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![Arjan van de Ven](/assets/img/avatar_default.png)
the patch below marks various read-only variables in block/* as const, so that gcc can optimize the use of them; eg gcc will replace the use by the value directly now and will even remove the memory usage of these. Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Jens Axboe <axboe@suse.de>
2462 lines
58 KiB
C
2462 lines
58 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@suse.de>
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*/
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/elevator.h>
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#include <linux/bio.h>
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/compiler.h>
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#include <linux/hash.h>
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#include <linux/rbtree.h>
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#include <linux/mempool.h>
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#include <linux/ioprio.h>
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#include <linux/writeback.h>
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/*
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* tunables
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*/
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static const int cfq_quantum = 4; /* max queue in one round of service */
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static const int cfq_queued = 8; /* minimum rq allocate limit per-queue*/
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static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
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static const int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */
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static const int cfq_back_penalty = 2; /* penalty of a backwards seek */
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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 / 100;
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#define CFQ_IDLE_GRACE (HZ / 10)
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#define CFQ_SLICE_SCALE (5)
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#define CFQ_KEY_ASYNC (0)
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#define CFQ_KEY_ANY (0xffff)
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/*
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* disable queueing at the driver/hardware level
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*/
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static const int cfq_max_depth = 2;
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/*
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* for the hash of cfqq inside the cfqd
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*/
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#define CFQ_QHASH_SHIFT 6
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#define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT)
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#define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash)
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/*
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* for the hash of crq inside the cfqq
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*/
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#define CFQ_MHASH_SHIFT 6
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#define CFQ_MHASH_BLOCK(sec) ((sec) >> 3)
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#define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT)
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#define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT)
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#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
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#define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash)
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#define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list)
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#define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
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#define RQ_DATA(rq) (rq)->elevator_private
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/*
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* rb-tree defines
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*/
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#define RB_NONE (2)
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#define RB_EMPTY(node) ((node)->rb_node == NULL)
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#define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE
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#define RB_CLEAR(node) do { \
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(node)->rb_parent = NULL; \
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RB_CLEAR_COLOR((node)); \
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(node)->rb_right = NULL; \
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(node)->rb_left = NULL; \
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} while (0)
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#define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL)
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#define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
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#define rq_rb_key(rq) (rq)->sector
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static kmem_cache_t *crq_pool;
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static kmem_cache_t *cfq_pool;
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static kmem_cache_t *cfq_ioc_pool;
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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_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
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#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
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#define ASYNC (0)
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#define SYNC (1)
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#define cfq_cfqq_dispatched(cfqq) \
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((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC])
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#define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC)
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#define cfq_cfqq_sync(cfqq) \
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(cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
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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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atomic_t ref;
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request_queue_t *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 list_head rr_list[CFQ_PRIO_LISTS];
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struct list_head busy_rr;
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struct list_head cur_rr;
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struct list_head idle_rr;
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unsigned int busy_queues;
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/*
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* non-ordered list of empty cfqq's
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*/
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struct list_head empty_list;
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/*
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* cfqq lookup hash
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*/
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struct hlist_head *cfq_hash;
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/*
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* global crq hash for all queues
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*/
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struct hlist_head *crq_hash;
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unsigned int max_queued;
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mempool_t *crq_pool;
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int rq_in_driver;
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/*
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* schedule slice state info
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*/
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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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int cur_prio, cur_end_prio;
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unsigned int dispatch_slice;
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struct timer_list idle_class_timer;
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sector_t last_sector;
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unsigned long last_end_request;
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unsigned int rq_starved;
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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_queued;
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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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unsigned int cfq_max_depth;
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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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/* parent cfq_data */
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struct cfq_data *cfqd;
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/* cfqq lookup hash */
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struct hlist_node cfq_hash;
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/* hash key */
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unsigned int key;
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/* on either rr or empty list of cfqd */
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struct list_head cfq_list;
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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 cfq_rq *next_crq;
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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_start;
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unsigned long slice_end;
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unsigned long slice_left;
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unsigned long service_last;
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/* number of requests that are on the dispatch list */
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int on_dispatch[2];
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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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/* various state flags, see below */
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unsigned int flags;
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};
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struct cfq_rq {
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struct rb_node rb_node;
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sector_t rb_key;
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struct request *request;
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struct hlist_node hash;
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struct cfq_queue *cfq_queue;
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struct cfq_io_context *io_context;
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unsigned int crq_flags;
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};
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enum cfqq_state_flags {
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CFQ_CFQQ_FLAG_on_rr = 0,
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CFQ_CFQQ_FLAG_wait_request,
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CFQ_CFQQ_FLAG_must_alloc,
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CFQ_CFQQ_FLAG_must_alloc_slice,
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CFQ_CFQQ_FLAG_must_dispatch,
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CFQ_CFQQ_FLAG_fifo_expire,
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CFQ_CFQQ_FLAG_idle_window,
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CFQ_CFQQ_FLAG_prio_changed,
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CFQ_CFQQ_FLAG_expired,
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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_alloc);
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CFQ_CFQQ_FNS(must_alloc_slice);
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CFQ_CFQQ_FNS(must_dispatch);
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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(expired);
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#undef CFQ_CFQQ_FNS
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enum cfq_rq_state_flags {
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CFQ_CRQ_FLAG_is_sync = 0,
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};
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#define CFQ_CRQ_FNS(name) \
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static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \
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{ \
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crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \
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} \
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static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \
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{ \
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crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \
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} \
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static inline int cfq_crq_##name(const struct cfq_rq *crq) \
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{ \
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return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
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}
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CFQ_CRQ_FNS(is_sync);
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#undef CFQ_CRQ_FNS
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static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short);
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static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *);
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static void cfq_put_cfqd(struct cfq_data *cfqd);
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#define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
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/*
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* lots of deadline iosched dupes, can be abstracted later...
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*/
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static inline void cfq_del_crq_hash(struct cfq_rq *crq)
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{
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hlist_del_init(&crq->hash);
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}
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static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq)
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{
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const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request));
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hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]);
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}
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static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset)
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{
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struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)];
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struct hlist_node *entry, *next;
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hlist_for_each_safe(entry, next, hash_list) {
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struct cfq_rq *crq = list_entry_hash(entry);
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struct request *__rq = crq->request;
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if (!rq_mergeable(__rq)) {
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cfq_del_crq_hash(crq);
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continue;
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}
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if (rq_hash_key(__rq) == offset)
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return __rq;
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}
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return NULL;
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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->rq_in_driver && cfqd->busy_queues)
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kblockd_schedule_work(&cfqd->unplug_work);
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}
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static int cfq_queue_empty(request_queue_t *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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* Lifted from AS - choose which of crq1 and crq2 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 are penalized and only allowed to a certain extent.
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*/
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static struct cfq_rq *
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cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2)
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{
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sector_t last, s1, s2, d1 = 0, d2 = 0;
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int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */
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unsigned long back_max;
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if (crq1 == NULL || crq1 == crq2)
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return crq2;
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if (crq2 == NULL)
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return crq1;
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if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2))
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return crq1;
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else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1))
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return crq2;
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s1 = crq1->request->sector;
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s2 = crq2->request->sector;
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last = cfqd->last_sector;
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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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r1_wrap = 1;
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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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r2_wrap = 1;
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/* Found required data */
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if (!r1_wrap && r2_wrap)
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return crq1;
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else if (!r2_wrap && r1_wrap)
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return crq2;
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else if (r1_wrap && r2_wrap) {
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/* both behind the head */
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if (s1 <= s2)
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return crq1;
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else
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return crq2;
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}
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/* Both requests in front of the head */
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if (d1 < d2)
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return crq1;
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else if (d2 < d1)
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return crq2;
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else {
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if (s1 >= s2)
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return crq1;
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else
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return crq2;
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}
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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 cfq_rq *
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cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
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struct cfq_rq *last)
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{
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struct cfq_rq *crq_next = NULL, *crq_prev = NULL;
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struct rb_node *rbnext, *rbprev;
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if (!(rbnext = rb_next(&last->rb_node))) {
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rbnext = rb_first(&cfqq->sort_list);
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if (rbnext == &last->rb_node)
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rbnext = NULL;
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}
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rbprev = rb_prev(&last->rb_node);
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if (rbprev)
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crq_prev = rb_entry_crq(rbprev);
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if (rbnext)
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crq_next = rb_entry_crq(rbnext);
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return cfq_choose_req(cfqd, crq_next, crq_prev);
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}
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static void cfq_update_next_crq(struct cfq_rq *crq)
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{
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struct cfq_queue *cfqq = crq->cfq_queue;
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if (cfqq->next_crq == crq)
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cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq);
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}
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static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
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{
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struct cfq_data *cfqd = cfqq->cfqd;
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struct list_head *list, *entry;
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BUG_ON(!cfq_cfqq_on_rr(cfqq));
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list_del(&cfqq->cfq_list);
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if (cfq_class_rt(cfqq))
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list = &cfqd->cur_rr;
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else if (cfq_class_idle(cfqq))
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list = &cfqd->idle_rr;
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else {
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/*
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* if cfqq has requests in flight, don't allow it to be
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* found in cfq_set_active_queue before it has finished them.
