|
* sort RT queues first, we always want to give
|
|
* preference to them. IDLE queues goes to the back.
|
|
* after that, sort on the next service time.
|
|
*/
|
|
if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
|
|
n = &(*p)->rb_left;
|
|
else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
|
|
n = &(*p)->rb_right;
|
|
else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
|
|
n = &(*p)->rb_left;
|
|
else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
|
|
n = &(*p)->rb_right;
|
|
else if (rb_key < __cfqq->rb_key)
|
|
n = &(*p)->rb_left;
|
|
else
|
|
n = &(*p)->rb_right;
|
|
|
|
if (n == &(*p)->rb_right)
|
|
left = 0;
|
|
|
|
p = n;
|
|
}
|
|
|
|
if (left)
|
|
cfqd->service_tree.left = &cfqq->rb_node;
|
|
|
|
cfqq->rb_key = rb_key;
|
|
rb_link_node(&cfqq->rb_node, parent, p);
|
|
rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
|
|
sector_t sector, struct rb_node **ret_parent,
|
|
struct rb_node ***rb_link)
|
|
{
|
|
struct rb_node **p, *parent;
|
|
struct cfq_queue *cfqq = NULL;
|
|
|
|
parent = NULL;
|
|
p = &root->rb_node;
|
|
while (*p) {
|
|
struct rb_node **n;
|
|
|
|
parent = *p;
|
|
cfqq = rb_entry(parent, struct cfq_queue, p_node);
|
|
|
|
/*
|
|
* Sort strictly based on sector. Smallest to the left,
|
|
* largest to the right.
|
|
*/
|
|
if (sector > cfqq->next_rq->sector)
|
|
n = &(*p)->rb_right;
|
|
else if (sector < cfqq->next_rq->sector)
|
|
n = &(*p)->rb_left;
|
|
else
|
|
break;
|
|
p = n;
|
|
cfqq = NULL;
|
|
}
|
|
|
|
*ret_parent = parent;
|
|
if (rb_link)
|
|
*rb_link = p;
|
|
return cfqq;
|
|
}
|
|
|
|
static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
struct rb_node **p, *parent;
|
|
struct cfq_queue *__cfqq;
|
|
|
|
if (cfqq->p_root) {
|
|
rb_erase(&cfqq->p_node, cfqq->p_root);
|
|
cfqq->p_root = NULL;
|
|
}
|
|
|
|
if (cfq_class_idle(cfqq))
|
|
return;
|
|
if (!cfqq->next_rq)
|
|
return;
|
|
|
|
cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
|
|
__cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, cfqq->next_rq->sector,
|
|
&parent, &p);
|
|
if (!__cfqq) {
|
|
rb_link_node(&cfqq->p_node, parent, p);
|
|
rb_insert_color(&cfqq->p_node, cfqq->p_root);
|
|
} else
|
|
cfqq->p_root = NULL;
|
|
}
|
|
|
|
/*
|
|
* Update cfqq's position in the service tree.
|
|
*/
|
|
static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
/*
|
|
* Resorting requires the cfqq to be on the RR list already.
|
|
*/
|
|
if (cfq_cfqq_on_rr(cfqq)) {
|
|
cfq_service_tree_add(cfqd, cfqq, 0);
|
|
cfq_prio_tree_add(cfqd, cfqq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* add to busy list of queues for service, trying to be fair in ordering
|
|
* the pending list according to last request service
|
|
*/
|
|
static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
|
|
BUG_ON(cfq_cfqq_on_rr(cfqq));
|
|
cfq_mark_cfqq_on_rr(cfqq);
|
|
cfqd->busy_queues++;
|
|
if (cfq_class_rt(cfqq))
|
|
cfqd->busy_rt_queues++;
|
|
|
|
cfq_resort_rr_list(cfqd, cfqq);
|
|
}
|
|
|
|
/*
|
|
* Called when the cfqq no longer has requests pending, remove it from
|
|
* the service tree.
|
|
*/
|
|
static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
|
|
BUG_ON(!cfq_cfqq_on_rr(cfqq));
|
|
cfq_clear_cfqq_on_rr(cfqq);
|
|
|
|
if (!RB_EMPTY_NODE(&cfqq->rb_node))
|
|
cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
|
|
if (cfqq->p_root) {
|
|
rb_erase(&cfqq->p_node, cfqq->p_root);
|
|
cfqq->p_root = NULL;
|
|
}
|
|
|
|
BUG_ON(!cfqd->busy_queues);
|
|
cfqd->busy_queues--;
|
|
if (cfq_class_rt(cfqq))
|
|
cfqd->busy_rt_queues--;
|
|
}
|
|
|
|
/*
|
|
* rb tree support functions
|
|
*/
|
|
static void cfq_del_rq_rb(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
const int sync = rq_is_sync(rq);
|
|
|
|
BUG_ON(!cfqq->queued[sync]);
|
|
cfqq->queued[sync]--;
|
|
|
|
elv_rb_del(&cfqq->sort_list, rq);
|
|
|
|
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
cfq_del_cfqq_rr(cfqd, cfqq);
|
|
}
|
|
|
|
static void cfq_add_rq_rb(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
struct request *__alias, *prev;
|
|
|
|
cfqq->queued[rq_is_sync(rq)]++;
|
|
|
|
/*
|
|
* looks a little odd, but the first insert might return an alias.
|
|
* if that happens, put the alias on the dispatch list
|
|
*/
|
|
while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
|
|
cfq_dispatch_insert(cfqd->queue, __alias);
|
|
|
|
if (!cfq_cfqq_on_rr(cfqq))
|
|
cfq_add_cfqq_rr(cfqd, cfqq);
|
|
|
|
/*
|
|
* check if this request is a better next-serve candidate
|
|
*/
|
|
prev = cfqq->next_rq;
|
|
cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
|
|
|
|
/*
|
|
* adjust priority tree position, if ->next_rq changes
|
|
*/
|
|
if (prev != cfqq->next_rq)
|
|
cfq_prio_tree_add(cfqd, cfqq);
|
|
|
|
BUG_ON(!cfqq->next_rq);
|
|
}
|
|
|
|
static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
|
|
{
|
|
elv_rb_del(&cfqq->sort_list, rq);
|
|
cfqq->queued[rq_is_sync(rq)]--;
|
|
cfq_add_rq_rb(rq);
|
|
}
|
|
|
|
static struct request *
|
|
cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
struct cfq_io_context *cic;
|
|
struct cfq_queue *cfqq;
|
|
|
|
cic = cfq_cic_lookup(cfqd, tsk->io_context);
|
|
if (!cic)
|
|
return NULL;
|
|
|
|
cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
|
|
if (cfqq) {
|
|
sector_t sector = bio->bi_sector + bio_sectors(bio);
|
|
|
|
return elv_rb_find(&cfqq->sort_list, sector);
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void cfq_activate_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
|
|
cfqd->rq_in_driver++;
|
|
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
|
|
cfqd->rq_in_driver);
|
|
|
|
cfqd->last_position = rq->hard_sector + rq->hard_nr_sectors;
|
|
}
|
|
|
|
static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
|
|
WARN_ON(!cfqd->rq_in_driver);
|
|
cfqd->rq_in_driver--;
|
|
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
|
|
cfqd->rq_in_driver);
|
|
}
|
|
|
|
static void cfq_remove_request(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
if (cfqq->next_rq == rq)
|
|
cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
|
|
|
|
list_del_init(&rq->queuelist);
|
|
cfq_del_rq_rb(rq);
|
|
|
|
cfqq->cfqd->rq_queued--;
|
|
if (rq_is_meta(rq)) {
|
|
WARN_ON(!cfqq->meta_pending);
|
|
cfqq->meta_pending--;
|
|
}
|
|
}
|
|
|
|
static int cfq_merge(struct request_queue *q, struct request **req,
|
|
struct bio *bio)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct request *__rq;
|
|
|
|
__rq = cfq_find_rq_fmerge(cfqd, bio);
|
|
if (__rq && elv_rq_merge_ok(__rq, bio)) {
|
|
*req = __rq;
|
|
return ELEVATOR_FRONT_MERGE;
|
|
}
|
|
|
|
return ELEVATOR_NO_MERGE;
|
|
}
|
|
|
|
static void cfq_merged_request(struct request_queue *q, struct request *req,
|
|
int type)
|
|
{
|
|
if (type == ELEVATOR_FRONT_MERGE) {
|
|
struct cfq_queue *cfqq = RQ_CFQQ(req);
|
|
|
|
cfq_reposition_rq_rb(cfqq, req);
|
|
}
|
|
}
|
|
|
|
static void
|
|
cfq_merged_requests(struct request_queue *q, struct request *rq,
|
|
struct request *next)
|
|
{
|
|
/*
|
|
* reposition in fifo if next is older than rq
|
|
*/
|
|
if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
|
|
time_before(next->start_time, rq->start_time))
|
|
list_move(&rq->queuelist, &next->queuelist);
|
|
|
|
cfq_remove_request(next);
|
|
}
|
|
|
|
static int cfq_allow_merge(struct request_queue *q, struct request *rq,
|
|
struct bio *bio)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_io_context *cic;
|
|
struct cfq_queue *cfqq;
|
|
|
|
/*
|
|
* Disallow merge of a sync bio into an async request.
