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blkio: Core implementation of throttle policy
o Actual implementation of throttling policy in block layer. Currently it implements READ and WRITE bytes per second throttling logic. IOPS throttling comes in later patches. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Vivek Goyal
Jens Axboe
parent
4c9eefa16c
commit
e43473b7f2
@ -77,6 +77,18 @@ config BLK_DEV_INTEGRITY
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T10/SCSI Data Integrity Field or the T13/ATA External Path
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Protection. If in doubt, say N.
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config BLK_DEV_THROTTLING
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bool "Block layer bio throttling support"
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depends on BLK_CGROUP=y && EXPERIMENTAL
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default n
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---help---
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Block layer bio throttling support. It can be used to limit
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the IO rate to a device. IO rate policies are per cgroup and
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one needs to mount and use blkio cgroup controller for creating
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cgroups and specifying per device IO rate policies.
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See Documentation/cgroups/blkio-controller.txt for more information.
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endif # BLOCK
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config BLOCK_COMPAT
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@ -9,6 +9,7 @@ obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \
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obj-$(CONFIG_BLK_DEV_BSG) += bsg.o
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obj-$(CONFIG_BLK_CGROUP) += blk-cgroup.o
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obj-$(CONFIG_BLK_DEV_THROTTLING) += blk-throttle.o
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obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
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obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
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obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o
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@ -382,6 +382,7 @@ void blk_sync_queue(struct request_queue *q)
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del_timer_sync(&q->unplug_timer);
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del_timer_sync(&q->timeout);
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cancel_work_sync(&q->unplug_work);
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throtl_shutdown_timer_wq(q);
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}
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EXPORT_SYMBOL(blk_sync_queue);
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@ -459,6 +460,8 @@ void blk_cleanup_queue(struct request_queue *q)
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if (q->elevator)
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elevator_exit(q->elevator);
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blk_throtl_exit(q);
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blk_put_queue(q);
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}
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EXPORT_SYMBOL(blk_cleanup_queue);
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@ -515,6 +518,11 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
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return NULL;
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}
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if (blk_throtl_init(q)) {
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kmem_cache_free(blk_requestq_cachep, q);
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return NULL;
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}
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setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
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laptop_mode_timer_fn, (unsigned long) q);
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init_timer(&q->unplug_timer);
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@ -1522,6 +1530,15 @@ static inline void __generic_make_request(struct bio *bio)
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goto end_io;
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}
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blk_throtl_bio(q, &bio);
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/*
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* If bio = NULL, bio has been throttled and will be submitted
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* later.
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*/
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if (!bio)
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break;
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trace_block_bio_queue(q, bio);
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ret = q->make_request_fn(q, bio);
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@ -2580,6 +2597,13 @@ int kblockd_schedule_work(struct request_queue *q, struct work_struct *work)
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}
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EXPORT_SYMBOL(kblockd_schedule_work);
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int kblockd_schedule_delayed_work(struct request_queue *q,
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struct delayed_work *dwork, unsigned long delay)
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{
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return queue_delayed_work(kblockd_workqueue, dwork, delay);
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}
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EXPORT_SYMBOL(kblockd_schedule_delayed_work);
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int __init blk_dev_init(void)
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{
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BUILD_BUG_ON(__REQ_NR_BITS > 8 *
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909
block/blk-throttle.c
Normal file
909
block/blk-throttle.c
Normal file
@ -0,0 +1,909 @@
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/*
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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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/* 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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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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struct throtl_grp {
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/* List of throtl groups on the request queue*/
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struct hlist_node tg_node;
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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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struct blkio_group blkg;
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atomic_t ref;
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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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/* Number of bytes disptached in current slice */
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uint64_t bytes_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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};
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struct throtl_data
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{
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/* List of throtl groups */
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struct hlist_head tg_list;
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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 throtl_grp root_tg;
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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 (excluding root group)
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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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};
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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...) \
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blk_add_trace_msg((td)->queue, "throtl %s " fmt, \
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blkg_path(&(tg)->blkg), ##args); \
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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 struct throtl_grp *tg_of_blkg(struct blkio_group *blkg)
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{
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if (blkg)
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return container_of(blkg, struct throtl_grp, blkg);
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return NULL;
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}
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static inline 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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static inline struct throtl_grp *throtl_ref_get_tg(struct throtl_grp *tg)
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{
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atomic_inc(&tg->ref);
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return tg;
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}
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static void throtl_put_tg(struct throtl_grp *tg)
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{
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BUG_ON(atomic_read(&tg->ref) <= 0);
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if (!atomic_dec_and_test(&tg->ref))
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return;
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kfree(tg);
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}
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static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td,
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struct cgroup *cgroup)
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{
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struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
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struct throtl_grp *tg = NULL;
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void *key = td;
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struct backing_dev_info *bdi = &td->queue->backing_dev_info;
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unsigned int major, minor;
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/*
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* TODO: Speed up blkiocg_lookup_group() by maintaining a radix
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* tree of blkg (instead of traversing through hash list all
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* the time.