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* this is done to increase fairness between a process that
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* has lots of io pending vs one that only generates one
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* sporadically or synchronously
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*/
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if (cfq_cfqq_dispatched(cfqq))
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list = &cfqd->busy_rr;
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else
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list = &cfqd->rr_list[cfqq->ioprio];
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}
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/*
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* if queue was preempted, just add to front to be fair. busy_rr
|
|
* isn't sorted.
|
|
*/
|
|
if (preempted || list == &cfqd->busy_rr) {
|
|
list_add(&cfqq->cfq_list, list);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* sort by when queue was last serviced
|
|
*/
|
|
entry = list;
|
|
while ((entry = entry->prev) != list) {
|
|
struct cfq_queue *__cfqq = list_entry_cfqq(entry);
|
|
|
|
if (!__cfqq->service_last)
|
|
break;
|
|
if (time_before(__cfqq->service_last, cfqq->service_last))
|
|
break;
|
|
}
|
|
|
|
list_add(&cfqq->cfq_list, entry);
|
|
}
|
|
|
|
/*
|
|
* add to busy list of queues for service, trying to be fair in ordering
|
|
* the pending list according to last request service
|
|
*/
|
|
static inline void
|
|
cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
BUG_ON(cfq_cfqq_on_rr(cfqq));
|
|
cfq_mark_cfqq_on_rr(cfqq);
|
|
cfqd->busy_queues++;
|
|
|
|
cfq_resort_rr_list(cfqq, 0);
|
|
}
|
|
|
|
static inline void
|
|
cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
BUG_ON(!cfq_cfqq_on_rr(cfqq));
|
|
cfq_clear_cfqq_on_rr(cfqq);
|
|
list_move(&cfqq->cfq_list, &cfqd->empty_list);
|
|
|
|
BUG_ON(!cfqd->busy_queues);
|
|
cfqd->busy_queues--;
|
|
}
|
|
|
|
/*
|
|
* rb tree support functions
|
|
*/
|
|
static inline void cfq_del_crq_rb(struct cfq_rq *crq)
|
|
{
|
|
struct cfq_queue *cfqq = crq->cfq_queue;
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
const int sync = cfq_crq_is_sync(crq);
|
|
|
|
BUG_ON(!cfqq->queued[sync]);
|
|
cfqq->queued[sync]--;
|
|
|
|
cfq_update_next_crq(crq);
|
|
|
|
rb_erase(&crq->rb_node, &cfqq->sort_list);
|
|
RB_CLEAR_COLOR(&crq->rb_node);
|
|
|
|
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list))
|
|
cfq_del_cfqq_rr(cfqd, cfqq);
|
|
}
|
|
|
|
static struct cfq_rq *
|
|
__cfq_add_crq_rb(struct cfq_rq *crq)
|
|
{
|
|
struct rb_node **p = &crq->cfq_queue->sort_list.rb_node;
|
|
struct rb_node *parent = NULL;
|
|
struct cfq_rq *__crq;
|
|
|
|
while (*p) {
|
|
parent = *p;
|
|
__crq = rb_entry_crq(parent);
|
|
|
|
if (crq->rb_key < __crq->rb_key)
|
|
p = &(*p)->rb_left;
|
|
else if (crq->rb_key > __crq->rb_key)
|
|
p = &(*p)->rb_right;
|
|
else
|
|
return __crq;
|
|
}
|
|
|
|
rb_link_node(&crq->rb_node, parent, p);
|
|
return NULL;
|
|
}
|
|
|
|
static void cfq_add_crq_rb(struct cfq_rq *crq)
|
|
{
|
|
struct cfq_queue *cfqq = crq->cfq_queue;
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
struct request *rq = crq->request;
|
|
struct cfq_rq *__alias;
|
|
|
|
crq->rb_key = rq_rb_key(rq);
|
|
cfqq->queued[cfq_crq_is_sync(crq)]++;
|
|
|
|
/*
|
|
* looks a little odd, but the first insert might return an alias.
|
|
* if that happens, put the alias on the dispatch list
|
|
*/
|
|
while ((__alias = __cfq_add_crq_rb(crq)) != NULL)
|
|
cfq_dispatch_insert(cfqd->queue, __alias);
|
|
|
|
rb_insert_color(&crq->rb_node, &cfqq->sort_list);
|
|
|
|
if (!cfq_cfqq_on_rr(cfqq))
|
|
cfq_add_cfqq_rr(cfqd, cfqq);
|
|
|
|
/*
|
|
* check if this request is a better next-serve candidate
|
|
*/
|
|
cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
|
|
}
|
|
|
|
static inline void
|
|
cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq)
|
|
{
|
|
rb_erase(&crq->rb_node, &cfqq->sort_list);
|
|
cfqq->queued[cfq_crq_is_sync(crq)]--;
|
|
|
|
cfq_add_crq_rb(crq);
|
|
}
|
|
|
|
static struct request *cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector)
|
|
|
|
{
|
|
struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid, CFQ_KEY_ANY);
|
|
struct rb_node *n;
|
|
|
|
if (!cfqq)
|
|
goto out;
|
|
|
|
n = cfqq->sort_list.rb_node;
|
|
while (n) {
|
|
struct cfq_rq *crq = rb_entry_crq(n);
|
|
|
|
if (sector < crq->rb_key)
|
|
n = n->rb_left;
|
|
else if (sector > crq->rb_key)
|
|
n = n->rb_right;
|
|
else
|
|
return crq->request;
|
|
}
|
|
|
|
out:
|
|
return NULL;
|
|
}
|
|
|
|
static void cfq_activate_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
|
|
cfqd->rq_in_driver++;
|
|
}
|
|
|
|
static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
|
|
WARN_ON(!cfqd->rq_in_driver);
|
|
cfqd->rq_in_driver--;
|
|
}
|
|
|
|
static void cfq_remove_request(struct request *rq)
|
|
{
|
|
struct cfq_rq *crq = RQ_DATA(rq);
|
|
|
|
list_del_init(&rq->queuelist);
|
|
cfq_del_crq_rb(crq);
|
|
cfq_del_crq_hash(crq);
|
|
}
|
|
|
|
static int
|
|
cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct request *__rq;
|
|
int ret;
|
|
|
|
__rq = cfq_find_rq_hash(cfqd, bio->bi_sector);
|
|
if (__rq && elv_rq_merge_ok(__rq, bio)) {
|
|
ret = ELEVATOR_BACK_MERGE;
|
|
goto out;
|
|
}
|
|
|
|
__rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio));
|
|
if (__rq && elv_rq_merge_ok(__rq, bio)) {
|
|
ret = ELEVATOR_FRONT_MERGE;
|
|
goto out;
|
|
}
|
|
|
|
return ELEVATOR_NO_MERGE;
|
|
out:
|
|
*req = __rq;
|
|
return ret;
|
|
}
|
|
|
|
static void cfq_merged_request(request_queue_t *q, struct request *req)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_rq *crq = RQ_DATA(req);
|
|
|
|
cfq_del_crq_hash(crq);
|
|
cfq_add_crq_hash(cfqd, crq);
|
|
|
|
if (rq_rb_key(req) != crq->rb_key) {
|
|
struct cfq_queue *cfqq = crq->cfq_queue;
|
|
|
|
cfq_update_next_crq(crq);
|
|
cfq_reposition_crq_rb(cfqq, crq);
|
|
}
|
|
}
|
|
|
|
static void
|
|
cfq_merged_requests(request_queue_t *q, struct request *rq,