|
|
*/
|
|
if (cfq_bio_sync(bio) && !rq_is_sync(rq))
|
|
return 0;
|
|
|
|
/*
|
|
* Lookup the cfqq that this bio will be queued with. Allow
|
|
* merge only if rq is queued there.
|
|
*/
|
|
cic = cfq_cic_lookup(cfqd, current->io_context);
|
|
if (!cic)
|
|
return 0;
|
|
|
|
cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
|
|
if (cfqq == RQ_CFQQ(rq))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __cfq_set_active_queue(struct cfq_data *cfqd,
|
|
struct cfq_queue *cfqq)
|
|
{
|
|
if (cfqq) {
|
|
cfq_log_cfqq(cfqd, cfqq, "set_active");
|
|
cfqq->slice_end = 0;
|
|
cfqq->slice_dispatch = 0;
|
|
|
|
cfq_clear_cfqq_wait_request(cfqq);
|
|
cfq_clear_cfqq_must_dispatch(cfqq);
|
|
cfq_clear_cfqq_must_alloc_slice(cfqq);
|
|
cfq_clear_cfqq_fifo_expire(cfqq);
|
|
cfq_mark_cfqq_slice_new(cfqq);
|
|
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
}
|
|
|
|
cfqd->active_queue = cfqq;
|
|
}
|
|
|
|
/*
|
|
* current cfqq expired its slice (or was too idle), select new one
|
|
*/
|
|
static void
|
|
__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
int timed_out)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
|
|
|
|
if (cfq_cfqq_wait_request(cfqq))
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
|
|
cfq_clear_cfqq_wait_request(cfqq);
|
|
|
|
/*
|
|
* store what was left of this slice, if the queue idled/timed out
|
|
*/
|
|
if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
|
|
cfqq->slice_resid = cfqq->slice_end - jiffies;
|
|
cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
|
|
}
|
|
|
|
cfq_resort_rr_list(cfqd, cfqq);
|
|
|
|
if (cfqq == cfqd->active_queue)
|
|
cfqd->active_queue = NULL;
|
|
|
|
if (cfqd->active_cic) {
|
|
put_io_context(cfqd->active_cic->ioc);
|
|
cfqd->active_cic = NULL;
|
|
}
|
|
}
|
|
|
|
static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out)
|
|
{
|
|
struct cfq_queue *cfqq = cfqd->active_queue;
|
|
|
|
if (cfqq)
|
|
__cfq_slice_expired(cfqd, cfqq, timed_out);
|
|
}
|
|
|
|
/*
|
|
* Get next queue for service. Unless we have a queue preemption,
|
|
* we'll simply select the first cfqq in the service tree.
|
|
*/
|
|
static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
|
|
{
|
|
if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
|
|
return NULL;
|
|
|
|
return cfq_rb_first(&cfqd->service_tree);
|
|
}
|
|
|
|
/*
|
|
* Get and set a new active queue for service.
|
|
*/
|
|
static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
|
|
struct cfq_queue *cfqq)
|
|
{
|
|
if (!cfqq) {
|
|
cfqq = cfq_get_next_queue(cfqd);
|
|
if (cfqq)
|
|
cfq_clear_cfqq_coop(cfqq);
|
|
}
|
|
|
|
__cfq_set_active_queue(cfqd, cfqq);
|
|
return cfqq;
|
|
}
|
|
|
|
static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
|
|
struct request *rq)
|
|
{
|
|
if (rq->sector >= cfqd->last_position)
|
|
return rq->sector - cfqd->last_position;
|
|
else
|
|
return cfqd->last_position - rq->sector;
|
|
}
|
|
|
|
#define CIC_SEEK_THR 8 * 1024
|
|
#define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
|
|
|
|
static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
|
|
{
|
|
struct cfq_io_context *cic = cfqd->active_cic;
|
|
sector_t sdist = cic->seek_mean;
|
|
|
|
if (!sample_valid(cic->seek_samples))
|
|
sdist = CIC_SEEK_THR;
|
|
|
|
return cfq_dist_from_last(cfqd, rq) <= sdist;
|
|
}
|
|
|
|
static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
|
|
struct cfq_queue *cur_cfqq)
|
|
{
|
|
struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
|
|
struct rb_node *parent, *node;
|
|
struct cfq_queue *__cfqq;
|
|
sector_t sector = cfqd->last_position;
|
|
|
|
if (RB_EMPTY_ROOT(root))
|
|
return NULL;
|
|
|
|
/*
|
|
* First, if we find a request starting at the end of the last
|
|
* request, choose it.
|
|
*/
|
|
__cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
|
|
if (__cfqq)
|
|
return __cfqq;
|
|
|
|
/*
|
|
* If the exact sector wasn't found, the parent of the NULL leaf
|
|
* will contain the closest sector.
|
|
*/
|
|
__cfqq = rb_entry(parent, struct cfq_queue, p_node);
|
|
if (cfq_rq_close(cfqd, __cfqq->next_rq))
|
|
return __cfqq;
|
|
|
|
if (__cfqq->next_rq->sector < sector)
|
|
node = rb_next(&__cfqq->p_node);
|
|
else
|
|
node = rb_prev(&__cfqq->p_node);
|
|
if (!node)
|
|
return NULL;
|
|
|
|
__cfqq = rb_entry(node, struct cfq_queue, p_node);
|
|
if (cfq_rq_close(cfqd, __cfqq->next_rq))
|
|
return __cfqq;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* cfqd - obvious
|
|
* cur_cfqq - passed in so that we don't decide that the current queue is
|
|
* closely cooperating with itself.
|
|
*
|
|
* So, basically we're assuming that that cur_cfqq has dispatched at least
|
|
* one request, and that cfqd->last_position reflects a position on the disk
|
|
* associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
|
|
* assumption.
|
|
*/
|
|
static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
|
|
struct cfq_queue *cur_cfqq,
|
|
int probe)
|
|
{
|
|
struct cfq_queue *cfqq;
|
|
|
|
/*
|
|
* A valid cfq_io_context is necessary to compare requests against
|
|
* the seek_mean of the current cfqq.
|
|
*/
|
|
if (!cfqd->active_cic)
|
|
return NULL;
|
|
|
|
/*
|
|
* We should notice if some of the queues are cooperating, eg
|
|
* working closely on the same area of the disk. In that case,
|
|
* we can group them together and don't waste time idling.
|
|
*/
|
|
cfqq = cfqq_close(cfqd, cur_cfqq);
|
|
if (!cfqq)
|
|
return NULL;
|
|
|
|
if (cfq_cfqq_coop(cfqq))
|
|
return NULL;
|
|
|
|
if (!probe)
|
|
cfq_mark_cfqq_coop(cfqq);
|
|
return cfqq;
|
|
}
|
|
|
|
static void cfq_arm_slice_timer(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq = cfqd->active_queue;
|
|
struct cfq_io_context *cic;
|
|
unsigned long sl;
|
|
|
|
/*
|
|
* SSD device without seek penalty, disable idling. But only do so
|
|
* for devices that support queuing, otherwise we still have a problem
|
|
* with sync vs async workloads.
