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![Tejun Heo](/assets/img/avatar_default.png)
tg_stats_alloc_lock nests inside queue lock and should always be held with irq disabled. throtl_pd_{init|exit}() were using non-irqsafe spinlock ops which triggered inverse lock ordering via irq warning via RCU freeing of blkg invoking throtl_pd_exit() w/o disabling IRQ. Update both functions to use irq safe operations. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sasha Levin <sasha.levin@oracle.com> LKML-Reference: <1335339396.16988.80.camel@lappy> Signed-off-by: Jens Axboe <axboe@kernel.dk>
1283 lines
31 KiB
C
1283 lines
31 KiB
C
/*
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* Interface for controlling IO bandwidth on a request queue
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*
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* Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com>
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/blkdev.h>
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#include <linux/bio.h>
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#include <linux/blktrace_api.h>
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#include "blk-cgroup.h"
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#include "blk.h"
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/* Max dispatch from a group in 1 round */
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static int throtl_grp_quantum = 8;
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/* Total max dispatch from all groups in one round */
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static int throtl_quantum = 32;
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/* Throttling is performed over 100ms slice and after that slice is renewed */
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static unsigned long throtl_slice = HZ/10; /* 100 ms */
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static struct blkcg_policy blkcg_policy_throtl;
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/* A workqueue to queue throttle related work */
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static struct workqueue_struct *kthrotld_workqueue;
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static void throtl_schedule_delayed_work(struct throtl_data *td,
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unsigned long delay);
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struct throtl_rb_root {
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struct rb_root rb;
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struct rb_node *left;
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unsigned int count;
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unsigned long min_disptime;
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};
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#define THROTL_RB_ROOT (struct throtl_rb_root) { .rb = RB_ROOT, .left = NULL, \
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.count = 0, .min_disptime = 0}
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#define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
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/* Per-cpu group stats */
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struct tg_stats_cpu {
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/* total bytes transferred */
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struct blkg_rwstat service_bytes;
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/* total IOs serviced, post merge */
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struct blkg_rwstat serviced;
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};
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struct throtl_grp {
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/* must be the first member */
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struct blkg_policy_data pd;
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/* active throtl group service_tree member */
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struct rb_node rb_node;
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/*
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* Dispatch time in jiffies. This is the estimated time when group
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* will unthrottle and is ready to dispatch more bio. It is used as
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* key to sort active groups in service tree.
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*/
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unsigned long disptime;
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unsigned int flags;
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/* Two lists for READ and WRITE */
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struct bio_list bio_lists[2];
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/* Number of queued bios on READ and WRITE lists */
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unsigned int nr_queued[2];
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/* bytes per second rate limits */
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uint64_t bps[2];
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/* IOPS limits */
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unsigned int iops[2];
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/* Number of bytes disptached in current slice */
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uint64_t bytes_disp[2];
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/* Number of bio's dispatched in current slice */
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unsigned int io_disp[2];
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/* When did we start a new slice */
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unsigned long slice_start[2];
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unsigned long slice_end[2];
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/* Some throttle limits got updated for the group */
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int limits_changed;
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/* Per cpu stats pointer */
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struct tg_stats_cpu __percpu *stats_cpu;
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/* List of tgs waiting for per cpu stats memory to be allocated */
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struct list_head stats_alloc_node;
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};
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struct throtl_data
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{
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/* service tree for active throtl groups */
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struct throtl_rb_root tg_service_tree;
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struct request_queue *queue;
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/* Total Number of queued bios on READ and WRITE lists */
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unsigned int nr_queued[2];
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/*
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* number of total undestroyed groups
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*/
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unsigned int nr_undestroyed_grps;
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/* Work for dispatching throttled bios */
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struct delayed_work throtl_work;
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int limits_changed;
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};
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/* list and work item to allocate percpu group stats */
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static DEFINE_SPINLOCK(tg_stats_alloc_lock);
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static LIST_HEAD(tg_stats_alloc_list);
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static void tg_stats_alloc_fn(struct work_struct *);
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static DECLARE_DELAYED_WORK(tg_stats_alloc_work, tg_stats_alloc_fn);
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static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd)
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{
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return pd ? container_of(pd, struct throtl_grp, pd) : NULL;
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}
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static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg)
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{
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return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl));
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}
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static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg)
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{
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return pd_to_blkg(&tg->pd);
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}
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static inline struct throtl_grp *td_root_tg(struct throtl_data *td)
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{
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return blkg_to_tg(td->queue->root_blkg);
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}
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enum tg_state_flags {
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THROTL_TG_FLAG_on_rr = 0, /* on round-robin busy list */
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};
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#define THROTL_TG_FNS(name) \
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static inline void throtl_mark_tg_##name(struct throtl_grp *tg) \
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{ \
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(tg)->flags |= (1 << THROTL_TG_FLAG_##name); \
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} \
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static inline void throtl_clear_tg_##name(struct throtl_grp *tg) \
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{ \
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(tg)->flags &= ~(1 << THROTL_TG_FLAG_##name); \
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} \
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static inline int throtl_tg_##name(const struct throtl_grp *tg) \
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{ \
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return ((tg)->flags & (1 << THROTL_TG_FLAG_##name)) != 0; \
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}
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THROTL_TG_FNS(on_rr);
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#define throtl_log_tg(td, tg, fmt, args...) do { \
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char __pbuf[128]; \
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\
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blkg_path(tg_to_blkg(tg), __pbuf, sizeof(__pbuf)); \
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blk_add_trace_msg((td)->queue, "throtl %s " fmt, __pbuf, ##args); \
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} while (0)
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#define throtl_log(td, fmt, args...) \
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blk_add_trace_msg((td)->queue, "throtl " fmt, ##args)
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static inline unsigned int total_nr_queued(struct throtl_data *td)
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{
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return td->nr_queued[0] + td->nr_queued[1];
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}
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/*
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* Worker for allocating per cpu stat for tgs. This is scheduled on the
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* system_nrt_wq once there are some groups on the alloc_list waiting for
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* allocation.