|
|
struct request *next)
|
|
{
|
|
cfq_merged_request(q, rq);
|
|
|
|
/*
|
|
* 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 inline void
|
|
__cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
if (cfqq) {
|
|
/*
|
|
* stop potential idle class queues waiting service
|
|
*/
|
|
del_timer(&cfqd->idle_class_timer);
|
|
|
|
cfqq->slice_start = jiffies;
|
|
cfqq->slice_end = 0;
|
|
cfqq->slice_left = 0;
|
|
cfq_clear_cfqq_must_alloc_slice(cfqq);
|
|
cfq_clear_cfqq_fifo_expire(cfqq);
|
|
cfq_clear_cfqq_expired(cfqq);
|
|
}
|
|
|
|
cfqd->active_queue = cfqq;
|
|
}
|
|
|
|
/*
|
|
* 0
|
|
* 0,1
|
|
* 0,1,2
|
|
* 0,1,2,3
|
|
* 0,1,2,3,4
|
|
* 0,1,2,3,4,5
|
|
* 0,1,2,3,4,5,6
|
|
* 0,1,2,3,4,5,6,7
|
|
*/
|
|
static int cfq_get_next_prio_level(struct cfq_data *cfqd)
|
|
{
|
|
int prio, wrap;
|
|
|
|
prio = -1;
|
|
wrap = 0;
|
|
do {
|
|
int p;
|
|
|
|
for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) {
|
|
if (!list_empty(&cfqd->rr_list[p])) {
|
|
prio = p;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (prio != -1)
|
|
break;
|
|
cfqd->cur_prio = 0;
|
|
if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) {
|
|
cfqd->cur_end_prio = 0;
|
|
if (wrap)
|
|
break;
|
|
wrap = 1;
|
|
}
|
|
} while (1);
|
|
|
|
if (unlikely(prio == -1))
|
|
return -1;
|
|
|
|
BUG_ON(prio >= CFQ_PRIO_LISTS);
|
|
|
|
list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr);
|
|
|
|
cfqd->cur_prio = prio + 1;
|
|
if (cfqd->cur_prio > cfqd->cur_end_prio) {
|
|
cfqd->cur_end_prio = cfqd->cur_prio;
|
|
cfqd->cur_prio = 0;
|
|
}
|
|
if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) {
|
|
cfqd->cur_prio = 0;
|
|
cfqd->cur_end_prio = 0;
|
|
}
|
|
|
|
return prio;
|
|
}
|
|
|
|
static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
|
|
{
|
|
struct cfq_queue *cfqq;
|
|
|
|
/*
|
|
* if current queue is expired but not done with its requests yet,
|
|
* wait for that to happen
|
|
*/
|
|
if ((cfqq = cfqd->active_queue) != NULL) {
|
|
if (cfq_cfqq_expired(cfqq) && cfq_cfqq_dispatched(cfqq))
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* if current list is non-empty, grab first entry. if it is empty,
|
|
* get next prio level and grab first entry then if any are spliced
|
|
*/
|
|
if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1)
|
|
cfqq = list_entry_cfqq(cfqd->cur_rr.next);
|
|
|
|
/*
|
|
* if we have idle queues and no rt or be queues had pending
|
|
* requests, either allow immediate service if the grace period
|
|
* has passed or arm the idle grace timer
|
|
*/
|
|
if (!cfqq && !list_empty(&cfqd->idle_rr)) {
|
|
unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE;
|
|
|
|
if (time_after_eq(jiffies, end))
|
|
cfqq = list_entry_cfqq(cfqd->idle_rr.next);
|
|
else
|
|
mod_timer(&cfqd->idle_class_timer, end);
|
|
}
|
|
|
|
__cfq_set_active_queue(cfqd, cfqq);
|
|
return 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 preempted)
|
|
{
|
|
unsigned long now = jiffies;
|
|
|
|
if (cfq_cfqq_wait_request(cfqq))
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
|
|
if (!preempted && !cfq_cfqq_dispatched(cfqq))
|
|
cfqq->service_last = now;
|
|
|
|
cfq_clear_cfqq_must_dispatch(cfqq);
|
|
cfq_clear_cfqq_wait_request(cfqq);
|
|
|
|
/*
|
|
* store what was left of this slice, if the queue idled out
|
|
* or was preempted
|
|
*/
|
|
if (time_after(cfqq->slice_end, now))
|
|
cfqq->slice_left = cfqq->slice_end - now;
|
|
else
|
|
cfqq->slice_left = 0;
|
|
|
|
if (cfq_cfqq_on_rr(cfqq))
|
|
cfq_resort_rr_list(cfqq, preempted);
|
|
|
|
if (cfqq == cfqd->active_queue)
|
|
cfqd->active_queue = NULL;
|
|
|
|
if (cfqd->active_cic) {
|
|
put_io_context(cfqd->active_cic->ioc);
|
|
cfqd->active_cic = NULL;
|
|
}
|
|
|
|
cfqd->dispatch_slice = 0;
|
|
}
|
|
|
|
static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted)
|
|
{
|
|
struct cfq_queue *cfqq = cfqd->active_queue;
|
|
|
|
if (cfqq) {
|
|
/*
|
|
* use deferred expiry, if there are requests in progress as
|
|
* not to disturb the slice of the next queue
|
|
*/
|
|
if (cfq_cfqq_dispatched(cfqq))
|
|
cfq_mark_cfqq_expired(cfqq);
|
|
else
|
|
__cfq_slice_expired(cfqd, cfqq, preempted);
|
|
}
|
|
}
|
|
|
|
static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
|
|
{
|
|
WARN_ON(!RB_EMPTY(&cfqq->sort_list));
|
|
WARN_ON(cfqq != cfqd->active_queue);
|
|
|
|
/*
|
|
* idle is disabled, either manually or by past process history
|
|
*/
|
|
if (!cfqd->cfq_slice_idle)
|
|
return 0;
|
|
if (!cfq_cfqq_idle_window(cfqq))
|
|
return 0;
|
|
/*
|
|
* task has exited, don't wait
|
|
*/
|
|
if (cfqd->active_cic && !cfqd->active_cic->ioc->task)
|
|
return 0;
|
|
|
|
cfq_mark_cfqq_must_dispatch(cfqq);
|
|
cfq_mark_cfqq_wait_request(cfqq);
|
|
|
|
if (!timer_pending(&cfqd->idle_slice_timer)) {
|
|
unsigned long slice_left = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle);
|
|
|
|
cfqd->idle_slice_timer.expires = jiffies + slice_left;
|
|
add_timer(&cfqd->idle_slice_timer);
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq = crq->cfq_queue;
|
|
|
|
cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq);
|
|
cfq_remove_request(crq->request);
|
|
cfqq->on_dispatch[cfq_crq_is_sync(crq)]++;
|
|
elv_dispatch_sort(q, crq->request);
|
|
}
|
|
|
|
/*
|
|
* return expired entry, or NULL to just start from scratch in rbtree
|
|
*/
|
|
static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq)
|
|
{
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
struct request *rq;
|
|
struct cfq_rq *crq;
|
|
|
|
if (cfq_cfqq_fifo_expire(cfqq))
|
|
return NULL;
|
|
|
|
if (!list_empty(&cfqq->fifo)) {
|
|
int fifo = cfq_cfqq_class_sync(cfqq);
|
|
|
|
crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next));
|
|
rq = crq->request;
|
|
if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) {
|
|
cfq_mark_cfqq_fifo_expire(cfqq);
|
|
return crq;
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Scale schedule slice based on io priority. Use the sync time slice only
|
|
* if a queue is marked sync and has sync io queued. A sync queue with async
|
|
* io only, should not get full sync slice length.