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*/
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tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key));
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/* Fill in device details for root group */
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if (tg && !tg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
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sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
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tg->blkg.dev = MKDEV(major, minor);
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goto done;
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}
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if (tg)
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goto done;
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tg = kzalloc_node(sizeof(*tg), GFP_ATOMIC, td->queue->node);
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if (!tg)
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goto done;
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INIT_HLIST_NODE(&tg->tg_node);
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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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/*
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* Take the initial reference that will be released on destroy
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* This can be thought of a joint reference by cgroup and
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* request queue which will be dropped by either request queue
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* exit or cgroup deletion path depending on who is exiting first.
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*/
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atomic_set(&tg->ref, 1);
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/* Add group onto cgroup list */
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sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
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blkiocg_add_blkio_group(blkcg, &tg->blkg, (void *)td,
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MKDEV(major, minor), BLKIO_POLICY_THROTL);
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tg->bps[READ] = blkcg_get_read_bps(blkcg, tg->blkg.dev);
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tg->bps[WRITE] = blkcg_get_write_bps(blkcg, tg->blkg.dev);
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hlist_add_head(&tg->tg_node, &td->tg_list);
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td->nr_undestroyed_grps++;
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done:
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return tg;
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}
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static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
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{
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struct cgroup *cgroup;
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struct throtl_grp *tg = NULL;
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rcu_read_lock();
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cgroup = task_cgroup(current, blkio_subsys_id);
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tg = throtl_find_alloc_tg(td, cgroup);
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if (!tg)
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tg = &td->root_tg;
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rcu_read_unlock();
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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->queue, 0);
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else
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throtl_schedule_delayed_work(td->queue,
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(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->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_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, bytes_trim, time_elapsed;
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|
||||
BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
|
||||
|
||||
/*
|
||||
* If bps are unlimited (-1), then time slice don't get
|
||||
* renewed. Don't try to trim the slice if slice is used. A new
|
||||
* slice will start when appropriate.