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*/
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static void tg_stats_alloc_fn(struct work_struct *work)
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{
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static struct tg_stats_cpu *stats_cpu; /* this fn is non-reentrant */
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struct delayed_work *dwork = to_delayed_work(work);
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bool empty = false;
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alloc_stats:
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if (!stats_cpu) {
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stats_cpu = alloc_percpu(struct tg_stats_cpu);
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if (!stats_cpu) {
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/* allocation failed, try again after some time */
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queue_delayed_work(system_nrt_wq, dwork,
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msecs_to_jiffies(10));
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return;
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}
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}
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spin_lock_irq(&tg_stats_alloc_lock);
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if (!list_empty(&tg_stats_alloc_list)) {
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struct throtl_grp *tg = list_first_entry(&tg_stats_alloc_list,
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struct throtl_grp,
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stats_alloc_node);
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swap(tg->stats_cpu, stats_cpu);
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list_del_init(&tg->stats_alloc_node);
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}
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empty = list_empty(&tg_stats_alloc_list);
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spin_unlock_irq(&tg_stats_alloc_lock);
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if (!empty)
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goto alloc_stats;
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}
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static void throtl_pd_init(struct blkcg_gq *blkg)
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{
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struct throtl_grp *tg = blkg_to_tg(blkg);
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unsigned long flags;
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RB_CLEAR_NODE(&tg->rb_node);
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bio_list_init(&tg->bio_lists[0]);
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bio_list_init(&tg->bio_lists[1]);
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tg->limits_changed = false;
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tg->bps[READ] = -1;
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tg->bps[WRITE] = -1;
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tg->iops[READ] = -1;
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tg->iops[WRITE] = -1;
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/*
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* Ugh... We need to perform per-cpu allocation for tg->stats_cpu
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* but percpu allocator can't be called from IO path. Queue tg on
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* tg_stats_alloc_list and allocate from work item.
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*/
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spin_lock_irqsave(&tg_stats_alloc_lock, flags);
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list_add(&tg->stats_alloc_node, &tg_stats_alloc_list);
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queue_delayed_work(system_nrt_wq, &tg_stats_alloc_work, 0);
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spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
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}
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static void throtl_pd_exit(struct blkcg_gq *blkg)
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{
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struct throtl_grp *tg = blkg_to_tg(blkg);
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unsigned long flags;
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spin_lock_irqsave(&tg_stats_alloc_lock, flags);
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list_del_init(&tg->stats_alloc_node);
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spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
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free_percpu(tg->stats_cpu);
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}
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static void throtl_pd_reset_stats(struct blkcg_gq *blkg)
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{
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struct throtl_grp *tg = blkg_to_tg(blkg);
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int cpu;
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if (tg->stats_cpu == NULL)
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return;
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for_each_possible_cpu(cpu) {
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struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
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blkg_rwstat_reset(&sc->service_bytes);
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blkg_rwstat_reset(&sc->serviced);
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}
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}
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static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td,
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struct blkcg *blkcg)
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{
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/*
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* This is the common case when there are no blkcgs. Avoid lookup
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* in this case
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*/
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if (blkcg == &blkcg_root)
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return td_root_tg(td);
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return blkg_to_tg(blkg_lookup(blkcg, td->queue));
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}
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static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
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struct blkcg *blkcg)
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{
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struct request_queue *q = td->queue;
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struct throtl_grp *tg = NULL;
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/*
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* This is the common case when there are no blkcgs. Avoid lookup
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* in this case
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*/
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if (blkcg == &blkcg_root) {
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tg = td_root_tg(td);
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} else {
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struct blkcg_gq *blkg;
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blkg = blkg_lookup_create(blkcg, q);
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/* if %NULL and @q is alive, fall back to root_tg */
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if (!IS_ERR(blkg))
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tg = blkg_to_tg(blkg);
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else if (!blk_queue_dead(q))
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tg = td_root_tg(td);
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}
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return tg;
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}
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static struct throtl_grp *throtl_rb_first(struct throtl_rb_root *root)
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{
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/* Service tree is empty */
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if (!root->count)
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return NULL;
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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_tg(root->left);
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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 throtl_rb_erase(struct rb_node *n, struct throtl_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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--root->count;
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}
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static void update_min_dispatch_time(struct throtl_rb_root *st)
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{
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struct throtl_grp *tg;
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tg = throtl_rb_first(st);
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if (!tg)
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return;
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st->min_disptime = tg->disptime;
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}
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static void
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tg_service_tree_add(struct throtl_rb_root *st, struct throtl_grp *tg)
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{
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struct rb_node **node = &st->rb.rb_node;
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struct rb_node *parent = NULL;
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struct throtl_grp *__tg;
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unsigned long key = tg->disptime;
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int left = 1;