|
|
*/
|
|
static inline int
|
|
cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)];
|
|
|
|
WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
|
|
|
|
return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio));
|
|
}
|
|
|
|
static inline void
|
|
cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
|
|
}
|
|
|
|
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));
|
|
}
|
|
|
|
/*
|
|
* get next queue for service
|
|
*/
|
|
static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
|
|
{
|
|
unsigned long now = jiffies;
|
|
struct cfq_queue *cfqq;
|
|
|
|
cfqq = cfqd->active_queue;
|
|
if (!cfqq)
|
|
goto new_queue;
|
|
|
|
if (cfq_cfqq_expired(cfqq))
|
|
goto new_queue;
|
|
|
|
/*
|
|
* slice has expired
|
|
*/
|
|
if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end))
|
|
goto expire;
|
|
|
|
/*
|
|
* if queue has requests, dispatch one. if not, check if
|
|
* enough slice is left to wait for one
|
|
*/
|
|
if (!RB_EMPTY(&cfqq->sort_list))
|
|
goto keep_queue;
|
|
else if (cfq_cfqq_class_sync(cfqq) &&
|
|
time_before(now, cfqq->slice_end)) {
|
|
if (cfq_arm_slice_timer(cfqd, cfqq))
|
|
return NULL;
|
|
}
|
|
|
|
expire:
|
|
cfq_slice_expired(cfqd, 0);
|
|
new_queue:
|
|
cfqq = cfq_set_active_queue(cfqd);
|
|
keep_queue:
|
|
return cfqq;
|
|
}
|
|
|
|
static int
|
|
__cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
int max_dispatch)
|
|
{
|
|
int dispatched = 0;
|
|
|
|
BUG_ON(RB_EMPTY(&cfqq->sort_list));
|
|
|
|
do {
|
|
struct cfq_rq *crq;
|
|
|
|
/*
|
|
* follow expired path, else get first next available
|
|
*/
|
|
if ((crq = cfq_check_fifo(cfqq)) == NULL)
|
|
crq = cfqq->next_crq;
|
|
|
|
/*
|
|
* finally, insert request into driver dispatch list
|
|
*/
|
|
cfq_dispatch_insert(cfqd->queue, crq);
|
|
|
|
cfqd->dispatch_slice++;
|
|
dispatched++;
|
|
|
|
if (!cfqd->active_cic) {
|
|
atomic_inc(&crq->io_context->ioc->refcount);
|
|
cfqd->active_cic = crq->io_context;
|
|
}
|
|
|
|
if (RB_EMPTY(&cfqq->sort_list))
|
|
break;
|
|
|
|
} while (dispatched < max_dispatch);
|
|
|
|
/*
|
|
* if slice end isn't set yet, set it. if at least one request was
|
|
* sync, use the sync time slice value
|
|
*/
|
|
if (!cfqq->slice_end)
|
|
cfq_set_prio_slice(cfqd, cfqq);
|
|
|
|
/*
|
|
* expire an async queue immediately if it has used up its slice. idle
|
|
* queue always expire after 1 dispatch round.
|
|
*/
|
|
if ((!cfq_cfqq_sync(cfqq) &&
|
|
cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
|
|
cfq_class_idle(cfqq))
|
|
cfq_slice_expired(cfqd, 0);
|
|
|
|
return dispatched;
|
|
}
|
|
|
|
static int
|
|
cfq_forced_dispatch_cfqqs(struct list_head *list)
|
|
{
|
|
int dispatched = 0;
|
|
struct cfq_queue *cfqq, *next;
|
|
struct cfq_rq *crq;
|
|
|
|
list_for_each_entry_safe(cfqq, next, list, cfq_list) {
|
|
while ((crq = cfqq->next_crq)) {
|
|
cfq_dispatch_insert(cfqq->cfqd->queue, crq);
|
|
dispatched++;
|
|
}
|
|
BUG_ON(!list_empty(&cfqq->fifo));
|
|
}
|
|
return dispatched;
|
|
}
|
|
|
|
static int
|
|
cfq_forced_dispatch(struct cfq_data *cfqd)
|
|
{
|
|
int i, dispatched = 0;
|
|
|
|
for (i = 0; i < CFQ_PRIO_LISTS; i++)
|
|
dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]);
|
|
|
|
dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr);
|
|
dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr);
|
|
dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr);
|
|
|
|
cfq_slice_expired(cfqd, 0);
|
|
|
|
BUG_ON(cfqd->busy_queues);
|
|
|
|
return dispatched;
|
|
}
|
|
|
|
static int
|
|
cfq_dispatch_requests(request_queue_t *q, int force)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_queue *cfqq;
|
|
|
|
if (!cfqd->busy_queues)
|
|
return 0;
|
|
|
|
if (unlikely(force))
|
|
return cfq_forced_dispatch(cfqd);
|
|
|
|
cfqq = cfq_select_queue(cfqd);
|
|
if (cfqq) {
|
|
int max_dispatch;
|
|
|
|
/*
|
|
* if idle window is disabled, allow queue buildup
|
|
*/
|
|
if (!cfq_cfqq_idle_window(cfqq) &&
|
|
cfqd->rq_in_driver >= cfqd->cfq_max_depth)
|
|
return 0;
|
|
|
|
cfq_clear_cfqq_must_dispatch(cfqq);
|
|
cfq_clear_cfqq_wait_request(cfqq);
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
|
|
max_dispatch = cfqd->cfq_quantum;
|
|
if (cfq_class_idle(cfqq))
|
|
max_dispatch = 1;
|
|
|
|
return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* task holds one reference to the queue, dropped when task exits. each crq
|
|
* in-flight on this queue also holds a reference, dropped when crq 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;
|
|
|
|
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);
|
|
}
|
|
|
|
cfq_put_cfqd(cfqq->cfqd);
|
|
|
|
/*
|
|
* it's on the empty list and still hashed
|
|
*/
|
|
list_del(&cfqq->cfq_list);
|
|
hlist_del(&cfqq->cfq_hash);
|
|
kmem_cache_free(cfq_pool, cfqq);
|
|
}
|
|
|
|
static inline struct cfq_queue *
|
|
__cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio,
|
|
const int hashval)
|
|
{
|
|
struct hlist_head *hash_list = &cfqd->cfq_hash[hashval];
|
|
struct hlist_node *entry, *next;
|
|
|
|
hlist_for_each_safe(entry, next, hash_list) {
|
|
struct cfq_queue *__cfqq = list_entry_qhash(entry);
|
|
const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->ioprio_class, __cfqq->ioprio);
|
|
|
|
if (__cfqq->key == key && (__p == prio || prio == CFQ_KEY_ANY))
|
|
return __cfqq;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio)
|
|
{
|
|
return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT));
|
|
}
|
|
|
|
static void cfq_free_io_context(struct cfq_io_context *cic)
|
|
{
|
|
struct cfq_io_context *__cic;
|
|
struct list_head *entry, *next;
|
|
|
|
list_for_each_safe(entry, next, &cic->list) {
|
|
__cic = list_entry(entry, struct cfq_io_context, list);
|
|
kmem_cache_free(cfq_ioc_pool, __cic);
|
|
}
|
|
|
|
kmem_cache_free(cfq_ioc_pool, cic);
|
|
}
|
|
|
|
/*
|
|
* Called with interrupts disabled
|
|
*/
|
|
static void cfq_exit_single_io_context(struct cfq_io_context *cic)
|
|
{
|
|
struct cfq_data *cfqd = cic->cfqq->cfqd;
|
|
request_queue_t *q = cfqd->queue;
|
|
|
|
WARN_ON(!irqs_disabled());
|
|
|
|
spin_lock(q->queue_lock);
|
|
|
|
if (unlikely(cic->cfqq == cfqd->active_queue)) {
|
|
__cfq_slice_expired(cfqd, cic->cfqq, 0);
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
|
|
cfq_put_queue(cic->cfqq);
|
|
cic->cfqq = NULL;
|
|
spin_unlock(q->queue_lock);
|
|
}
|
|
|
|
/*
|
|
* Another task may update the task cic list, if it is doing a queue lookup
|
|
* on its behalf. cfq_cic_lock excludes such concurrent updates
|
|
*/
|
|
static void cfq_exit_io_context(struct cfq_io_context *cic)
|
|
{
|
|
struct cfq_io_context *__cic;
|
|
struct list_head *entry;
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
|
|
/*
|
|
* put the reference this task is holding to the various queues
|
|
*/
|
|
list_for_each(entry, &cic->list) {
|
|
__cic = list_entry(entry, struct cfq_io_context, list);
|