|
||||
*/
|
||||
if (throtl_slice_used(td, tg, rw))
|
||||
return;
|
||||
|
||||
time_elapsed = jiffies - tg->slice_start[rw];
|
||||
|
||||
nr_slices = time_elapsed / throtl_slice;
|
||||
|
||||
if (!nr_slices)
|
||||
return;
|
||||
|
||||
bytes_trim = (tg->bps[rw] * throtl_slice * nr_slices)/HZ;
|
||||
|
||||
if (!bytes_trim)
|
||||
return;
|
||||
|
||||
if (tg->bytes_disp[rw] >= bytes_trim)
|
||||
tg->bytes_disp[rw] -= bytes_trim;
|
||||
else
|
||||
tg->bytes_disp[rw] = 0;
|
||||
|
||||
tg->slice_start[rw] += nr_slices * throtl_slice;
|
||||
|
||||
throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%lu"
|
||||
" start=%lu end=%lu jiffies=%lu",
|
||||
rw == READ ? 'R' : 'W', nr_slices, bytes_trim,
|
||||
tg->slice_start[rw], tg->slice_end[rw], jiffies);
|
||||
}
|
||||
|
||||
/*
|
||||
* 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);
|
||||
u64 bytes_allowed, extra_bytes;
|
||||
unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
|
||||
|
||||
/*
|
||||
* 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) {
|
||||
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);
|
||||
}
|
||||
|
||||
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);
|
||||
|
||||
bytes_allowed = (tg->bps[rw] * jiffies_to_msecs(jiffy_elapsed_rnd))
|
||||
/ MSEC_PER_SEC;
|
||||
|
||||
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;
|
||||
|
||||
if (time_before(tg->slice_end[rw], jiffies + jiffy_wait))
|
||||
throtl_extend_slice(td, tg, rw, jiffies + jiffy_wait);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
|
||||
{
|
||||
bool rw = bio_data_dir(bio);
|
||||
bool sync = bio->bi_rw & REQ_SYNC;
|
||||
|
||||
/* Charge the bio to the group */
|
||||
tg->bytes_disp[rw] += bio->bi_size;
|
||||
|
||||
/*
|
||||
* TODO: This will take blkg->stats_lock. Figure out a way
|
||||
* to avoid this cost.
|
||||
*/
|
||||
blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size, rw, sync);
|
||||
|
||||
}
|
||||
|
||||
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 */
|
||||
throtl_ref_get_tg(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;
|
||||
|
||||
/*
|
||||
* If group is already on active tree, then update dispatch time
|
||||
* only if it is lesser than existing dispatch time. Otherwise
|
||||
* always update the dispatch time
|
||||
*/
|
||||
|
||||
if (throtl_tg_on_rr(tg) && time_before(disptime, tg->disptime))
|
||||
return;
|
||||
|
||||
/* 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 tg */
|
||||
throtl_put_tg(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 - 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;
|
||||
}
|
||||
|
||||
/* 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;
|
||||
|
||||
spin_lock_irq(q->queue_lock);
|
||||
|
||||
if (!total_nr_queued(td))
|
||||
goto out;
|
||||
|
||||
bio_list_init(&bio_list_on_stack);
|
||||
|
||||
throtl_log(td, "dispatch nr_queued=%lu 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) {
|
||||
while((bio = bio_list_pop(&bio_list_on_stack)))
|
||||
generic_make_request(bio);
|
||||
blk_unplug(q);
|
||||
}
|
||||
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 */
|
||||
void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay)
|
||||
{
|
||||
|
||||
struct throtl_data *td = q->td;
|
||||
struct delayed_work *dwork = &td->throtl_work;
|
||||
|
||||
if (total_nr_queued(td) > 0) {
|
||||
/*
|
||||
* We might have a work scheduled to be executed in future.
|
||||
* Cancel that and schedule a new one.
|
||||
*/
|
||||
__cancel_delayed_work(dwork);
|
||||
kblockd_schedule_delayed_work(q, dwork, delay);
|
||||
throtl_log(td, "schedule work. delay=%lu jiffies=%lu",
|
||||
delay, jiffies);
|
||||
}
|
||||
}
|
||||
EXPORT_SYMBOL(throtl_schedule_delayed_work);
|
||||
|
||||
static void
|
||||
throtl_destroy_tg(struct throtl_data *td, struct throtl_grp *tg)
|
||||
{
|
||||
/* Something wrong if we are trying to remove same group twice */
|
||||
BUG_ON(hlist_unhashed(&tg->tg_node));
|
||||
|
||||
hlist_del_init(&tg->tg_node);
|
||||
|
||||
/*
|
||||
* Put the reference taken at the time of creation so that when all
|
||||
* queues are gone, group can be destroyed.
|
||||
*/
|
||||
throtl_put_tg(tg);
|
||||
td->nr_undestroyed_grps--;
|
||||
}
|
||||
|
||||
static void throtl_release_tgs(struct throtl_data *td)
|
||||
{
|
||||
struct hlist_node *pos, *n;
|
||||
struct throtl_grp *tg;
|
||||
|
||||
hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
|
||||
/*
|
||||
* If cgroup removal path got to blk_group first and removed
|
||||
* it from cgroup list, then it will take care of destroying
|
||||
* cfqg also.