|
|
*/
|
|
if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
|
|
return;
|
|
|
|
WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
|
|
WARN_ON(cfq_cfqq_slice_new(cfqq));
|
|
|
|
/*
|
|
* idle is disabled, either manually or by past process history
|
|
*/
|
|
if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
|
|
return;
|
|
|
|
/*
|
|
* still requests with the driver, don't idle
|
|
*/
|
|
if (cfqd->rq_in_driver)
|
|
return;
|
|
|
|
/*
|
|
* task has exited, don't wait
|
|
*/
|
|
cic = cfqd->active_cic;
|
|
if (!cic || !atomic_read(&cic->ioc->nr_tasks))
|
|
return;
|
|
|
|
cfq_mark_cfqq_wait_request(cfqq);
|
|
|
|
/*
|
|
* we don't want to idle for seeks, but we do want to allow
|
|
* fair distribution of slice time for a process doing back-to-back
|
|
* seeks. so allow a little bit of time for him to submit a new rq
|
|
*/
|
|
sl = cfqd->cfq_slice_idle;
|
|
if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
|
|
sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
|
|
|
|
mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
|
|
cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
|
|
}
|
|
|
|
/*
|
|
* Move request from internal lists to the request queue dispatch list.
|
|
*/
|
|
static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
|
|
|
|
cfq_remove_request(rq);
|
|
cfqq->dispatched++;
|
|
elv_dispatch_sort(q, rq);
|
|
|
|
if (cfq_cfqq_sync(cfqq))
|
|
cfqd->sync_flight++;
|
|
}
|
|
|
|
/*
|
|
* return expired entry, or NULL to just start from scratch in rbtree
|
|
*/
|
|
static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
|
|
{
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
struct request *rq;
|
|
int fifo;
|
|
|
|
if (cfq_cfqq_fifo_expire(cfqq))
|
|
return NULL;
|
|
|
|
cfq_mark_cfqq_fifo_expire(cfqq);
|
|
|
|
if (list_empty(&cfqq->fifo))
|
|
return NULL;
|
|
|
|
fifo = cfq_cfqq_sync(cfqq);
|
|
rq = rq_entry_fifo(cfqq->fifo.next);
|
|
|
|
if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo]))
|
|
rq = NULL;
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "fifo=%p", rq);
|
|
return rq;
|
|
}
|
|
|
|
static inline int
|
|
cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
const int base_rq = cfqd->cfq_slice_async_rq;
|
|
|
|
WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
|
|
|
|
return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
|
|
}
|
|
|
|
/*
|
|
* Select a queue for service. If we have a current active queue,
|
|
* check whether to continue servicing it, or retrieve and set a new one.
|
|
*/
|
|
static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq, *new_cfqq = NULL;
|
|
|
|
cfqq = cfqd->active_queue;
|
|
if (!cfqq)
|
|
goto new_queue;
|
|
|
|
/*
|
|
* The active queue has run out of time, expire it and select new.
|
|
*/
|
|
if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
|
|
goto expire;
|
|
|
|
/*
|
|
* If we have a RT cfqq waiting, then we pre-empt the current non-rt
|
|
* cfqq.
|
|
*/
|
|
if (!cfq_class_rt(cfqq) && cfqd->busy_rt_queues) {
|
|
/*
|
|
* We simulate this as cfqq timed out so that it gets to bank
|
|
* the remaining of its time slice.
|
|
*/
|
|
cfq_log_cfqq(cfqd, cfqq, "preempt");
|
|
cfq_slice_expired(cfqd, 1);
|
|
goto new_queue;
|
|
}
|
|
|
|
/*
|
|
* The active queue has requests and isn't expired, allow it to
|
|
* dispatch.
|
|
*/
|
|
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
goto keep_queue;
|
|
|
|
/*
|
|
* If another queue has a request waiting within our mean seek
|
|
* distance, let it run. The expire code will check for close
|
|
* cooperators and put the close queue at the front of the service
|
|
* tree.
|
|
*/
|
|
new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
|
|
if (new_cfqq)
|
|
goto expire;
|
|
|
|
/*
|
|
* No requests pending. If the active queue still has requests in
|
|
* flight or is idling for a new request, allow either of these
|
|
* conditions to happen (or time out) before selecting a new queue.
|
|
*/
|
|
if (timer_pending(&cfqd->idle_slice_timer) ||
|
|
(cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
|
|
cfqq = NULL;
|
|
goto keep_queue;
|
|
}
|
|
|
|
expire:
|
|
cfq_slice_expired(cfqd, 0);
|
|
new_queue:
|
|
cfqq = cfq_set_active_queue(cfqd, new_cfqq);
|
|
keep_queue:
|
|
return cfqq;
|
|
}
|
|
|
|
static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
|
|
{
|
|
int dispatched = 0;
|
|
|
|
while (cfqq->next_rq) {
|
|
cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
|
|
dispatched++;
|
|
}
|
|
|
|
BUG_ON(!list_empty(&cfqq->fifo));
|
|
return dispatched;
|
|
}
|
|
|
|
/*
|
|
* Drain our current requests. Used for barriers and when switching
|
|
* io schedulers on-the-fly.
|
|
*/
|
|
static int cfq_forced_dispatch(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq;
|
|
int dispatched = 0;
|
|
|
|
while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
|
|
dispatched += __cfq_forced_dispatch_cfqq(cfqq);
|
|
|
|
cfq_slice_expired(cfqd, 0);
|
|
|
|
BUG_ON(cfqd->busy_queues);
|
|
|
|
cfq_log(cfqd, "forced_dispatch=%d\n", dispatched);
|
|
return dispatched;
|
|
}
|
|
|
|
/*
|
|
* Dispatch a request from cfqq, moving them to the request queue
|
|
* dispatch list.
|
|
*/
|
|
static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
struct request *rq;
|
|
|
|
BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
|
|
|
|
/*
|
|
* follow expired path, else get first next available
|
|
*/
|
|
rq = cfq_check_fifo(cfqq);
|
|
if (!rq)
|
|
rq = cfqq->next_rq;
|
|
|
|
/*
|
|
* insert request into driver dispatch list
|
|
*/
|
|
cfq_dispatch_insert(cfqd->queue, rq);
|
|
|
|
if (!cfqd->active_cic) {
|
|
struct cfq_io_context *cic = RQ_CIC(rq);
|
|
|
|
atomic_inc(&cic->ioc->refcount);
|
|
cfqd->active_cic = cic;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Find the cfqq that we need to service and move a request from that to the
|
|
* dispatch list
|
|
*/
|
|
static int cfq_dispatch_requests(struct request_queue *q, int force)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq;
|
|
unsigned int max_dispatch;
|
|
|
|
if (!cfqd->busy_queues)
|
|
return 0;
|
|
|
|
if (unlikely(force))
|
|
return cfq_forced_dispatch(cfqd);
|
|
|
|
cfqq = cfq_select_queue(cfqd);
|
|
if (!cfqq)
|
|
return 0;
|
|
|
|
/*
|
|
* If this is an async queue and we have sync IO in flight, let it wait
|
|
*/
|
|
if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
|
|
return 0;
|
|
|
|
max_dispatch = cfqd->cfq_quantum;
|
|
if (cfq_class_idle(cfqq))
|
|
max_dispatch = 1;
|
|
|
|
/*
|
|
* Does this cfqq already have too much IO in flight?
|
|
*/
|
|
if (cfqq->dispatched >= max_dispatch) {
|
|
/*
|
|
* idle queue must always only have a single IO in flight
|
|
*/
|
|
if (cfq_class_idle(cfqq))
|
|
return 0;
|
|
|
|
/*
|
|
* We have other queues, don't allow more IO from this one
|
|
*/
|
|
if (cfqd->busy_queues > 1)
|
|
return 0;
|
|
|
|
/*
|
|
* we are the only queue, allow up to 4 times of 'quantum'
|
|
*/
|
|
if (cfqq->dispatched >= 4 * max_dispatch)
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Dispatch a request from this cfqq
|
|
*/
|
|
cfq_dispatch_request(cfqd, cfqq);
|
|
cfqq->slice_dispatch++;
|
|
cfq_clear_cfqq_must_dispatch(cfqq);
|
|
|
|
/*
|
|
* expire an async queue immediately if it has used up its slice. idle
|
|
* queue always expire after 1 dispatch round.
|
|
*/
|
|
if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
|
|
cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
|
|
cfq_class_idle(cfqq))) {
|
|
cfqq->slice_end = jiffies + 1;
|
|
cfq_slice_expired(cfqd, 0);
|
|
}
|
|
|
|
cfq_log(cfqd, "dispatched a request");
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* task holds one reference to the queue, dropped when task exits. each rq
|
|
* in-flight on this queue also holds a reference, dropped when rq is freed.