|
cfq_exit_single_io_context(__cic);
|
|
}
|
|
|
|
cfq_exit_single_io_context(cic);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
static struct cfq_io_context *
|
|
cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
|
|
{
|
|
struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask);
|
|
|
|
if (cic) {
|
|
INIT_LIST_HEAD(&cic->list);
|
|
cic->cfqq = NULL;
|
|
cic->key = NULL;
|
|
cic->last_end_request = jiffies;
|
|
cic->ttime_total = 0;
|
|
cic->ttime_samples = 0;
|
|
cic->ttime_mean = 0;
|
|
cic->dtor = cfq_free_io_context;
|
|
cic->exit = cfq_exit_io_context;
|
|
}
|
|
|
|
return cic;
|
|
}
|
|
|
|
static void cfq_init_prio_data(struct cfq_queue *cfqq)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
int ioprio_class;
|
|
|
|
if (!cfq_cfqq_prio_changed(cfqq))
|
|
return;
|
|
|
|
ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio);
|
|
switch (ioprio_class) {
|
|
default:
|
|
printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
|
|
case IOPRIO_CLASS_NONE:
|
|
/*
|
|
* no prio set, place us in the middle of the BE classes
|
|
*/
|
|
cfqq->ioprio = task_nice_ioprio(tsk);
|
|
cfqq->ioprio_class = IOPRIO_CLASS_BE;
|
|
break;
|
|
case IOPRIO_CLASS_RT:
|
|
cfqq->ioprio = task_ioprio(tsk);
|
|
cfqq->ioprio_class = IOPRIO_CLASS_RT;
|
|
break;
|
|
case IOPRIO_CLASS_BE:
|
|
cfqq->ioprio = task_ioprio(tsk);
|
|
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;
|
|
|
|
if (cfq_cfqq_on_rr(cfqq))
|
|
cfq_resort_rr_list(cfqq, 0);
|
|
|
|
cfq_clear_cfqq_prio_changed(cfqq);
|
|
}
|
|
|
|
static inline void changed_ioprio(struct cfq_queue *cfqq)
|
|
{
|
|
if (cfqq) {
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
|
|
spin_lock(cfqd->queue->queue_lock);
|
|
cfq_mark_cfqq_prio_changed(cfqq);
|
|
cfq_init_prio_data(cfqq);
|
|
spin_unlock(cfqd->queue->queue_lock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* callback from sys_ioprio_set, irqs are disabled
|
|
*/
|
|
static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio)
|
|
{
|
|
struct cfq_io_context *cic = ioc->cic;
|
|
|
|
changed_ioprio(cic->cfqq);
|
|
|
|
list_for_each_entry(cic, &cic->list, list)
|
|
changed_ioprio(cic->cfqq);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct cfq_queue *
|
|
cfq_get_queue(struct cfq_data *cfqd, unsigned int key, unsigned short ioprio,
|
|
gfp_t gfp_mask)
|
|
{
|
|
const int hashval = hash_long(key, CFQ_QHASH_SHIFT);
|
|
struct cfq_queue *cfqq, *new_cfqq = NULL;
|
|
|
|
retry:
|
|
cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval);
|
|
|
|
if (!cfqq) {
|
|
if (new_cfqq) {
|
|
cfqq = new_cfqq;
|
|
new_cfqq = NULL;
|
|
} else if (gfp_mask & __GFP_WAIT) {
|
|
spin_unlock_irq(cfqd->queue->queue_lock);
|
|
new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
|
|
spin_lock_irq(cfqd->queue->queue_lock);
|
|
goto retry;
|
|
} else {
|
|
cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
|
|
if (!cfqq)
|
|
goto out;
|
|
}
|
|
|
|
memset(cfqq, 0, sizeof(*cfqq));
|
|
|
|
INIT_HLIST_NODE(&cfqq->cfq_hash);
|
|
INIT_LIST_HEAD(&cfqq->cfq_list);
|
|
RB_CLEAR_ROOT(&cfqq->sort_list);
|
|
INIT_LIST_HEAD(&cfqq->fifo);
|
|
|
|
cfqq->key = key;
|
|
hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
|
|
atomic_set(&cfqq->ref, 0);
|
|
cfqq->cfqd = cfqd;
|
|
atomic_inc(&cfqd->ref);
|
|
cfqq->service_last = 0;
|
|
/*
|
|
* set ->slice_left to allow preemption for a new process
|
|
*/
|
|
cfqq->slice_left = 2 * cfqd->cfq_slice_idle;
|
|
cfq_mark_cfqq_idle_window(cfqq);
|
|
cfq_mark_cfqq_prio_changed(cfqq);
|
|
cfq_init_prio_data(cfqq);
|
|
}
|
|
|
|
if (new_cfqq)
|
|
kmem_cache_free(cfq_pool, new_cfqq);
|
|
|
|
atomic_inc(&cfqq->ref);
|
|
out:
|
|
WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
|
|
return cfqq;
|
|
}
|
|
|
|
/*
|
|
* 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. Note that caller is holding a reference to
|
|
* cfqq, so we don't need to worry about it disappearing
|
|
*/
|
|
static struct cfq_io_context *
|
|
cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, 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);
|
|
if (!ioc)
|
|
return NULL;
|
|
|
|
if ((cic = ioc->cic) == NULL) {
|
|
cic = cfq_alloc_io_context(cfqd, gfp_mask);
|
|
|
|
if (cic == NULL)
|
|
goto err;
|
|
|
|
/*
|
|
* manually increment generic io_context usage count, it
|
|
* cannot go away since we are already holding one ref to it
|
|
*/
|
|
ioc->cic = cic;
|
|
ioc->set_ioprio = cfq_ioc_set_ioprio;
|
|
cic->ioc = ioc;
|
|
cic->key = cfqd;
|
|
atomic_inc(&cfqd->ref);
|
|
} else {
|
|
struct cfq_io_context *__cic;
|
|
|
|
/*
|
|
* the first cic on the list is actually the head itself
|
|
*/
|
|
if (cic->key == cfqd)
|
|
goto out;
|
|
|
|
/*
|
|
* cic exists, check if we already are there. linear search
|
|
* should be ok here, the list will usually not be more than
|
|
* 1 or a few entries long
|
|
*/
|
|
list_for_each_entry(__cic, &cic->list, list) {
|
|
/*
|
|
* this process is already holding a reference to
|
|
* this queue, so no need to get one more
|
|
*/
|
|
if (__cic->key == cfqd) {
|
|
cic = __cic;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* nope, process doesn't have a cic assoicated with this
|
|
* cfqq yet. get a new one and add to list
|
|
*/
|
|
__cic = cfq_alloc_io_context(cfqd, gfp_mask);
|
|
if (__cic == NULL)
|
|
goto err;
|
|
|
|
__cic->ioc = ioc;
|
|
__cic->key = cfqd;
|
|
atomic_inc(&cfqd->ref);
|
|
list_add(&__cic->list, &cic->list);
|
|
cic = __cic;
|
|
}
|
|
|
|
out:
|
|
return 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, ttime;
|
|
|
|
/*
|
|
* if this context already has stuff queued, thinktime is from
|
|
* last queue not last end
|
|
*/
|
|
#if 0
|
|
if (time_after(cic->last_end_request, cic->last_queue))
|
|
elapsed = jiffies - cic->last_end_request;
|
|
else
|
|
elapsed = jiffies - cic->last_queue;
|
|
#else
|
|
elapsed = jiffies - cic->last_end_request;
|
|
#endif
|
|
|
|
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;
|
|
}
|
|
|
|
#define sample_valid(samples) ((samples) > 80)
|
|
|
|
/*
|
|
* 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 enable_idle = cfq_cfqq_idle_window(cfqq);
|
|
|
|
if (!cic->ioc->task || !cfqd->cfq_slice_idle)
|
|
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 (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 cfq_rq *crq)
|
|
{
|
|
struct cfq_queue *cfqq = cfqd->active_queue;
|
|
|
|
if (cfq_class_idle(new_cfqq))
|
|
return 0;
|
|
|
|
if (!cfqq)
|
|
return 1;
|
|
|
|
if (cfq_class_idle(cfqq))
|
|
return 1;
|
|
if (!cfq_cfqq_wait_request(new_cfqq))
|
|
return 0;
|
|
/*
|
|
* if it doesn't have slice left, forget it
|
|
*/
|
|
if (new_cfqq->slice_left < cfqd->cfq_slice_idle)
|
|
return 0;
|
|
if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq))
|
|
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)
|
|
{
|
|