|
||||
*/
|
||||
if (!blkiocg_del_blkio_group(&tg->blkg))
|
||||
throtl_destroy_tg(td, tg);
|
||||
}
|
||||
}
|
||||
|
||||
static void throtl_td_free(struct throtl_data *td)
|
||||
{
|
||||
kfree(td);
|
||||
}
|
||||
|
||||
/*
|
||||
* Blk cgroup controller notification saying that blkio_group object is being
|
||||
* delinked as associated cgroup object is going away. That also means that
|
||||
* no new IO will come in this group. So get rid of this group as soon as
|
||||
* any pending IO in the group is finished.
|
||||
*
|
||||
* This function is called under rcu_read_lock(). key is the rcu protected
|
||||
* pointer. That means "key" is a valid throtl_data pointer as long as we are
|
||||
* rcu read lock.
|
||||
*
|
||||
* "key" was fetched from blkio_group under blkio_cgroup->lock. That means
|
||||
* it should not be NULL as even if queue was going away, cgroup deltion
|
||||
* path got to it first.
|
||||
*/
|
||||
void throtl_unlink_blkio_group(void *key, struct blkio_group *blkg)
|
||||
{
|
||||
unsigned long flags;
|
||||
struct throtl_data *td = key;
|
||||
|
||||
spin_lock_irqsave(td->queue->queue_lock, flags);
|
||||
throtl_destroy_tg(td, tg_of_blkg(blkg));
|
||||
spin_unlock_irqrestore(td->queue->queue_lock, flags);
|
||||
}
|
||||
|
||||
static void throtl_update_blkio_group_read_bps (struct blkio_group *blkg,
|
||||
u64 read_bps)
|
||||
{
|
||||
tg_of_blkg(blkg)->bps[READ] = read_bps;
|
||||
}
|
||||
|
||||
static void throtl_update_blkio_group_write_bps (struct blkio_group *blkg,
|
||||
u64 write_bps)
|
||||
{
|
||||
tg_of_blkg(blkg)->bps[WRITE] = write_bps;
|
||||
}
|
||||
|
||||
void throtl_shutdown_timer_wq(struct request_queue *q)
|
||||
{
|
||||
struct throtl_data *td = q->td;
|
||||
|
||||
cancel_delayed_work_sync(&td->throtl_work);
|
||||
}
|
||||
|
||||
static struct blkio_policy_type blkio_policy_throtl = {
|
||||
.ops = {
|
||||
.blkio_unlink_group_fn = throtl_unlink_blkio_group,
|
||||
.blkio_update_group_read_bps_fn =
|
||||
throtl_update_blkio_group_read_bps,
|
||||
.blkio_update_group_write_bps_fn =
|
||||
throtl_update_blkio_group_write_bps,
|
||||
},
|
||||
};
|
||||
|
||||
int blk_throtl_bio(struct request_queue *q, struct bio **biop)
|
||||
{
|
||||
struct throtl_data *td = q->td;
|
||||
struct throtl_grp *tg;
|
||||
struct bio *bio = *biop;
|
||||
bool rw = bio_data_dir(bio), update_disptime = true;
|
||||
|
||||
if (bio->bi_rw & REQ_THROTTLED) {
|
||||
bio->bi_rw &= ~REQ_THROTTLED;
|
||||
return 0;
|
||||
}
|
||||
|
||||
spin_lock_irq(q->queue_lock);
|
||||
tg = throtl_get_tg(td);
|
||||
|
||||
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);