|
|
*
|
|
* queue lock must be held here.
|
|
*/
|
|
static void cfq_put_queue(struct cfq_queue *cfqq)
|
|
{
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
|
|
BUG_ON(atomic_read(&cfqq->ref) <= 0);
|
|
|
|
if (!atomic_dec_and_test(&cfqq->ref))
|
|
return;
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "put_queue");
|
|
BUG_ON(rb_first(&cfqq->sort_list));
|
|
BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
|
|
BUG_ON(cfq_cfqq_on_rr(cfqq));
|
|
|
|
if (unlikely(cfqd->active_queue == cfqq)) {
|
|
__cfq_slice_expired(cfqd, cfqq, 0);
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
|
|
kmem_cache_free(cfq_pool, cfqq);
|
|
}
|
|
|
|
/*
|
|
* Must always be called with the rcu_read_lock() held
|
|
*/
|
|
static void
|
|
__call_for_each_cic(struct io_context *ioc,
|
|
void (*func)(struct io_context *, struct cfq_io_context *))
|
|
{
|
|
struct cfq_io_context *cic;
|
|
struct hlist_node *n;
|
|
|
|
hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
|
|
func(ioc, cic);
|
|
}
|
|
|
|
/*
|
|
* Call func for each cic attached to this ioc.
|
|
*/
|
|
static void
|
|
call_for_each_cic(struct io_context *ioc,
|
|
void (*func)(struct io_context *, struct cfq_io_context *))
|
|
{
|
|
rcu_read_lock();
|
|
__call_for_each_cic(ioc, func);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static void cfq_cic_free_rcu(struct rcu_head *head)
|
|
{
|
|
struct cfq_io_context *cic;
|
|
|
|
cic = container_of(head, struct cfq_io_context, rcu_head);
|
|
|
|
kmem_cache_free(cfq_ioc_pool, cic);
|
|
elv_ioc_count_dec(ioc_count);
|
|
|
|
if (ioc_gone) {
|
|
/*
|
|
* CFQ scheduler is exiting, grab exit lock and check
|
|
* the pending io context count. If it hits zero,
|
|
* complete ioc_gone and set it back to NULL
|
|
*/
|
|
spin_lock(&ioc_gone_lock);
|
|
if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
|
|
complete(ioc_gone);
|
|
ioc_gone = NULL;
|
|
}
|
|
spin_unlock(&ioc_gone_lock);
|
|
}
|
|
}
|
|
|
|
static void cfq_cic_free(struct cfq_io_context *cic)
|
|
{
|
|
call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
|
|
}
|
|
|
|
static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
|
|
{
|
|
unsigned long flags;
|
|
|
|
BUG_ON(!cic->dead_key);
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
radix_tree_delete(&ioc->radix_root, cic->dead_key);
|
|
hlist_del_rcu(&cic->cic_list);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
cfq_cic_free(cic);
|
|
}
|
|
|
|
/*
|
|
* Must be called with rcu_read_lock() held or preemption otherwise disabled.
|
|
* Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
|
|
* and ->trim() which is called with the task lock held
|
|
*/
|
|
static void cfq_free_io_context(struct io_context *ioc)
|
|
{
|
|
/*
|
|
* ioc->refcount is zero here, or we are called from elv_unregister(),
|
|
* so no more cic's are allowed to be linked into this ioc. So it
|
|
* should be ok to iterate over the known list, we will see all cic's
|
|
* since no new ones are added.
|
|
*/
|
|
__call_for_each_cic(ioc, cic_free_func);
|
|
}
|
|
|
|
static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
if (unlikely(cfqq == cfqd->active_queue)) {
|
|
__cfq_slice_expired(cfqd, cfqq, 0);
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
|
|
cfq_put_queue(cfqq);
|
|
}
|
|
|
|
static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
struct io_context *ioc = cic->ioc;
|
|
|
|
list_del_init(&cic->queue_list);
|
|
|
|
/*
|
|
* Make sure key == NULL is seen for dead queues
|
|
*/
|
|
smp_wmb();
|
|
cic->dead_key = (unsigned long) cic->key;
|
|
cic->key = NULL;
|
|
|
|
if (ioc->ioc_data == cic)
|
|
rcu_assign_pointer(ioc->ioc_data, NULL);
|
|
|
|
if (cic->cfqq[BLK_RW_ASYNC]) {
|
|
cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
|
|
cic->cfqq[BLK_RW_ASYNC] = NULL;
|
|
}
|
|
|
|
if (cic->cfqq[BLK_RW_SYNC]) {
|
|
cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
|
|
cic->cfqq[BLK_RW_SYNC] = NULL;
|
|
}
|
|
}
|
|
|
|
static void cfq_exit_single_io_context(struct io_context *ioc,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
struct cfq_data *cfqd = cic->key;
|
|
|
|
if (cfqd) {
|
|
struct request_queue *q = cfqd->queue;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
/*
|
|
* Ensure we get a fresh copy of the ->key to prevent
|
|
* race between exiting task and queue
|
|
*/
|
|
smp_read_barrier_depends();
|
|
if (cic->key)
|
|
__cfq_exit_single_io_context(cfqd, cic);
|
|
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The process that ioc belongs to has exited, we need to clean up
|
|
* and put the internal structures we have that belongs to that process.
|
|
*/
|
|
static void cfq_exit_io_context(struct io_context *ioc)
|
|
{
|
|
call_for_each_cic(ioc, cfq_exit_single_io_context);
|
|
}
|
|
|
|
static struct cfq_io_context *
|
|
cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
|
|
{
|
|
struct cfq_io_context *cic;
|
|
|
|
cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
|
|
cfqd->queue->node);
|
|
if (cic) {
|
|
cic->last_end_request = jiffies;
|
|
INIT_LIST_HEAD(&cic->queue_list);
|
|
INIT_HLIST_NODE(&cic->cic_list);
|
|
cic->dtor = cfq_free_io_context;
|
|
cic->exit = cfq_exit_io_context;
|
|
elv_ioc_count_inc(ioc_count);
|
|
}
|
|
|
|
return cic;
|
|
}
|
|
|
|
static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
int ioprio_class;
|
|
|
|
if (!cfq_cfqq_prio_changed(cfqq))
|
|
return;
|
|
|
|
ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
|
|
switch (ioprio_class) {
|
|
default:
|
|
printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
|
|
case IOPRIO_CLASS_NONE:
|
|
/*
|
|
* no prio set, inherit CPU scheduling settings
|
|
*/
|
|
cfqq->ioprio = task_nice_ioprio(tsk);
|
|
cfqq->ioprio_class = task_nice_ioclass(tsk);
|
|
break;
|
|
case IOPRIO_CLASS_RT:
|
|
cfqq->ioprio = task_ioprio(ioc);
|
|
cfqq->ioprio_class = IOPRIO_CLASS_RT;
|
|
break;
|
|
case IOPRIO_CLASS_BE:
|
|
cfqq->ioprio = task_ioprio(ioc);
|
|
cfqq->ioprio_class = IOPRIO_CLASS_BE;
|
|
break;
|
|
case IOPRIO_CLASS_IDLE:
|
|
cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
|
|
cfqq->ioprio = 7;
|
|
cfq_clear_cfqq_idle_window(cfqq);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* keep track of original prio settings in case we have to temporarily
|
|
* elevate the priority of this queue
|
|
*/
|
|
cfqq->org_ioprio = cfqq->ioprio;
|
|
cfqq->org_ioprio_class = cfqq->ioprio_class;
|
|
cfq_clear_cfqq_prio_changed(cfqq);
|
|
}
|
|
|
|
static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
|
|
{
|
|
struct cfq_data *cfqd = cic->key;
|
|
struct cfq_queue *cfqq;
|
|
unsigned long flags;
|
|
|
|
if (unlikely(!cfqd))
|
|
return;
|
|
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
|
|
cfqq = cic->cfqq[BLK_RW_ASYNC];
|
|
if (cfqq) {
|
|
struct cfq_queue *new_cfqq;
|
|
new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
|
|
GFP_ATOMIC);
|
|
if (new_cfqq) {
|
|
cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
|
|
cfq_put_queue(cfqq);
|
|
}
|
|
}
|
|
|
|
cfqq = cic->cfqq[BLK_RW_SYNC];
|
|
if (cfqq)
|
|
cfq_mark_cfqq_prio_changed(cfqq);
|
|
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
|
|
static void cfq_ioc_set_ioprio(struct io_context *ioc)
|
|
{
|
|
call_for_each_cic(ioc, changed_ioprio);
|
|
ioc->ioprio_changed = 0;
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
|
|
struct io_context *ioc, gfp_t gfp_mask)
|
|
{
|
|
struct cfq_queue *cfqq, *new_cfqq = NULL;
|
|
struct cfq_io_context *cic;
|
|
|
|
retry:
|
|
cic = cfq_cic_lookup(cfqd, ioc);
|
|
/* cic always exists here */
|
|
cfqq = cic_to_cfqq(cic, is_sync);
|
|
|
|
if (!cfqq) {
|
|
if (new_cfqq) {
|
|
cfqq = new_cfqq;
|
|
new_cfqq = NULL;
|
|
} else if (gfp_mask & __GFP_WAIT) {
|
|
/*
|
|
* Inform the allocator of the fact that we will
|
|
* just repeat this allocation if it fails, to allow
|
|
* the allocator to do whatever it needs to attempt to
|
|
* free memory.