struct cfq_queue *__cfqq, *next;
|
|
|
|
list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list)
|
|
cfq_resort_rr_list(__cfqq, 1);
|
|
|
|
if (!cfqq->slice_left)
|
|
cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2;
|
|
|
|
cfqq->slice_end = cfqq->slice_left + jiffies;
|
|
__cfq_slice_expired(cfqd, cfqq, 1);
|
|
__cfq_set_active_queue(cfqd, cfqq);
|
|
}
|
|
|
|
/*
|
|
* should really be a ll_rw_blk.c helper
|
|
*/
|
|
static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq)
|
|
{
|
|
request_queue_t *q = cfqd->queue;
|
|
|
|
if (!blk_queue_plugged(q))
|
|
q->request_fn(q);
|
|
else
|
|
__generic_unplug_device(q);
|
|
}
|
|
|
|
/*
|
|
* Called when a new fs request (crq) is added (to cfqq). Check if there's
|
|
* something we should do about it
|
|
*/
|
|
static void
|
|
cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct cfq_rq *crq)
|
|
{
|
|
struct cfq_io_context *cic;
|
|
|
|
cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
|
|
|
|
/*
|
|
* we never wait for an async request and we don't allow preemption
|
|
* of an async request. so just return early
|
|
*/
|
|
if (!cfq_crq_is_sync(crq))
|
|
return;
|
|
|
|
cic = crq->io_context;
|
|
|
|
cfq_update_io_thinktime(cfqd, cic);
|
|
cfq_update_idle_window(cfqd, cfqq, cic);
|
|
|
|
cic->last_queue = jiffies;
|
|
|
|
if (cfqq == cfqd->active_queue) {
|
|
/*
|
|
* if we are waiting for a request for this queue, let it rip
|
|
* immediately and flag that we must not expire this queue
|
|
* just now
|
|
*/
|
|
if (cfq_cfqq_wait_request(cfqq)) {
|
|
cfq_mark_cfqq_must_dispatch(cfqq);
|
|
del_timer(&cfqd->idle_slice_timer);
|
|
cfq_start_queueing(cfqd, cfqq);
|
|
}
|
|
} else if (cfq_should_preempt(cfqd, cfqq, crq)) {
|
|
/*
|
|
* 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
|
|
*/
|
|
cfq_preempt_queue(cfqd, cfqq);
|
|
cfq_mark_cfqq_must_dispatch(cfqq);
|
|
cfq_start_queueing(cfqd, cfqq);
|
|
}
|
|
}
|
|
|
|
static void cfq_insert_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_rq *crq = RQ_DATA(rq);
|
|
struct cfq_queue *cfqq = crq->cfq_queue;
|
|
|
|
cfq_init_prio_data(cfqq);
|
|
|
|
cfq_add_crq_rb(crq);
|
|
|
|
list_add_tail(&rq->queuelist, &cfqq->fifo);
|
|
|
|
if (rq_mergeable(rq))
|
|
cfq_add_crq_hash(cfqd, crq);
|
|
|
|
cfq_crq_enqueued(cfqd, cfqq, crq);
|
|
}
|
|
|
|
static void cfq_completed_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct cfq_rq *crq = RQ_DATA(rq);
|
|
struct cfq_queue *cfqq = crq->cfq_queue;
|
|
struct cfq_data *cfqd = cfqq->cfqd;
|
|
const int sync = cfq_crq_is_sync(crq);
|
|
unsigned long now;
|
|
|
|
now = jiffies;
|
|
|
|
WARN_ON(!cfqd->rq_in_driver);
|
|
WARN_ON(!cfqq->on_dispatch[sync]);
|
|
cfqd->rq_in_driver--;
|
|
cfqq->on_dispatch[sync]--;
|
|
|
|
if (!cfq_class_idle(cfqq))
|
|
cfqd->last_end_request = now;
|
|
|
|
if (!cfq_cfqq_dispatched(cfqq)) {
|
|
if (cfq_cfqq_on_rr(cfqq)) {
|
|
cfqq->service_last = now;
|
|
cfq_resort_rr_list(cfqq, 0);
|
|
}
|
|
if (cfq_cfqq_expired(cfqq)) {
|
|
__cfq_slice_expired(cfqd, cfqq, 0);
|
|
cfq_schedule_dispatch(cfqd);
|
|
}
|
|
}
|
|
|
|
if (cfq_crq_is_sync(crq))
|
|
crq->io_context->last_end_request = now;
|
|
}
|
|
|
|
static struct request *
|
|
cfq_former_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct cfq_rq *crq = RQ_DATA(rq);
|
|
struct rb_node *rbprev = rb_prev(&crq->rb_node);
|
|
|
|
if (rbprev)
|
|
return rb_entry_crq(rbprev)->request;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct request *
|
|
cfq_latter_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct cfq_rq *crq = RQ_DATA(rq);
|
|
struct rb_node *rbnext = rb_next(&crq->rb_node);
|
|
|
|
if (rbnext)
|
|
return rb_entry_crq(rbnext)->request;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
const int ioprio_class = cfqq->ioprio_class;
|
|
const int ioprio = cfqq->ioprio;
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* refile between round-robin lists if we moved the priority class
|
|
*/
|
|
if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) &&
|
|
cfq_cfqq_on_rr(cfqq))
|
|
cfq_resort_rr_list(cfqq, 0);
|
|
}
|
|
|
|
static inline pid_t cfq_queue_pid(struct task_struct *task, int rw)
|
|
{
|
|
if (rw == READ || process_sync(task))
|
|
return task->pid;
|
|
|
|
return CFQ_KEY_ASYNC;
|
|
}
|
|
|
|
static inline int
|
|
__cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq,
|
|
struct task_struct *task, int rw)
|
|
{
|
|
#if 1
|
|
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;
|
|
#else
|
|
if (!cfqq || task->flags & PF_MEMALLOC)
|
|
return ELV_MQUEUE_MAY;
|
|
if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) {
|
|
if (cfq_cfqq_wait_request(cfqq))
|
|
return ELV_MQUEUE_MUST;
|
|
|
|
/*
|
|
* only allow 1 ELV_MQUEUE_MUST per slice, otherwise we
|
|
* can quickly flood the queue with writes from a single task
|
|
*/
|
|
if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) {
|
|
cfq_mark_cfqq_must_alloc_slice(cfqq);
|
|
return ELV_MQUEUE_MUST;
|
|
}
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
if (cfq_class_idle(cfqq))
|
|
return ELV_MQUEUE_NO;
|
|
if (cfqq->allocated[rw] >= cfqd->max_queued) {
|
|
struct io_context *ioc = get_io_context(GFP_ATOMIC);
|
|
int ret = ELV_MQUEUE_NO;
|
|
|
|
if (ioc && ioc->nr_batch_requests)
|
|
ret = ELV_MQUEUE_MAY;
|
|
|
|
put_io_context(ioc);
|
|
return ret;
|
|
}
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
#endif
|
|
}
|
|
|
|
static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct task_struct *tsk = current;
|
|
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
|
|
*/
|
|
cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio);
|
|
if (cfqq) {
|
|
cfq_init_prio_data(cfqq);
|
|
cfq_prio_boost(cfqq);
|
|
|
|
return __cfq_may_queue(cfqd, cfqq, tsk, rw);
|
|
}
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
|
|
static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct request_list *rl = &q->rq;
|
|
|
|
if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) {
|
|
smp_mb();
|
|
if (waitqueue_active(&rl->wait[READ]))
|
|
wake_up(&rl->wait[READ]);
|
|
}
|
|
|
|
if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) {
|
|
smp_mb();
|
|
if (waitqueue_active(&rl->wait[WRITE]))
|
|
wake_up(&rl->wait[WRITE]);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* queue lock held here
|
|
*/
|
|
static void cfq_put_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct cfq_rq *crq = RQ_DATA(rq);
|
|
|
|
if (crq) {
|
|
struct cfq_queue *cfqq = crq->cfq_queue;
|
|
const int rw = rq_data_dir(rq);
|
|
|
|
BUG_ON(!cfqq->allocated[rw]);
|
|
cfqq->allocated[rw]--;
|
|
|
|
put_io_context(crq->io_context->ioc);
|
|
|
|
mempool_free(crq, cfqd->crq_pool);
|
|
rq->elevator_private = NULL;
|
|
|
|
cfq_check_waiters(q, cfqq);
|
|
cfq_put_queue(cfqq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate cfq data structures associated with this request.