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while (*node != NULL) {
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parent = *node;
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__tg = rb_entry_tg(parent);
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if (time_before(key, __tg->disptime))
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node = &parent->rb_left;
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else {
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node = &parent->rb_right;
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left = 0;
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}
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}
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if (left)
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st->left = &tg->rb_node;
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rb_link_node(&tg->rb_node, parent, node);
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rb_insert_color(&tg->rb_node, &st->rb);
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}
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static void __throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
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{
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struct throtl_rb_root *st = &td->tg_service_tree;
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tg_service_tree_add(st, tg);
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throtl_mark_tg_on_rr(tg);
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st->count++;
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}
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static void throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
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{
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if (!throtl_tg_on_rr(tg))
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__throtl_enqueue_tg(td, tg);
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}
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static void __throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
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{
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throtl_rb_erase(&tg->rb_node, &td->tg_service_tree);
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throtl_clear_tg_on_rr(tg);
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}
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static void throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
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{
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if (throtl_tg_on_rr(tg))
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__throtl_dequeue_tg(td, tg);
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}
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static void throtl_schedule_next_dispatch(struct throtl_data *td)
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{
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struct throtl_rb_root *st = &td->tg_service_tree;
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/*
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* If there are more bios pending, schedule more work.
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*/
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if (!total_nr_queued(td))
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return;
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BUG_ON(!st->count);
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update_min_dispatch_time(st);
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if (time_before_eq(st->min_disptime, jiffies))
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throtl_schedule_delayed_work(td, 0);
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else
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throtl_schedule_delayed_work(td, (st->min_disptime - jiffies));
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}
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static inline void
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throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
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{
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tg->bytes_disp[rw] = 0;
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tg->io_disp[rw] = 0;
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tg->slice_start[rw] = jiffies;
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tg->slice_end[rw] = jiffies + throtl_slice;
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throtl_log_tg(td, tg, "[%c] new slice start=%lu end=%lu jiffies=%lu",
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rw == READ ? 'R' : 'W', tg->slice_start[rw],
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tg->slice_end[rw], jiffies);
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}
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static inline void throtl_set_slice_end(struct throtl_data *td,
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struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
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{
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tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
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}
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static inline void throtl_extend_slice(struct throtl_data *td,
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struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
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{
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tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
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throtl_log_tg(td, tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu",
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rw == READ ? 'R' : 'W', tg->slice_start[rw],
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tg->slice_end[rw], jiffies);
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}
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/* Determine if previously allocated or extended slice is complete or not */
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static bool
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throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw)
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{
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if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))
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return 0;
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return 1;
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}
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/* Trim the used slices and adjust slice start accordingly */
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static inline void
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throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
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{
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unsigned long nr_slices, time_elapsed, io_trim;
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u64 bytes_trim, tmp;
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BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
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/*
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* If bps are unlimited (-1), then time slice don't get
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* renewed. Don't try to trim the slice if slice is used. A new
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* slice will start when appropriate.
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*/
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if (throtl_slice_used(td, tg, rw))
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return;
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/*
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* A bio has been dispatched. Also adjust slice_end. It might happen
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* that initially cgroup limit was very low resulting in high
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* slice_end, but later limit was bumped up and bio was dispached
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* sooner, then we need to reduce slice_end. A high bogus slice_end
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* is bad because it does not allow new slice to start.
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*/
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throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice);
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|
time_elapsed = jiffies - tg->slice_start[rw];
|
|
|
|
nr_slices = time_elapsed / throtl_slice;
|
|
|
|
if (!nr_slices)
|
|
return;
|
|
tmp = tg->bps[rw] * throtl_slice * nr_slices;
|
|
do_div(tmp, HZ);
|
|
bytes_trim = tmp;
|
|
|
|
io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
|
|
|
|
if (!bytes_trim && !io_trim)
|
|
return;
|
|
|
|
if (tg->bytes_disp[rw] >= bytes_trim)
|
|
tg->bytes_disp[rw] -= bytes_trim;
|
|
else
|
|
tg->bytes_disp[rw] = 0;
|
|
|
|
if (tg->io_disp[rw] >= io_trim)
|
|
tg->io_disp[rw] -= io_trim;
|
|
else
|
|
tg->io_disp[rw] = 0;
|
|
|
|
tg->slice_start[rw] += nr_slices * throtl_slice;
|
|
|
|
throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"
|
|
" start=%lu end=%lu jiffies=%lu",
|
|
rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
|
|
tg->slice_start[rw], tg->slice_end[rw], jiffies);
|
|
}
|
|
|
|
static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg,
|
|
struct bio *bio, unsigned long *wait)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
unsigned int io_allowed;
|
|
unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
|
|
u64 tmp;
|
|
|
|
jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
|
|
|
|
/* Slice has just started. Consider one slice interval */
|
|
if (!jiffy_elapsed)
|
|
jiffy_elapsed_rnd = throtl_slice;
|
|
|
|
jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
|
|
|
|
/*
|
|
* jiffy_elapsed_rnd should not be a big value as minimum iops can be
|
|
* 1 then at max jiffy elapsed should be equivalent of 1 second as we
|
|
* will allow dispatch after 1 second and after that slice should
|
|
* have been trimmed.