|
|
*/
|
|
spin_unlock_irq(cfqd->queue->queue_lock);
|
|
new_cfqq = kmem_cache_alloc_node(cfq_pool,
|
|
gfp_mask | __GFP_NOFAIL | __GFP_ZERO,
|
|
cfqd->queue->node);
|
|
spin_lock_irq(cfqd->queue->queue_lock);
|
|
goto retry;
|
|
} else {
|
|
cfqq = kmem_cache_alloc_node(cfq_pool,
|
|
gfp_mask | __GFP_ZERO,
|
|
cfqd->queue->node);
|
|
if (!cfqq)
|
|
goto out;
|
|
}
|
|
|
|
RB_CLEAR_NODE(&cfqq->rb_node);
|
|
RB_CLEAR_NODE(&cfqq->p_node);
|
|
INIT_LIST_HEAD(&cfqq->fifo);
|
|
|
|
atomic_set(&cfqq->ref, 0);
|
|
cfqq->cfqd = cfqd;
|
|
|
|
cfq_mark_cfqq_prio_changed(cfqq);
|
|
|
|
cfq_init_prio_data(cfqq, ioc);
|
|
|
|
if (is_sync) {
|
|
if (!cfq_class_idle(cfqq))
|
|
cfq_mark_cfqq_idle_window(cfqq);
|
|
cfq_mark_cfqq_sync(cfqq);
|
|
}
|
|
cfqq->pid = current->pid;
|
|
cfq_log_cfqq(cfqd, cfqq, "alloced");
|
|
}
|
|
|
|
if (new_cfqq)
|
|
kmem_cache_free(cfq_pool, new_cfqq);
|
|
|
|
out:
|
|
WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
|
|
return cfqq;
|
|
}
|
|
|
|
static struct cfq_queue **
|
|
cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
|
|
{
|
|
switch (ioprio_class) {
|
|
case IOPRIO_CLASS_RT:
|
|
return &cfqd->async_cfqq[0][ioprio];
|
|
case IOPRIO_CLASS_BE:
|
|
return &cfqd->async_cfqq[1][ioprio];
|
|
case IOPRIO_CLASS_IDLE:
|
|
return &cfqd->async_idle_cfqq;
|
|
default:
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
|
|
gfp_t gfp_mask)
|
|
{
|
|
const int ioprio = task_ioprio(ioc);
|
|
const int ioprio_class = task_ioprio_class(ioc);
|
|
struct cfq_queue **async_cfqq = NULL;
|
|
struct cfq_queue *cfqq = NULL;
|
|
|
|
if (!is_sync) {
|
|
async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
|
|
cfqq = *async_cfqq;
|
|
}
|
|
|
|
if (!cfqq) {
|
|
cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
|
|
if (!cfqq)
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* pin the queue now that it's allocated, scheduler exit will prune it
|
|
*/
|
|
if (!is_sync && !(*async_cfqq)) {
|
|
atomic_inc(&cfqq->ref);
|
|
*async_cfqq = cfqq;
|
|
}
|
|
|
|
atomic_inc(&cfqq->ref);
|
|
return cfqq;
|
|
}
|
|
|
|
/*
|
|
* We drop cfq io contexts lazily, so we may find a dead one.
|
|
*/
|
|
static void
|
|
cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
unsigned long flags;
|
|
|
|
WARN_ON(!list_empty(&cic->queue_list));
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
|
|
BUG_ON(ioc->ioc_data == cic);
|
|
|
|
radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
|
|
hlist_del_rcu(&cic->cic_list);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
cfq_cic_free(cic);
|
|
}
|
|
|
|
static struct cfq_io_context *
|
|
cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
|
|
{
|
|
struct cfq_io_context *cic;
|
|
unsigned long flags;
|
|
void *k;
|
|
|
|
if (unlikely(!ioc))
|
|
return NULL;
|
|
|
|
rcu_read_lock();
|
|
|
|
/*
|
|
* we maintain a last-hit cache, to avoid browsing over the tree
|
|
*/
|
|
cic = rcu_dereference(ioc->ioc_data);
|
|
if (cic && cic->key == cfqd) {
|
|
rcu_read_unlock();
|
|
return cic;
|
|
}
|
|
|
|
do {
|
|
cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
|
|
rcu_read_unlock();
|
|
if (!cic)
|
|
break;
|
|
/* ->key must be copied to avoid race with cfq_exit_queue() */
|
|
k = cic->key;
|
|
if (unlikely(!k)) {
|
|
cfq_drop_dead_cic(cfqd, ioc, cic);
|
|
rcu_read_lock();
|
|
continue;
|
|
}
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
rcu_assign_pointer(ioc->ioc_data, cic);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
break;
|
|
} while (1);
|
|
|
|
return cic;
|
|
}
|
|
|
|
/*
|
|
* Add cic into ioc, using cfqd as the search key. This enables us to lookup
|
|
* the process specific cfq io context when entered from the block layer.
|
|
* Also adds the cic to a per-cfqd list, used when this queue is removed.
|
|
*/
|
|
static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
|
|
struct cfq_io_context *cic, gfp_t gfp_mask)
|
|
{
|
|
unsigned long flags;
|
|
int ret;
|
|
|
|
ret = radix_tree_preload(gfp_mask);
|
|
if (!ret) {
|
|
cic->ioc = ioc;
|
|
cic->key = cfqd;
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
ret = radix_tree_insert(&ioc->radix_root,
|
|
(unsigned long) cfqd, cic);
|
|
if (!ret)
|
|
hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
radix_tree_preload_end();
|
|
|
|
if (!ret) {
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
list_add(&cic->queue_list, &cfqd->cic_list);
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
}
|
|
|
|
if (ret)
|
|
printk(KERN_ERR "cfq: cic link failed!\n");
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Setup general io context and cfq io context. There can be several cfq
|
|
* io contexts per general io context, if this process is doing io to more
|
|
* than one device managed by cfq.