|
||||
goto out;
|
||||
}
|
||||
|
||||
queue_bio:
|
||||
throtl_log_tg(td, tg, "[%c] bio. disp=%u sz=%u bps=%llu"
|
||||
" queued=%d/%d", rw == READ ? 'R' : 'W',
|
||||
tg->bytes_disp[rw], bio->bi_size, tg->bps[rw],
|
||||
tg->nr_queued[READ], tg->nr_queued[WRITE]);
|
||||
|
||||
throtl_add_bio_tg(q->td, tg, bio);
|
||||
*biop = NULL;
|
||||
|
||||
if (update_disptime) {
|
||||
tg_update_disptime(td, tg);
|
||||
throtl_schedule_next_dispatch(td);
|
||||
}
|
||||
|
||||
out:
|
||||
spin_unlock_irq(q->queue_lock);
|
||||
return 0;
|
||||
}
|
||||
|
||||
int blk_throtl_init(struct request_queue *q)
|
||||
{
|
||||
struct throtl_data *td;
|
||||
struct throtl_grp *tg;
|
||||
|
||||
td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
|
||||
if (!td)
|
||||
return -ENOMEM;
|
||||
|
||||
INIT_HLIST_HEAD(&td->tg_list);
|
||||
td->tg_service_tree = THROTL_RB_ROOT;
|
||||
|
||||
/* Init root group */
|
||||
tg = &td->root_tg;
|
||||
INIT_HLIST_NODE(&tg->tg_node);
|
||||
RB_CLEAR_NODE(&tg->rb_node);
|
||||
bio_list_init(&tg->bio_lists[0]);
|
||||
bio_list_init(&tg->bio_lists[1]);
|
||||
|
||||
/* Practically unlimited BW */
|
||||
tg->bps[0] = tg->bps[1] = -1;
|
||||
atomic_set(&tg->ref, 1);
|
||||
|
||||
INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
|
||||
|
||||
rcu_read_lock();
|
||||
blkiocg_add_blkio_group(&blkio_root_cgroup, &tg->blkg, (void *)td,
|
||||
0, BLKIO_POLICY_THROTL);
|
||||
rcu_read_unlock();
|
||||
|
||||
/* Attach throtl data to request queue */
|
||||
td->queue = q;
|
||||
q->td = td;
|
||||
return 0;
|
||||
}
|
||||
|
||||
void blk_throtl_exit(struct request_queue *q)
|
||||
{
|
||||
struct throtl_data *td = q->td;
|
||||
bool wait = false;
|
||||
|
||||
BUG_ON(!td);
|
||||
|
||||
throtl_shutdown_timer_wq(q);
|
||||
|
||||
spin_lock_irq(q->queue_lock);
|
||||
throtl_release_tgs(td);
|
||||
blkiocg_del_blkio_group(&td->root_tg.blkg);
|
||||
|
||||
/* If there are other groups */
|
||||
if (td->nr_undestroyed_grps >= 1)
|
||||
wait = true;
|
||||
|
||||
spin_unlock_irq(q->queue_lock);
|
||||
|
||||
/*
|
||||
* Wait for tg->blkg->key accessors to exit their grace periods.
|
||||
* Do this wait only if there are other undestroyed groups out
|
||||
* there (other than root group). This can happen if cgroup deletion
|
||||
* path claimed the responsibility of cleaning up a group before
|
||||
* queue cleanup code get to the group.
|
||||
*
|
||||
* Do not call synchronize_rcu() unconditionally as there are drivers
|
||||
* which create/delete request queue hundreds of times during scan/boot
|
||||
* and synchronize_rcu() can take significant time and slow down boot.