|
|
*/
|
|
|
|
tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd;
|
|
do_div(tmp, HZ);
|
|
|
|
if (tmp > UINT_MAX)
|
|
io_allowed = UINT_MAX;
|
|
else
|
|
io_allowed = tmp;
|
|
|
|
if (tg->io_disp[rw] + 1 <= io_allowed) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return 1;
|
|
}
|
|
|
|
/* Calc approx time to dispatch */
|
|
jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1;
|
|
|
|
if (jiffy_wait > jiffy_elapsed)
|
|
jiffy_wait = jiffy_wait - jiffy_elapsed;
|
|
else
|
|
jiffy_wait = 1;
|
|
|
|
if (wait)
|
|
*wait = jiffy_wait;
|
|
return 0;
|
|
}
|
|
|
|
static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg,
|
|
struct bio *bio, unsigned long *wait)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
u64 bytes_allowed, extra_bytes, tmp;
|
|
unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
|
|
|
|
jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
|
|
|
|
/* Slice has just started. Consider one slice interval */
|
|
if (!jiffy_elapsed)
|
|
jiffy_elapsed_rnd = throtl_slice;
|
|
|
|
jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
|
|
|
|
tmp = tg->bps[rw] * jiffy_elapsed_rnd;
|
|
do_div(tmp, HZ);
|
|
bytes_allowed = tmp;
|
|
|
|
if (tg->bytes_disp[rw] + bio->bi_size <= bytes_allowed) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return 1;
|
|
}
|
|
|
|
/* Calc approx time to dispatch */
|
|
extra_bytes = tg->bytes_disp[rw] + bio->bi_size - bytes_allowed;
|
|
jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]);
|
|
|
|
if (!jiffy_wait)
|
|
jiffy_wait = 1;
|
|
|
|
/*
|
|
* This wait time is without taking into consideration the rounding
|
|
* up we did. Add that time also.
|
|
*/
|
|
jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed);
|
|
if (wait)
|
|
*wait = jiffy_wait;
|
|
return 0;
|
|
}
|
|
|
|
static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) {
|
|
if (tg->bps[rw] == -1 && tg->iops[rw] == -1)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Returns whether one can dispatch a bio or not. Also returns approx number
|
|
* of jiffies to wait before this bio is with-in IO rate and can be dispatched
|
|
*/
|
|
static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
|
|
struct bio *bio, unsigned long *wait)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
|
|
|
|
/*
|
|
* Currently whole state machine of group depends on first bio
|
|
* queued in the group bio list. So one should not be calling
|
|
* this function with a different bio if there are other bios
|
|
* queued.
|
|
*/
|
|
BUG_ON(tg->nr_queued[rw] && bio != bio_list_peek(&tg->bio_lists[rw]));
|
|
|
|
/* If tg->bps = -1, then BW is unlimited */
|
|
if (tg->bps[rw] == -1 && tg->iops[rw] == -1) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* If previous slice expired, start a new one otherwise renew/extend
|
|
* existing slice to make sure it is at least throtl_slice interval
|
|
* long since now.
|
|
*/
|
|
if (throtl_slice_used(td, tg, rw))
|
|
throtl_start_new_slice(td, tg, rw);
|
|
else {
|
|
if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
|
|
throtl_extend_slice(td, tg, rw, jiffies + throtl_slice);
|
|
}
|
|
|
|
if (tg_with_in_bps_limit(td, tg, bio, &bps_wait)
|
|
&& tg_with_in_iops_limit(td, tg, bio, &iops_wait)) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return 1;
|
|
}
|
|
|
|
max_wait = max(bps_wait, iops_wait);
|
|
|
|
if (wait)
|
|
*wait = max_wait;
|
|
|
|
if (time_before(tg->slice_end[rw], jiffies + max_wait))
|
|
throtl_extend_slice(td, tg, rw, jiffies + max_wait);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes,
|
|
int rw)
|
|
{
|
|
struct throtl_grp *tg = blkg_to_tg(blkg);
|
|
struct tg_stats_cpu *stats_cpu;
|
|
unsigned long flags;
|
|
|
|
/* If per cpu stats are not allocated yet, don't do any accounting. */
|
|
if (tg->stats_cpu == NULL)
|
|
return;
|
|
|
|
/*
|
|
* Disabling interrupts to provide mutual exclusion between two
|
|
* writes on same cpu. It probably is not needed for 64bit. Not
|
|
* optimizing that case yet.