|
|
*/
|
|
static struct cfq_io_context *
|
|
cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
|
|
{
|
|
struct io_context *ioc = NULL;
|
|
struct cfq_io_context *cic;
|
|
|
|
might_sleep_if(gfp_mask & __GFP_WAIT);
|
|
|
|
ioc = get_io_context(gfp_mask, cfqd->queue->node);
|
|
if (!ioc)
|
|
return NULL;
|
|
|
|
cic = cfq_cic_lookup(cfqd, ioc);
|
|
if (cic)
|
|
goto out;
|
|
|
|
cic = cfq_alloc_io_context(cfqd, gfp_mask);
|
|
if (cic == NULL)
|
|
goto err;
|
|
|
|
if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
|
|
goto err_free;
|
|
|
|
out:
|
|
smp_read_barrier_depends();
|
|
if (unlikely(ioc->ioprio_changed))
|
|
cfq_ioc_set_ioprio(ioc);
|
|
|
|
return cic;
|
|
err_free:
|
|
cfq_cic_free(cic);
|
|
err:
|
|
put_io_context(ioc);
|
|
return NULL;
|
|
}
|
|
|
|
static void
|
|
cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
|
|
{
|
|
unsigned long elapsed = jiffies - cic->last_end_request;
|
|
unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
|
|
|
|
cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
|
|
cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
|
|
cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
|
|
}
|
|
|
|
static void
|
|
cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
|
|
struct request *rq)
|
|
{
|
|
sector_t sdist;
|
|
u64 total;
|
|
|
|
if (!cic->last_request_pos)
|
|
sdist = 0;
|
|
else if (cic->last_request_pos < rq->sector)
|
|
sdist = rq->sector - cic->last_request_pos;
|
|
else
|
|
sdist = cic->last_request_pos - rq->sector;
|
|
|
|
/*
|
|
* Don't allow the seek distance to get too large from the
|
|
* odd fragment, pagein, etc
|
|
*/
|
|
if (cic->seek_samples <= 60) /* second&third seek */
|
|
sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
|
|
else
|
|
sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
|
|
|
|
cic->seek_samples = (7*cic->seek_samples + 256) / 8;
|
|
cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
|
|
total = cic->seek_total + (cic->seek_samples/2);
|
|
do_div(total, cic->seek_samples);
|
|
cic->seek_mean = (sector_t)total;
|
|
}
|
|
|
|
/*
|
|
* Disable idle window if the process thinks too long or seeks so much that
|
|
* it doesn't matter
|
|
*/
|
|
static void
|
|
cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct cfq_io_context *cic)
|
|
{
|
|
int old_idle, enable_idle;
|
|
|
|
/*
|
|
* Don't idle for async or idle io prio class
|
|
*/
|
|
if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
|
|
return;
|
|
|
|
enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
|
|
|
|
if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
|
|
(cfqd->hw_tag && CIC_SEEKY(cic)))
|
|
enable_idle = 0;
|
|
else if (sample_valid(cic->ttime_samples)) {
|
|
if (cic->ttime_mean > cfqd->cfq_slice_idle)
|
|
enable_idle = 0;
|
|
else
|
|
enable_idle = 1;
|
|
}
|
|
|
|
if (old_idle != enable_idle) {
|
|
cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
|
|
if (enable_idle)
|
|
cfq_mark_cfqq_idle_window(cfqq);
|
|
else
|
|
cfq_clear_cfqq_idle_window(cfqq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Check if new_cfqq should preempt the currently active queue. Return 0 for
|
|
* no or if we aren't sure, a 1 will cause a preempt.
|
|
*/
|
|
static int
|
|
cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
|
|
struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq;
|
|
|
|
cfqq = cfqd->active_queue;
|
|
if (!cfqq)
|
|
return 0;
|
|
|
|
if (cfq_slice_used(cfqq))
|
|
return 1;
|
|
|
|
if (cfq_class_idle(new_cfqq))
|
|
return 0;
|
|
|
|
if (cfq_class_idle(cfqq))
|
|
return 1;
|
|
|
|
/*
|
|
* if the new request is sync, but the currently running queue is
|
|
* not, let the sync request have priority.
|
|
*/
|
|
if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
|
|
return 1;
|
|
|
|
/*
|
|
* So both queues are sync. Let the new request get disk time if
|
|
* it's a metadata request and the current queue is doing regular IO.
|
|
*/
|
|
if (rq_is_meta(rq) && !cfqq->meta_pending)
|
|
return 1;
|
|
|
|
/*
|
|
* Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
|
|
*/
|
|
if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
|
|
return 1;
|
|
|
|
if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
|
|
return 0;
|
|
|
|
/*
|
|
* if this request is as-good as one we would expect from the
|
|
* current cfqq, let it preempt
|
|
*/
|
|
if (cfq_rq_close(cfqd, rq))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* cfqq preempts the active queue. if we allowed preempt with no slice left,
|
|
* let it have half of its nominal slice.
|
|
*/
|
|
static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
cfq_log_cfqq(cfqd, cfqq, "preempt");
|
|
cfq_slice_expired(cfqd, 1);
|
|
|
|
/*
|
|
* Put the new queue at the front of the of the current list,
|
|
* so we know that it will be selected next.
|
|
*/
|
|
BUG_ON(!cfq_cfqq_on_rr(cfqq));
|
|
|
|
cfq_service_tree_add(cfqd, cfqq, 1);
|
|
|
|
cfqq->slice_end = 0;
|
|
cfq_mark_cfqq_slice_new(cfqq);
|
|
}
|
|
|
|
/*
|
|
* Called when a new fs request (rq) is added (to cfqq). Check if there's
|
|
* something we should do about it
|
|
*/
|
|
static void
|
|
cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct request *rq)
|
|
{
|
|
struct cfq_io_context *cic = RQ_CIC(rq);
|
|
|
|
cfqd->rq_queued++;
|
|
if (rq_is_meta(rq))
|
|
cfqq->meta_pending++;
|
|
|
|
cfq_update_io_thinktime(cfqd, cic);
|
|
cfq_update_io_seektime(cfqd, cic, rq);
|
|
cfq_update_idle_window(cfqd, cfqq, cic);
|
|
|
|
cic->last_request_pos = rq->sector + rq->nr_sectors;
|
|
|
|
if (cfqq == cfqd->active_queue) {
|
|
/*
|
|
* Remember that we saw a request from this process, but
|
|
* don't start queuing just yet. Otherwise we risk seeing lots
|
|
* of tiny requests, because we disrupt the normal plugging
|
|
* and merging. If the request is already larger than a single
|
|
* page, let it rip immediately. For that case we assume that
|
|
* merging is already done. Ditto for a busy system that
|
|
* has other work pending, don't risk delaying until the
|
|
* idle timer unplug to continue working.
|
|
*/
|
|
if (cfq_cfqq_wait_request(cfqq)) {
|
|
if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
|
|
cfqd->busy_queues > 1) {
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
blk_start_queueing(cfqd->queue);
|
|
}
|
|
cfq_mark_cfqq_must_dispatch(cfqq);
|
|
}
|
|
} else if (cfq_should_preempt(cfqd, cfqq, rq)) {
|
|
/*
|
|
* not the active queue - expire current slice if it is
|
|
* idle and has expired it's mean thinktime or this new queue
|
|
* has some old slice time left and is of higher priority or
|
|
* this new queue is RT and the current one is BE
|
|
*/
|
|
cfq_preempt_queue(cfqd, cfqq);
|
|
blk_start_queueing(cfqd->queue);
|
|
}
|
|
}
|
|
|
|
static void cfq_insert_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
cfq_log_cfqq(cfqd, cfqq, "insert_request");
|
|
cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
|
|
|
|
cfq_add_rq_rb(rq);
|
|
|
|
list_add_tail(&rq->queuelist, &cfqq->fifo);
|
|
|
|
cfq_rq_enqueued(cfqd, cfqq, rq);
|
|
}
|
|
|
|
/*
|
|
* Update hw_tag based on peak queue depth over 50 samples under
|
|
* sufficient load.
|
|
*/
|
|
static void cfq_update_hw_tag(struct cfq_data *cfqd)
|
|
{
|
|
if (cfqd->rq_in_driver > cfqd->rq_in_driver_peak)
|
|
cfqd->rq_in_driver_peak = cfqd->rq_in_driver;
|
|
|
|
if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
|
|
cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
|
|
return;
|
|
|
|
if (cfqd->hw_tag_samples++ < 50)
|
|
return;
|
|
|
|
if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
|
|
cfqd->hw_tag = 1;
|
|
else
|
|
cfqd->hw_tag = 0;
|
|
|
|
cfqd->hw_tag_samples = 0;
|
|
cfqd->rq_in_driver_peak = 0;
|
|
}
|
|
|
|
static void cfq_completed_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
const int sync = rq_is_sync(rq);
|
|
unsigned long now;
|
|
|
|
now = jiffies;
|
|
cfq_log_cfqq(cfqd, cfqq, "complete");
|
|
|
|
cfq_update_hw_tag(cfqd);
|
|
|
|
WARN_ON(!cfqd->rq_in_driver);
|
|
WARN_ON(!cfqq->dispatched);
|
|
cfqd->rq_in_driver--;
|
|
cfqq->dispatched--;
|
|
|
|
if (cfq_cfqq_sync(cfqq))
|
|
cfqd->sync_flight--;
|
|
|
|
if (!cfq_class_idle(cfqq))
|
|
cfqd->last_end_request = now;
|
|
|
|
if (sync)
|
|
RQ_CIC(rq)->last_end_request = now;
|
|
|
|
/*
|
|
* If this is the active queue, check if it needs to be expired,
|
|
* or if we want to idle in case it has no pending requests.