|
|
*/
|
|
static int
|
|
cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
|
|
gfp_t gfp_mask)
|
|
{
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
struct task_struct *tsk = current;
|
|
struct cfq_io_context *cic;
|
|
const int rw = rq_data_dir(rq);
|
|
pid_t key = cfq_queue_pid(tsk, rw);
|
|
struct cfq_queue *cfqq;
|
|
struct cfq_rq *crq;
|
|
unsigned long flags;
|
|
|
|
might_sleep_if(gfp_mask & __GFP_WAIT);
|
|
|
|
cic = cfq_get_io_context(cfqd, key, gfp_mask);
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
if (!cic)
|
|
goto queue_fail;
|
|
|
|
if (!cic->cfqq) {
|
|
cfqq = cfq_get_queue(cfqd, key, tsk->ioprio, gfp_mask);
|
|
if (!cfqq)
|
|
goto queue_fail;
|
|
|
|
cic->cfqq = cfqq;
|
|
} else
|
|
cfqq = cic->cfqq;
|
|
|
|
cfqq->allocated[rw]++;
|
|
cfq_clear_cfqq_must_alloc(cfqq);
|
|
cfqd->rq_starved = 0;
|
|
atomic_inc(&cfqq->ref);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
|
|
crq = mempool_alloc(cfqd->crq_pool, gfp_mask);
|
|
if (crq) {
|
|
RB_CLEAR(&crq->rb_node);
|
|
crq->rb_key = 0;
|
|
crq->request = rq;
|
|
INIT_HLIST_NODE(&crq->hash);
|
|
crq->cfq_queue = cfqq;
|
|
crq->io_context = cic;
|
|
|
|
if (rw == READ || process_sync(tsk))
|
|
cfq_mark_crq_is_sync(crq);
|
|
else
|
|
cfq_clear_crq_is_sync(crq);
|
|
|
|
rq->elevator_private = crq;
|
|
return 0;
|
|
}
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
cfqq->allocated[rw]--;
|
|
if (!(cfqq->allocated[0] + cfqq->allocated[1]))
|
|
cfq_mark_cfqq_must_alloc(cfqq);
|
|
cfq_put_queue(cfqq);
|
|
queue_fail:
|
|
if (cic)
|
|
put_io_context(cic->ioc);
|
|
/*
|
|
* mark us rq allocation starved. we need to kickstart the process
|
|
* ourselves if there are no pending requests that can do it for us.
|
|
* that would be an extremely rare OOM situation
|
|
*/
|
|
cfqd->rq_starved = 1;
|
|
cfq_schedule_dispatch(cfqd);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
return 1;
|
|
}
|
|
|
|
static void cfq_kick_queue(void *data)
|
|
{
|
|
request_queue_t *q = data;
|
|
struct cfq_data *cfqd = q->elevator->elevator_data;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
if (cfqd->rq_starved) {
|
|
struct request_list *rl = &q->rq;
|
|
|
|
/*
|
|
* we aren't guaranteed to get a request after this, but we
|
|
* have to be opportunistic
|
|
*/
|
|
smp_mb();
|
|
if (waitqueue_active(&rl->wait[READ]))
|
|
wake_up(&rl->wait[READ]);
|
|
if (waitqueue_active(&rl->wait[WRITE]))
|
|
wake_up(&rl->wait[WRITE]);
|
|
}
|
|
|
|
blk_remove_plug(q);
|
|
q->request_fn(q);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
|
|
if ((cfqq = cfqd->active_queue) != NULL) {
|
|
unsigned long now = jiffies;
|
|
|
|
/*
|
|
* expired
|
|
*/
|
|
if (time_after(now, cfqq->slice_end))
|
|
goto expire;
|
|
|
|
/*
|
|
* only expire and reinvoke request handler, if there are
|
|
* other queues with pending requests
|
|
*/
|
|
if (!cfqd->busy_queues) {
|
|
cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end);
|
|
add_timer(&cfqd->idle_slice_timer);
|
|
goto out_cont;
|
|
}
|
|
|
|
/*
|
|
* not expired and it has a request pending, let it dispatch
|
|
*/
|
|
if (!RB_EMPTY(&cfqq->sort_list)) {
|
|
cfq_mark_cfqq_must_dispatch(cfqq);
|
|
goto out_kick;
|
|
}
|
|
}
|
|
expire:
|
|
cfq_slice_expired(cfqd, 0);
|
|
out_kick:
|
|
cfq_schedule_dispatch(cfqd);
|
|
out_cont:
|
|
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
|
|
}
|
|
|
|
/*
|
|
* Timer running if an idle class queue is waiting for service
|
|
*/
|
|
static void cfq_idle_class_timer(unsigned long data)
|
|
{
|
|
struct cfq_data *cfqd = (struct cfq_data *) data;
|
|
unsigned long flags, end;
|
|
|
|
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
|
|
|
|
/*
|
|
* race with a non-idle queue, reset timer
|
|
*/
|
|
end = cfqd->last_end_request + CFQ_IDLE_GRACE;
|
|
if (!time_after_eq(jiffies, end)) {
|
|
cfqd->idle_class_timer.expires = end;
|
|
add_timer(&cfqd->idle_class_timer);
|
|
} else
|
|
cfq_schedule_dispatch(cfqd);
|
|
|
|
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);
|
|
del_timer_sync(&cfqd->idle_class_timer);
|
|
blk_sync_queue(cfqd->queue);
|
|
}
|
|
|
|
static void cfq_put_cfqd(struct cfq_data *cfqd)
|
|
{
|
|
request_queue_t *q = cfqd->queue;
|
|
|
|
if (!atomic_dec_and_test(&cfqd->ref))
|
|
return;
|
|
|
|
cfq_shutdown_timer_wq(cfqd);
|
|
blk_put_queue(q);
|
|
|
|
mempool_destroy(cfqd->crq_pool);
|
|
kfree(cfqd->crq_hash);
|
|
kfree(cfqd->cfq_hash);
|
|
kfree(cfqd);
|
|
}
|
|
|
|
static void cfq_exit_queue(elevator_t *e)
|
|
{
|
|
struct cfq_data *cfqd = e->elevator_data;
|
|
|
|
cfq_shutdown_timer_wq(cfqd);
|
|
cfq_put_cfqd(cfqd);
|
|
}
|
|
|
|
static int cfq_init_queue(request_queue_t *q, elevator_t *e)
|
|
{
|
|
struct cfq_data *cfqd;
|
|
int i;
|
|
|
|
cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL);
|
|
if (!cfqd)
|
|
return -ENOMEM;
|
|
|
|
memset(cfqd, 0, sizeof(*cfqd));
|
|
|
|
for (i = 0; i < CFQ_PRIO_LISTS; i++)
|
|
INIT_LIST_HEAD(&cfqd->rr_list[i]);
|
|
|
|
INIT_LIST_HEAD(&cfqd->busy_rr);
|
|
INIT_LIST_HEAD(&cfqd->cur_rr);
|
|
INIT_LIST_HEAD(&cfqd->idle_rr);
|
|
INIT_LIST_HEAD(&cfqd->empty_list);
|
|
|
|
cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL);
|
|
if (!cfqd->crq_hash)
|
|
goto out_crqhash;
|
|
|
|
cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL);
|
|
if (!cfqd->cfq_hash)
|
|
goto out_cfqhash;
|
|
|
|
cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool);
|
|
if (!cfqd->crq_pool)
|
|
goto out_crqpool;
|
|
|
|
for (i = 0; i < CFQ_MHASH_ENTRIES; i++)
|
|
INIT_HLIST_HEAD(&cfqd->crq_hash[i]);
|
|
for (i = 0; i < CFQ_QHASH_ENTRIES; i++)
|
|
INIT_HLIST_HEAD(&cfqd->cfq_hash[i]);
|
|
|
|
e->elevator_data = cfqd;
|
|
|
|
cfqd->queue = q;
|
|
atomic_inc(&q->refcnt);
|
|
|
|
cfqd->max_queued = q->nr_requests / 4;
|
|
q->nr_batching = cfq_queued;
|
|
|
|
init_timer(&cfqd->idle_slice_timer);
|
|
cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
|
|
cfqd->idle_slice_timer.data = (unsigned long) cfqd;
|
|
|
|
init_timer(&cfqd->idle_class_timer);
|
|
cfqd->idle_class_timer.function = cfq_idle_class_timer;
|
|
cfqd->idle_class_timer.data = (unsigned long) cfqd;
|
|
|
|
INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q);
|
|
|
|
atomic_set(&cfqd->ref, 1);
|
|
|
|
cfqd->cfq_queued = cfq_queued;
|
|
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->cfq_max_depth = cfq_max_depth;