|
|
*/
|
|
local_irq_save(flags);
|
|
|
|
stats_cpu = this_cpu_ptr(tg->stats_cpu);
|
|
|
|
blkg_rwstat_add(&stats_cpu->serviced, rw, 1);
|
|
blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
|
|
/* Charge the bio to the group */
|
|
tg->bytes_disp[rw] += bio->bi_size;
|
|
tg->io_disp[rw]++;
|
|
|
|
throtl_update_dispatch_stats(tg_to_blkg(tg), bio->bi_size, bio->bi_rw);
|
|
}
|
|
|
|
static void throtl_add_bio_tg(struct throtl_data *td, struct throtl_grp *tg,
|
|
struct bio *bio)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
|
|
bio_list_add(&tg->bio_lists[rw], bio);
|
|
/* Take a bio reference on tg */
|
|
blkg_get(tg_to_blkg(tg));
|
|
tg->nr_queued[rw]++;
|
|
td->nr_queued[rw]++;
|
|
throtl_enqueue_tg(td, tg);
|
|
}
|
|
|
|
static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg)
|
|
{
|
|
unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
|
|
struct bio *bio;
|
|
|
|
if ((bio = bio_list_peek(&tg->bio_lists[READ])))
|
|
tg_may_dispatch(td, tg, bio, &read_wait);
|
|
|
|
if ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
|
|
tg_may_dispatch(td, tg, bio, &write_wait);
|
|
|
|
min_wait = min(read_wait, write_wait);
|
|
disptime = jiffies + min_wait;
|
|
|
|
/* Update dispatch time */
|
|
throtl_dequeue_tg(td, tg);
|
|
tg->disptime = disptime;
|
|
throtl_enqueue_tg(td, tg);
|
|
}
|
|
|
|
static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg,
|
|
bool rw, struct bio_list *bl)
|
|
{
|
|
struct bio *bio;
|
|
|
|
bio = bio_list_pop(&tg->bio_lists[rw]);
|
|
tg->nr_queued[rw]--;
|
|
/* Drop bio reference on blkg */
|
|
blkg_put(tg_to_blkg(tg));
|
|
|
|
BUG_ON(td->nr_queued[rw] <= 0);
|
|
td->nr_queued[rw]--;
|
|
|
|
throtl_charge_bio(tg, bio);
|
|
bio_list_add(bl, bio);
|
|
bio->bi_rw |= REQ_THROTTLED;
|
|
|
|
throtl_trim_slice(td, tg, rw);
|
|
}
|
|
|
|
static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg,
|
|
struct bio_list *bl)
|
|
{
|
|
unsigned int nr_reads = 0, nr_writes = 0;
|
|
unsigned int max_nr_reads = throtl_grp_quantum*3/4;
|
|
unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads;
|
|
struct bio *bio;
|
|
|
|
/* Try to dispatch 75% READS and 25% WRITES */
|
|
|
|
while ((bio = bio_list_peek(&tg->bio_lists[READ]))
|
|
&& tg_may_dispatch(td, tg, bio, NULL)) {
|
|
|
|
tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);
|
|
nr_reads++;
|
|
|
|
if (nr_reads >= max_nr_reads)
|
|
break;
|
|
}
|
|
|
|
while ((bio = bio_list_peek(&tg->bio_lists[WRITE]))
|
|
&& tg_may_dispatch(td, tg, bio, NULL)) {
|
|
|
|
tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);
|
|
nr_writes++;
|
|
|
|
if (nr_writes >= max_nr_writes)
|
|
break;
|
|
}
|
|
|
|
return nr_reads + nr_writes;
|
|
}
|
|
|
|
static int throtl_select_dispatch(struct throtl_data *td, struct bio_list *bl)
|
|
{
|
|
unsigned int nr_disp = 0;
|
|
struct throtl_grp *tg;
|
|
struct throtl_rb_root *st = &td->tg_service_tree;
|
|
|
|
while (1) {
|
|
tg = throtl_rb_first(st);
|
|
|
|
if (!tg)
|
|
break;
|
|
|
|
if (time_before(jiffies, tg->disptime))
|
|
break;
|
|
|
|
throtl_dequeue_tg(td, tg);
|
|
|
|
nr_disp += throtl_dispatch_tg(td, tg, bl);
|
|
|
|
if (tg->nr_queued[0] || tg->nr_queued[1]) {
|
|
tg_update_disptime(td, tg);
|
|
throtl_enqueue_tg(td, tg);
|
|
}
|
|
|
|
if (nr_disp >= throtl_quantum)
|
|
break;
|
|
}
|
|
|
|
return nr_disp;
|
|
}
|
|
|
|
static void throtl_process_limit_change(struct throtl_data *td)
|
|
{
|
|
struct request_queue *q = td->queue;
|
|
struct blkcg_gq *blkg, *n;
|
|
|
|
if (!td->limits_changed)
|
|
return;
|
|
|
|
xchg(&td->limits_changed, false);
|
|
|
|
throtl_log(td, "limits changed");
|
|
|
|
list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
|
|
struct throtl_grp *tg = blkg_to_tg(blkg);
|
|
|
|
if (!tg->limits_changed)
|
|
continue;
|
|
|
|
if (!xchg(&tg->limits_changed, false))
|
|
continue;
|
|
|
|
throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu"
|
|
" riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE],
|
|
tg->iops[READ], tg->iops[WRITE]);
|
|
|
|
/*
|
|
* Restart the slices for both READ and WRITES. It
|
|
* might happen that a group's limit are dropped
|
|
* suddenly and we don't want to account recently
|
|
* dispatched IO with new low rate
|
|
*/
|
|
throtl_start_new_slice(td, tg, 0);
|
|
throtl_start_new_slice(td, tg, 1);
|
|
|
|
if (throtl_tg_on_rr(tg))
|
|
tg_update_disptime(td, tg);
|
|
}
|
|
}
|
|
|
|
/* Dispatch throttled bios. Should be called without queue lock held. */
|
|
static int throtl_dispatch(struct request_queue *q)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
unsigned int nr_disp = 0;
|
|
struct bio_list bio_list_on_stack;
|
|
struct bio *bio;
|
|
struct blk_plug plug;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
throtl_process_limit_change(td);
|
|
|
|
if (!total_nr_queued(td))
|
|
goto out;
|
|
|
|
bio_list_init(&bio_list_on_stack);
|
|
|
|
throtl_log(td, "dispatch nr_queued=%u read=%u write=%u",
|
|
total_nr_queued(td), td->nr_queued[READ],
|
|
td->nr_queued[WRITE]);
|
|
|
|
nr_disp = throtl_select_dispatch(td, &bio_list_on_stack);
|
|
|
|
if (nr_disp)
|
|
throtl_log(td, "bios disp=%u", nr_disp);
|
|
|
|
throtl_schedule_next_dispatch(td);
|
|
out:
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
/*
|
|
* If we dispatched some requests, unplug the queue to make sure
|
|
* immediate dispatch
|
|
*/
|
|
if (nr_disp) {
|
|
blk_start_plug(&plug);
|
|
while((bio = bio_list_pop(&bio_list_on_stack)))
|
|
generic_make_request(bio);
|
|
blk_finish_plug(&plug);
|
|
}
|
|
return nr_disp;
|
|
}
|
|
|
|
void blk_throtl_work(struct work_struct *work)
|
|
{
|
|
struct throtl_data *td = container_of(work, struct throtl_data,
|
|
throtl_work.work);
|
|
struct request_queue *q = td->queue;
|
|
|
|
throtl_dispatch(q);
|
|
}
|
|
|
|
/* Call with queue lock held */
|
|
static void
|
|
throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay)
|
|
{
|
|
|
|
struct delayed_work *dwork = &td->throtl_work;
|
|
|
|
/* schedule work if limits changed even if no bio is queued */
|
|
if (total_nr_queued(td) || td->limits_changed) {
|
|
/*
|
|
* We might have a work scheduled to be executed in future.
|
|
* Cancel that and schedule a new one.
|
|
*/
|
|
__cancel_delayed_work(dwork);
|
|
queue_delayed_work(kthrotld_workqueue, dwork, delay);
|
|
throtl_log(td, "schedule work. delay=%lu jiffies=%lu",
|
|
delay, jiffies);
|
|
}
|
|
}
|
|
|
|
static u64 tg_prfill_cpu_rwstat(struct seq_file *sf,
|
|
struct blkg_policy_data *pd, int off)
|
|
{
|
|
struct throtl_grp *tg = pd_to_tg(pd);
|
|
struct blkg_rwstat rwstat = { }, tmp;
|
|
int i, cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
|
|
|
|
tmp = blkg_rwstat_read((void *)sc + off);
|
|
for (i = 0; i < BLKG_RWSTAT_NR; i++)
|
|
rwstat.cnt[i] += tmp.cnt[i];
|
|
}
|
|
|
|
return __blkg_prfill_rwstat(sf, pd, &rwstat);
|
|
}
|
|
|
|
static int tg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,
|
|
struct seq_file *sf)
|
|
{
|
|
struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
|
|
|
|
blkcg_print_blkgs(sf, blkcg, tg_prfill_cpu_rwstat, &blkcg_policy_throtl,
|
|
cft->private, true);
|
|
return 0;
|
|
}
|
|
|
|
static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
struct throtl_grp *tg = pd_to_tg(pd);
|
|
u64 v = *(u64 *)((void *)tg + off);
|
|
|
|
if (v == -1)
|
|
return 0;
|
|
return __blkg_prfill_u64(sf, pd, v);
|
|
}
|
|
|
|
static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
struct throtl_grp *tg = pd_to_tg(pd);
|
|
unsigned int v = *(unsigned int *)((void *)tg + off);
|
|
|
|
if (v == -1)
|
|
return 0;
|
|
return __blkg_prfill_u64(sf, pd, v);
|
|
}
|
|
|
|
static int tg_print_conf_u64(struct cgroup *cgrp, struct cftype *cft,
|
|