|
|
*/
|
|
if (cfqd->active_queue == cfqq) {
|
|
const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
|
|
|
|
if (cfq_cfqq_slice_new(cfqq)) {
|
|
cfq_set_prio_slice(cfqd, cfqq);
|
|
cfq_clear_cfqq_slice_new(cfqq);
|
|
}
|
|
/*
|
|
* If there are no requests waiting in this queue, and
|
|
* there are other queues ready to issue requests, AND
|
|
* those other queues are issuing requests within our
|
|
* mean seek distance, give them a chance to run instead
|
|
* of idling.
|
|
*/
|
|
if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
|
|
cfq_slice_expired(cfqd, 1);
|
|
else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
|
|
sync && !rq_noidle(rq))
|
|
cfq_arm_slice_timer(cfqd);
|
|
}
|
|
|
|
if (!cfqd->rq_in_driver)
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
|
|
/*
|
|
* we temporarily boost lower priority queues if they are holding fs exclusive
|
|
* resources. they are boosted to normal prio (CLASS_BE/4)
|
|
*/
|
|
static void cfq_prio_boost(struct cfq_queue *cfqq)
|
|
{
|
|
if (has_fs_excl()) {
|
|
/*
|
|
* boost idle prio on transactions that would lock out other
|
|
* users of the filesystem
|
|
*/
|
|
if (cfq_class_idle(cfqq))
|
|
cfqq->ioprio_class = IOPRIO_CLASS_BE;
|
|
if (cfqq->ioprio > IOPRIO_NORM)
|
|
cfqq->ioprio = IOPRIO_NORM;
|
|
} else {
|
|
/*
|
|
* check if we need to unboost the queue
|
|
*/
|
|
if (cfqq->ioprio_class != cfqq->org_ioprio_class)
|
|
cfqq->ioprio_class = cfqq->org_ioprio_class;
|
|
if (cfqq->ioprio != cfqq->org_ioprio)
|
|
cfqq->ioprio = cfqq->org_ioprio;
|
|
}
|
|
}
|
|
|
|
static inline int __cfq_may_queue(struct cfq_queue *cfqq)
|
|
{
|
|
if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
|
|
!cfq_cfqq_must_alloc_slice(cfqq)) {
|
|
cfq_mark_cfqq_must_alloc_slice(cfqq);
|
|
return ELV_MQUEUE_MUST;
|
|
}
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
|
|
static int cfq_may_queue(struct request_queue *q, int rw)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct task_struct *tsk = current;
|
|
struct cfq_io_context *cic;
|
|
struct cfq_queue *cfqq;
|
|
|
|
/*
|
|
* don't force setup of a queue from here, as a call to may_queue
|
|
* does not necessarily imply that a request actually will be queued.
|
|
* so just lookup a possibly existing queue, or return 'may queue'
|
|
* if that fails
|
|
*/
|
|
cic = cfq_cic_lookup(cfqd, tsk->io_context);
|
|
if (!cic)
|
|
return ELV_MQUEUE_MAY;
|
|
|
|
cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
|
|
if (cfqq) {
|
|
cfq_init_prio_data(cfqq, cic->ioc);
|
|
cfq_prio_boost(cfqq);
|
|
|
|
return __cfq_may_queue(cfqq);
|
|
}
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
|
|
/*
|
|
* queue lock held here
|
|
*/
|
|
static void cfq_put_request(struct request *rq)
|
|
{
|
|
struct cfq_queue *cfqq = RQ_CFQQ(rq);
|
|
|
|
if (cfqq) {
|
|
const int rw = rq_data_dir(rq);
|
|
|
|
BUG_ON(!cfqq->allocated[rw]);
|
|
cfqq->allocated[rw]--;
|
|
|
|
put_io_context(RQ_CIC(rq)->ioc);
|
|
|
|
rq->elevator_private = NULL;
|
|
rq->elevator_private2 = NULL;
|
|
|
|
cfq_put_queue(cfqq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate cfq data structures associated with this request.
|
|
*/
|
|
static int
|
|
cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_io_context *cic;
|
|
const int rw = rq_data_dir(rq);
|
|
const int is_sync = rq_is_sync(rq);
|
|
struct cfq_queue *cfqq;
|
|
unsigned long flags;
|
|
|
|
might_sleep_if(gfp_mask & __GFP_WAIT);
|
|
|
|
cic = cfq_get_io_context(cfqd, gfp_mask);
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
if (!cic)
|
|
goto queue_fail;
|
|
|
|
cfqq = cic_to_cfqq(cic, is_sync);
|
|
if (!cfqq) {
|
|
cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
|
|
|
|
if (!cfqq)
|
|
goto queue_fail;
|
|
|
|
cic_set_cfqq(cic, cfqq, is_sync);
|
|
}
|
|
|
|
cfqq->allocated[rw]++;
|
|
cfq_clear_cfqq_must_alloc(cfqq);
|
|
atomic_inc(&cfqq->ref);
|
|
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
|
|
rq->elevator_private = cic;
|
|
rq->elevator_private2 = cfqq;
|
|
return 0;
|
|
|
|
queue_fail:
|
|
if (cic)
|
|
put_io_context(cic->ioc);
|
|
|
|
cfq_schedule_dispatch(cfqd);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
cfq_log(cfqd, "set_request fail");
|
|
return 1;
|
|
}
|
|
|
|
static void cfq_kick_queue(struct work_struct *work)
|
|
{
|
|
struct cfq_data *cfqd =
|
|
container_of(work, struct cfq_data, unplug_work);
|
|
struct request_queue *q = cfqd->queue;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
blk_start_queueing(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
|
|
/*
|
|
* Timer running if the active_queue is currently idling inside its time slice
|
|
*/
|
|
static void cfq_idle_slice_timer(unsigned long data)
|
|
{
|
|
struct cfq_data *cfqd = (struct cfq_data *) data;
|
|
struct cfq_queue *cfqq;
|
|
unsigned long flags;
|
|
int timed_out = 1;
|
|
|
|
cfq_log(cfqd, "idle timer fired");
|
|
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
|
|
cfqq = cfqd->active_queue;
|
|
if (cfqq) {
|
|
timed_out = 0;
|
|
|
|
/*
|
|
* We saw a request before the queue expired, let it through
|
|
*/
|
|
if (cfq_cfqq_must_dispatch(cfqq))
|
|
goto out_kick;
|
|
|
|
/*
|
|
* expired
|
|
*/
|
|
if (cfq_slice_used(cfqq))
|
|
goto expire;
|
|
|
|
/*
|
|
* only expire and reinvoke request handler, if there are
|
|
* other queues with pending requests
|
|
*/
|
|
if (!cfqd->busy_queues)
|
|
goto out_cont;
|
|
|
|
/*
|
|
* not expired and it has a request pending, let it dispatch
|
|
*/
|
|
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
|
|
goto out_kick;
|
|
}
|
|
expire:
|
|
cfq_slice_expired(cfqd, timed_out);
|
|
out_kick:
|
|
cfq_schedule_dispatch(cfqd);
|
|
out_cont:
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
|
|
static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
|
|
{
|
|
del_timer_sync(&cfqd->idle_slice_timer);
|
|
cancel_work_sync(&cfqd->unplug_work);
|
|
}
|
|
|
|
static void cfq_put_async_queues(struct cfq_data *cfqd)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < IOPRIO_BE_NR; i++) {
|
|
if (cfqd->async_cfqq[0][i])
|
|
cfq_put_queue(cfqd->async_cfqq[0][i]);
|
|
if (cfqd->async_cfqq[1][i])
|
|
cfq_put_queue(cfqd->async_cfqq[1][i]);
|
|
}
|
|
|
|
if (cfqd->async_idle_cfqq)
|
|
cfq_put_queue(cfqd->async_idle_cfqq);
|
|
}
|
|
|
|
static void cfq_exit_queue(struct elevator_queue *e)
|
|
{
|
|
struct cfq_data *cfqd = e->elevator_data;
|
|
struct request_queue *q = cfqd->queue;
|
|
|
|
cfq_shutdown_timer_wq(cfqd);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
if (cfqd->active_queue)
|
|
__cfq_slice_expired(cfqd, cfqd->active_queue, 0);
|
|
|
|
while (!list_empty(&cfqd->cic_list)) {
|
|
struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
|
|
struct cfq_io_context,
|
|
queue_list);
|
|
|
|
__cfq_exit_single_io_context(cfqd, cic);
|
|
}
|
|
|
|
cfq_put_async_queues(cfqd);
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
cfq_shutdown_timer_wq(cfqd);
|
|
|
|
kfree(cfqd);
|
|
}
|
|
|
|
static void *cfq_init_queue(struct request_queue *q)
|
|
{
|
|
struct cfq_data *cfqd;
|
|
int i;
|
|
|
|
cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
|
|
if (!cfqd)
|
|
return NULL;
|
|
|
|
cfqd->service_tree = CFQ_RB_ROOT;
|
|
|
|
/*
|
|
* Not strictly needed (since RB_ROOT just clears the node and we
|
|
* zeroed cfqd on alloc), but better be safe in case someone decides
|
|
* to add magic to the rb code
|
|
*/
|
|
for (i = 0; i < CFQ_PRIO_LISTS; i++)
|
|
cfqd->prio_trees[i] = RB_ROOT;
|
|
|
|
INIT_LIST_HEAD(&cfqd->cic_list);
|
|
|
|
cfqd->queue = q;
|
|
|
|
init_timer(&cfqd->idle_slice_timer);
|
|
cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
|
|
cfqd->idle_slice_timer.data = (unsigned long) cfqd;
|
|
|
|
INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
|
|
|
|
cfqd->last_end_request = jiffies;
|
|
cfqd->cfq_quantum = cfq_quantum;
|
|
cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
|
|
cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
|
|
cfqd->cfq_back_max = cfq_back_max;
|
|
cfqd->cfq_back_penalty = cfq_back_penalty;
|
|
cfqd->cfq_slice[0] = cfq_slice_async;
|
|
cfqd->cfq_slice[1] = cfq_slice_sync;
|
|
cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
|
|
cfqd->cfq_slice_idle = cfq_slice_idle;
|
|
cfqd->hw_tag = 1;
|
|
|
|
return cfqd;
|
|
}
|
|
|
|
static void cfq_slab_kill(void)
|
|
{
|
|
/*
|
|
* Caller already ensured that pending RCU callbacks are completed,
|
|
* so we should have no busy allocations at this point.