|
|
|
|
return 0;
|
|
out_crqpool:
|
|
kfree(cfqd->cfq_hash);
|
|
out_cfqhash:
|
|
kfree(cfqd->crq_hash);
|
|
out_crqhash:
|
|
kfree(cfqd);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
static void cfq_slab_kill(void)
|
|
{
|
|
if (crq_pool)
|
|
kmem_cache_destroy(crq_pool);
|
|
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)
|
|
{
|
|
crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0,
|
|
NULL, NULL);
|
|
if (!crq_pool)
|
|
goto fail;
|
|
|
|
cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0,
|
|
NULL, NULL);
|
|
if (!cfq_pool)
|
|
goto fail;
|
|
|
|
cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool",
|
|
sizeof(struct cfq_io_context), 0, 0, NULL, NULL);
|
|
if (!cfq_ioc_pool)
|
|
goto fail;
|
|
|
|
return 0;
|
|
fail:
|
|
cfq_slab_kill();
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* sysfs parts below -->
|
|
*/
|
|
struct cfq_fs_entry {
|
|
struct attribute attr;
|
|
ssize_t (*show)(struct cfq_data *, char *);
|
|
ssize_t (*store)(struct cfq_data *, const char *, size_t);
|
|
};
|
|
|
|
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 cfq_data *cfqd, char *page) \
|
|
{ \
|
|
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_queued_show, cfqd->cfq_queued, 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_max_show, cfqd->cfq_back_max, 0);
|
|
SHOW_FUNCTION(cfq_back_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);
|
|
SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0);
|
|
#undef SHOW_FUNCTION
|
|
|
|
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
|
|
static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \
|
|
{ \
|
|
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_queued_store, &cfqd->cfq_queued, 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_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
|
|
STORE_FUNCTION(cfq_back_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);
|
|
STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 1, UINT_MAX, 0);
|
|
#undef STORE_FUNCTION
|
|
|
|
static struct cfq_fs_entry cfq_quantum_entry = {
|
|
.attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_quantum_show,
|
|
.store = cfq_quantum_store,
|
|
};
|
|
static struct cfq_fs_entry cfq_queued_entry = {
|
|
.attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_queued_show,
|
|
.store = cfq_queued_store,
|
|
};
|
|
static struct cfq_fs_entry cfq_fifo_expire_sync_entry = {
|
|
.attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_fifo_expire_sync_show,
|
|
.store = cfq_fifo_expire_sync_store,
|
|
};
|
|
static struct cfq_fs_entry cfq_fifo_expire_async_entry = {
|
|
.attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_fifo_expire_async_show,
|
|
.store = cfq_fifo_expire_async_store,
|
|
};
|
|
static struct cfq_fs_entry cfq_back_max_entry = {
|
|
.attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_back_max_show,
|
|
.store = cfq_back_max_store,
|
|
};
|
|
static struct cfq_fs_entry cfq_back_penalty_entry = {
|
|
.attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_back_penalty_show,
|
|
.store = cfq_back_penalty_store,
|
|
};
|
|
static struct cfq_fs_entry cfq_slice_sync_entry = {
|
|
.attr = {.name = "slice_sync", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_slice_sync_show,
|
|
.store = cfq_slice_sync_store,
|
|
};
|
|
static struct cfq_fs_entry cfq_slice_async_entry = {
|
|
.attr = {.name = "slice_async", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_slice_async_show,
|
|
.store = cfq_slice_async_store,
|
|
};
|
|
static struct cfq_fs_entry cfq_slice_async_rq_entry = {
|
|
.attr = {.name = "slice_async_rq", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_slice_async_rq_show,
|
|
.store = cfq_slice_async_rq_store,
|
|
};
|
|
static struct cfq_fs_entry cfq_slice_idle_entry = {
|
|
.attr = {.name = "slice_idle", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_slice_idle_show,
|
|
.store = cfq_slice_idle_store,
|
|
};
|
|
static struct cfq_fs_entry cfq_max_depth_entry = {
|
|
.attr = {.name = "max_depth", .mode = S_IRUGO | S_IWUSR },
|
|
.show = cfq_max_depth_show,
|
|
.store = cfq_max_depth_store,
|
|
};
|
|
|
|
static struct attribute *default_attrs[] = {
|
|
&cfq_quantum_entry.attr,
|
|
&cfq_queued_entry.attr,
|
|
&cfq_fifo_expire_sync_entry.attr,
|
|
&cfq_fifo_expire_async_entry.attr,
|
|
&cfq_back_max_entry.attr,
|
|
&cfq_back_penalty_entry.attr,
|
|
&cfq_slice_sync_entry.attr,
|
|
&cfq_slice_async_entry.attr,
|
|
&cfq_slice_async_rq_entry.attr,
|
|
&cfq_slice_idle_entry.attr,
|
|
&cfq_max_depth_entry.attr,
|
|
NULL,
|
|
};
|
|
|
|
#define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr)
|
|
|
|
static ssize_t
|
|
cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
|
|
{
|
|
elevator_t *e = container_of(kobj, elevator_t, kobj);
|
|
struct cfq_fs_entry *entry = to_cfq(attr);
|
|
|
|
if (!entry->show)
|
|
return -EIO;
|
|
|
|
return entry->show(e->elevator_data, page);
|
|
}
|
|
|
|
static ssize_t
|
|
cfq_attr_store(struct kobject *kobj, struct attribute *attr,
|
|
const char *page, size_t length)
|
|
{
|
|
elevator_t *e = container_of(kobj, elevator_t, kobj);
|
|
struct cfq_fs_entry *entry = to_cfq(attr);
|
|
|
|
if (!entry->store)
|
|
return -EIO;
|
|
|
|
return entry->store(e->elevator_data, page, length);
|
|
}
|
|
|
|
static struct sysfs_ops cfq_sysfs_ops = {
|
|
.show = cfq_attr_show,
|
|
.store = cfq_attr_store,
|
|
};
|
|
|
|
static struct kobj_type cfq_ktype = {
|
|
.sysfs_ops = &cfq_sysfs_ops,
|
|
.default_attrs = default_attrs,
|
|
};
|
|
|
|
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_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 = cfq_former_request,
|
|
.elevator_latter_req_fn = cfq_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,
|
|
},
|
|
.elevator_ktype = &cfq_ktype,
|
|
.elevator_name = "cfq",
|
|
.elevator_owner = THIS_MODULE,
|
|
};
|
|
|
|
static int __init cfq_init(void)
|
|
{
|
|
int ret;
|
|
|
|
/*
|
|
* 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;
|
|
|
|
ret = elv_register(&iosched_cfq);
|
|
if (ret)
|
|
cfq_slab_kill();
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void __exit cfq_exit(void)
|
|
{
|
|
elv_unregister(&iosched_cfq);
|
|
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");
|