struct seq_file *sf)
|
|
{
|
|
blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_u64,
|
|
&blkcg_policy_throtl, cft->private, false);
|
|
return 0;
|
|
}
|
|
|
|
static int tg_print_conf_uint(struct cgroup *cgrp, struct cftype *cft,
|
|
struct seq_file *sf)
|
|
{
|
|
blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_uint,
|
|
&blkcg_policy_throtl, cft->private, false);
|
|
return 0;
|
|
}
|
|
|
|
static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf,
|
|
bool is_u64)
|
|
{
|
|
struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
|
|
struct blkg_conf_ctx ctx;
|
|
struct throtl_grp *tg;
|
|
struct throtl_data *td;
|
|
int ret;
|
|
|
|
ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
|
|
if (ret)
|
|
return ret;
|
|
|
|
tg = blkg_to_tg(ctx.blkg);
|
|
td = ctx.blkg->q->td;
|
|
|
|
if (!ctx.v)
|
|
ctx.v = -1;
|
|
|
|
if (is_u64)
|
|
*(u64 *)((void *)tg + cft->private) = ctx.v;
|
|
else
|
|
*(unsigned int *)((void *)tg + cft->private) = ctx.v;
|
|
|
|
/* XXX: we don't need the following deferred processing */
|
|
xchg(&tg->limits_changed, true);
|
|
xchg(&td->limits_changed, true);
|
|
throtl_schedule_delayed_work(td, 0);
|
|
|
|
blkg_conf_finish(&ctx);
|
|
return 0;
|
|
}
|
|
|
|
static int tg_set_conf_u64(struct cgroup *cgrp, struct cftype *cft,
|
|
const char *buf)
|
|
{
|
|
return tg_set_conf(cgrp, cft, buf, true);
|
|
}
|
|
|
|
static int tg_set_conf_uint(struct cgroup *cgrp, struct cftype *cft,
|
|
const char *buf)
|
|
{
|
|
return tg_set_conf(cgrp, cft, buf, false);
|
|
}
|
|
|
|
static struct cftype throtl_files[] = {
|
|
{
|
|
.name = "throttle.read_bps_device",
|
|
.private = offsetof(struct throtl_grp, bps[READ]),
|
|
.read_seq_string = tg_print_conf_u64,
|
|
.write_string = tg_set_conf_u64,
|
|
.max_write_len = 256,
|
|
},
|
|
{
|
|
.name = "throttle.write_bps_device",
|
|
.private = offsetof(struct throtl_grp, bps[WRITE]),
|
|
.read_seq_string = tg_print_conf_u64,
|
|
.write_string = tg_set_conf_u64,
|
|
.max_write_len = 256,
|
|
},
|
|
{
|
|
.name = "throttle.read_iops_device",
|
|
.private = offsetof(struct throtl_grp, iops[READ]),
|
|
.read_seq_string = tg_print_conf_uint,
|
|
.write_string = tg_set_conf_uint,
|
|
.max_write_len = 256,
|
|
},
|
|
{
|
|
.name = "throttle.write_iops_device",
|
|
.private = offsetof(struct throtl_grp, iops[WRITE]),
|
|
.read_seq_string = tg_print_conf_uint,
|
|
.write_string = tg_set_conf_uint,
|
|
.max_write_len = 256,
|
|
},
|
|
{
|
|
.name = "throttle.io_service_bytes",
|
|
.private = offsetof(struct tg_stats_cpu, service_bytes),
|
|
.read_seq_string = tg_print_cpu_rwstat,
|
|
},
|
|
{
|
|
.name = "throttle.io_serviced",
|
|
.private = offsetof(struct tg_stats_cpu, serviced),
|
|
.read_seq_string = tg_print_cpu_rwstat,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
static void throtl_shutdown_wq(struct request_queue *q)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
|
|
cancel_delayed_work_sync(&td->throtl_work);
|
|
}
|
|
|
|
static struct blkcg_policy blkcg_policy_throtl = {
|
|
.pd_size = sizeof(struct throtl_grp),
|
|
.cftypes = throtl_files,
|
|
|
|
.pd_init_fn = throtl_pd_init,
|
|
.pd_exit_fn = throtl_pd_exit,
|
|
.pd_reset_stats_fn = throtl_pd_reset_stats,
|
|
};
|
|
|
|
bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
struct throtl_grp *tg;
|
|
bool rw = bio_data_dir(bio), update_disptime = true;
|
|
struct blkcg *blkcg;
|
|
bool throttled = false;
|
|
|
|
if (bio->bi_rw & REQ_THROTTLED) {
|
|
bio->bi_rw &= ~REQ_THROTTLED;
|
|
goto out;
|
|
}
|
|
|
|
/* bio_associate_current() needs ioc, try creating */
|
|
create_io_context(GFP_ATOMIC, q->node);
|
|
|
|
/*
|
|
* A throtl_grp pointer retrieved under rcu can be used to access
|
|
* basic fields like stats and io rates. If a group has no rules,
|
|
* just update the dispatch stats in lockless manner and return.