|
||||
*/
|
||||
if (wait)
|
||||
synchronize_rcu();
|
||||
throtl_td_free(td);
|
||||
}
|
||||
|
||||
static int __init throtl_init(void)
|
||||
{
|
||||
blkio_policy_register(&blkio_policy_throtl);
|
||||
return 0;
|
||||
}
|
||||
|
||||
module_init(throtl_init);
|
||||
@ -130,6 +130,8 @@ enum rq_flag_bits {
|
||||
/* bio only flags */
|
||||
__REQ_UNPLUG, /* unplug the immediately after submission */
|
||||
__REQ_RAHEAD, /* read ahead, can fail anytime */
|
||||
__REQ_THROTTLED, /* This bio has already been subjected to
|
||||
* throttling rules. Don't do it again. */
|
||||
|
||||
/* request only flags */
|
||||
__REQ_SORTED, /* elevator knows about this request */
|
||||
@ -172,6 +174,7 @@ enum rq_flag_bits {
|
||||
|
||||
#define REQ_UNPLUG (1 << __REQ_UNPLUG)
|
||||
#define REQ_RAHEAD (1 << __REQ_RAHEAD)
|
||||
#define REQ_THROTTLED (1 << __REQ_THROTTLED)
|
||||
|
||||
#define REQ_SORTED (1 << __REQ_SORTED)
|
||||
#define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
|
||||
|
||||
@ -371,6 +371,11 @@ struct request_queue
|
||||
#if defined(CONFIG_BLK_DEV_BSG)
|
||||
struct bsg_class_device bsg_dev;
|
||||
#endif
|
||||
|
||||
#ifdef CONFIG_BLK_DEV_THROTTLING
|
||||
/* Throttle data */
|
||||
struct throtl_data *td;
|
||||
#endif
|
||||
};
|
||||
|
||||
#define QUEUE_FLAG_CLUSTER 0 /* cluster several segments into 1 */
|
||||
@ -1131,6 +1136,7 @@ static inline void put_dev_sector(Sector p)
|
||||
|
||||
struct work_struct;
|
||||
int kblockd_schedule_work(struct request_queue *q, struct work_struct *work);
|
||||
int kblockd_schedule_delayed_work(struct request_queue *q, struct delayed_work *dwork, unsigned long delay);
|
||||
|
||||
#ifdef CONFIG_BLK_CGROUP
|
||||
/*
|
||||
@ -1174,6 +1180,24 @@ static inline uint64_t rq_io_start_time_ns(struct request *req)
|
||||
}
|
||||
#endif
|
||||
|
||||
#ifdef CONFIG_BLK_DEV_THROTTLING
|
||||
extern int blk_throtl_init(struct request_queue *q);
|
||||
extern void blk_throtl_exit(struct request_queue *q);
|
||||
extern int blk_throtl_bio(struct request_queue *q, struct bio **bio);
|
||||
extern void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay);
|
||||
extern void throtl_shutdown_timer_wq(struct request_queue *q);
|
||||
#else /* CONFIG_BLK_DEV_THROTTLING */
|
||||
static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
|
||||
{
|
||||
return 0;
|
||||
}
|
||||
|
||||
static inline int blk_throtl_init(struct request_queue *q) { return 0; }
|
||||
static inline int blk_throtl_exit(struct request_queue *q) { return 0; }
|
||||
static inline void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay) {}
|
||||
static inline void throtl_shutdown_timer_wq(struct request_queue *q) {}
|
||||
#endif /* CONFIG_BLK_DEV_THROTTLING */
|
||||
|
||||
#define MODULE_ALIAS_BLOCKDEV(major,minor) \
|
||||
MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
|
||||
#define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \
|
||||
|
||||
@ -634,11 +634,14 @@ config BLK_CGROUP
|
||||
|
||||
Currently, CFQ IO scheduler uses it to recognize task groups and
|
||||
control disk bandwidth allocation (proportional time slice allocation)
|
||||
to such task groups.
|
||||
to such task groups. It is also used by bio throttling logic in
|
||||
block layer to implement upper limit in IO rates on a device.
|
||||
|
||||
This option only enables generic Block IO controller infrastructure.
|
||||
One needs to also enable actual IO controlling logic in CFQ for it
|
||||
to take effect. (CONFIG_CFQ_GROUP_IOSCHED=y).
|
||||
One needs to also enable actual IO controlling logic/policy. For
|
||||
enabling proportional weight division of disk bandwidth in CFQ seti
|
||||
CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
|
||||
CONFIG_BLK_THROTTLE=y.
|
||||
|
||||
See Documentation/cgroups/blkio-controller.txt for more information.
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user