|
|
*/
|
|
if (cfq_pool)
|
|
kmem_cache_destroy(cfq_pool);
|
|
if (cfq_ioc_pool)
|
|
kmem_cache_destroy(cfq_ioc_pool);
|
|
}
|
|
|
|
static int __init cfq_slab_setup(void)
|
|
{
|
|
cfq_pool = KMEM_CACHE(cfq_queue, 0);
|
|
if (!cfq_pool)
|
|
goto fail;
|
|
|
|
cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
|
|
if (!cfq_ioc_pool)
|
|
goto fail;
|
|
|
|
return 0;
|
|
fail:
|
|
cfq_slab_kill();
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* sysfs parts below -->
|
|
*/
|
|
static ssize_t
|
|
cfq_var_show(unsigned int var, char *page)
|
|
{
|
|
return sprintf(page, "%d\n", var);
|
|
}
|
|
|
|
static ssize_t
|
|
cfq_var_store(unsigned int *var, const char *page, size_t count)
|
|
{
|
|
char *p = (char *) page;
|
|
|
|
*var = simple_strtoul(p, &p, 10);
|
|
return count;
|
|
}
|
|
|
|
#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
|
|
static ssize_t __FUNC(struct elevator_queue *e, char *page) \
|
|
{ \
|
|
struct cfq_data *cfqd = e->elevator_data; \
|
|
unsigned int __data = __VAR; \
|
|
if (__CONV) \
|
|
__data = jiffies_to_msecs(__data); \
|
|
return cfq_var_show(__data, (page)); \
|
|
}
|
|
SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
|
|
SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
|
|
SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
|
|
SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
|
|
SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
|
|
SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
|
|
SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
|
|
SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
|
|
SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
|
|
#undef SHOW_FUNCTION
|
|
|
|
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
|
|
static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
|
|
{ \
|
|
struct cfq_data *cfqd = e->elevator_data; \
|
|
unsigned int __data; \
|
|
int ret = cfq_var_store(&__data, (page), count); \
|
|
if (__data < (MIN)) \
|
|
__data = (MIN); \
|
|
else if (__data > (MAX)) \
|
|
__data = (MAX); \
|
|
if (__CONV) \
|
|
*(__PTR) = msecs_to_jiffies(__data); \
|
|
else \
|
|
*(__PTR) = __data; \
|
|
return ret; \
|
|
}
|
|
STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
|
|
STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
|
|
UINT_MAX, 1);
|
|
STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
|
|
UINT_MAX, 1);
|
|
STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
|
|
STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
|
|
UINT_MAX, 0);
|
|
STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
|
|
STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
|
|
STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
|
|
STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
|
|
UINT_MAX, 0);
|
|
#undef STORE_FUNCTION
|
|
|
|
#define CFQ_ATTR(name) \
|
|
__ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
|
|
|
|
static struct elv_fs_entry cfq_attrs[] = {
|
|
CFQ_ATTR(quantum),
|
|
CFQ_ATTR(fifo_expire_sync),
|
|
CFQ_ATTR(fifo_expire_async),
|
|
CFQ_ATTR(back_seek_max),
|
|
CFQ_ATTR(back_seek_penalty),
|
|
CFQ_ATTR(slice_sync),
|
|
CFQ_ATTR(slice_async),
|
|
CFQ_ATTR(slice_async_rq),
|
|
CFQ_ATTR(slice_idle),
|
|
__ATTR_NULL
|
|
};
|
|
|
|
static struct elevator_type iosched_cfq = {
|
|
.ops = {
|
|
.elevator_merge_fn = cfq_merge,
|
|
.elevator_merged_fn = cfq_merged_request,
|
|
.elevator_merge_req_fn = cfq_merged_requests,
|
|
.elevator_allow_merge_fn = cfq_allow_merge,
|
|
.elevator_dispatch_fn = cfq_dispatch_requests,
|
|
.elevator_add_req_fn = cfq_insert_request,
|
|
.elevator_activate_req_fn = cfq_activate_request,
|
|
.elevator_deactivate_req_fn = cfq_deactivate_request,
|
|
.elevator_queue_empty_fn = cfq_queue_empty,
|
|
.elevator_completed_req_fn = cfq_completed_request,
|
|
.elevator_former_req_fn = elv_rb_former_request,
|
|
.elevator_latter_req_fn = elv_rb_latter_request,
|
|
.elevator_set_req_fn = cfq_set_request,
|
|
.elevator_put_req_fn = cfq_put_request,
|
|
.elevator_may_queue_fn = cfq_may_queue,
|
|
.elevator_init_fn = cfq_init_queue,
|
|
.elevator_exit_fn = cfq_exit_queue,
|
|
.trim = cfq_free_io_context,
|
|
},
|
|
.elevator_attrs = cfq_attrs,
|
|
.elevator_name = "cfq",
|
|
.elevator_owner = THIS_MODULE,
|
|
};
|
|
|
|
static int __init cfq_init(void)
|
|
{
|
|
/*
|
|
* could be 0 on HZ < 1000 setups
|
|
*/
|
|
if (!cfq_slice_async)
|
|
cfq_slice_async = 1;
|
|
if (!cfq_slice_idle)
|
|
cfq_slice_idle = 1;
|
|
|
|
if (cfq_slab_setup())
|
|
return -ENOMEM;
|
|
|
|
elv_register(&iosched_cfq);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __exit cfq_exit(void)
|
|
{
|
|
DECLARE_COMPLETION_ONSTACK(all_gone);
|
|
elv_unregister(&iosched_cfq);
|
|
ioc_gone = &all_gone;
|
|
/* ioc_gone's update must be visible before reading ioc_count */
|
|
smp_wmb();
|
|
|
|
/*
|
|
* this also protects us from entering cfq_slab_kill() with
|
|
* pending RCU callbacks
|
|
*/
|
|
if (elv_ioc_count_read(ioc_count))
|
|
wait_for_completion(&all_gone);
|
|
cfq_slab_kill();
|
|
}
|
|
|
|
module_init(cfq_init);
|
|
module_exit(cfq_exit);
|
|
|
|
MODULE_AUTHOR("Jens Axboe");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
|