|
|
*/
|
|
rcu_read_lock();
|
|
blkcg = bio_blkcg(bio);
|
|
tg = throtl_lookup_tg(td, blkcg);
|
|
if (tg) {
|
|
if (tg_no_rule_group(tg, rw)) {
|
|
throtl_update_dispatch_stats(tg_to_blkg(tg),
|
|
bio->bi_size, bio->bi_rw);
|
|
goto out_unlock_rcu;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Either group has not been allocated yet or it is not an unlimited
|
|
* IO group
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
tg = throtl_lookup_create_tg(td, blkcg);
|
|
if (unlikely(!tg))
|
|
goto out_unlock;
|
|
|
|
if (tg->nr_queued[rw]) {
|
|
/*
|
|
* There is already another bio queued in same dir. No
|
|
* need to update dispatch time.
|
|
*/
|
|
update_disptime = false;
|
|
goto queue_bio;
|
|
|
|
}
|
|
|
|
/* Bio is with-in rate limit of group */
|
|
if (tg_may_dispatch(td, tg, bio, NULL)) {
|
|
throtl_charge_bio(tg, bio);
|
|
|
|
/*
|
|
* We need to trim slice even when bios are not being queued
|
|
* otherwise it might happen that a bio is not queued for
|
|
* a long time and slice keeps on extending and trim is not
|
|
* called for a long time. Now if limits are reduced suddenly
|
|
* we take into account all the IO dispatched so far at new
|
|
* low rate and * newly queued IO gets a really long dispatch
|
|
* time.
|
|
*
|
|
* So keep on trimming slice even if bio is not queued.
|
|
*/
|
|
throtl_trim_slice(td, tg, rw);
|
|
goto out_unlock;
|
|
}
|
|
|
|
queue_bio:
|
|
throtl_log_tg(td, tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu"
|
|
" iodisp=%u iops=%u queued=%d/%d",
|
|
rw == READ ? 'R' : 'W',
|
|
tg->bytes_disp[rw], bio->bi_size, tg->bps[rw],
|
|
tg->io_disp[rw], tg->iops[rw],
|
|
tg->nr_queued[READ], tg->nr_queued[WRITE]);
|
|
|
|
bio_associate_current(bio);
|
|
throtl_add_bio_tg(q->td, tg, bio);
|
|
throttled = true;
|
|
|
|
if (update_disptime) {
|
|
tg_update_disptime(td, tg);
|
|
throtl_schedule_next_dispatch(td);
|
|
}
|
|
|
|
out_unlock:
|
|
spin_unlock_irq(q->queue_lock);
|
|
out_unlock_rcu:
|
|
rcu_read_unlock();
|
|
out:
|
|
return throttled;
|
|
}
|
|
|
|
/**
|
|
* blk_throtl_drain - drain throttled bios
|
|
* @q: request_queue to drain throttled bios for
|
|
*
|
|
* Dispatch all currently throttled bios on @q through ->make_request_fn().
|
|
*/
|
|
void blk_throtl_drain(struct request_queue *q)
|
|
__releases(q->queue_lock) __acquires(q->queue_lock)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
struct throtl_rb_root *st = &td->tg_service_tree;
|
|
struct throtl_grp *tg;
|
|
struct bio_list bl;
|
|
struct bio *bio;
|
|
|
|
queue_lockdep_assert_held(q);
|
|
|
|
bio_list_init(&bl);
|
|
|
|
while ((tg = throtl_rb_first(st))) {
|
|
throtl_dequeue_tg(td, tg);
|
|
|
|
while ((bio = bio_list_peek(&tg->bio_lists[READ])))
|
|
tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
|
|
while ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
|
|
tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
|
|
}
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
while ((bio = bio_list_pop(&bl)))
|
|
generic_make_request(bio);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
}
|
|
|
|
int blk_throtl_init(struct request_queue *q)
|
|
{
|
|
struct throtl_data *td;
|
|
int ret;
|
|
|
|
td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
|
|
if (!td)
|
|
return -ENOMEM;
|
|
|
|
td->tg_service_tree = THROTL_RB_ROOT;
|
|
td->limits_changed = false;
|
|
INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
|
|
|
|
q->td = td;
|
|
td->queue = q;
|
|
|
|
/* activate policy */
|
|
ret = blkcg_activate_policy(q, &blkcg_policy_throtl);
|
|
if (ret)
|
|
kfree(td);
|
|
return ret;
|
|
}
|
|
|
|
void blk_throtl_exit(struct request_queue *q)
|
|
{
|
|
BUG_ON(!q->td);
|
|
throtl_shutdown_wq(q);
|
|
blkcg_deactivate_policy(q, &blkcg_policy_throtl);
|
|
kfree(q->td);
|
|
}
|
|
|
|
static int __init throtl_init(void)
|
|
{
|
|
kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
|
|
if (!kthrotld_workqueue)
|
|
panic("Failed to create kthrotld\n");
|
|
|
|
return blkcg_policy_register(&blkcg_policy_throtl);
|
|
}
|
|
|
|
module_init(throtl_init);
|