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https://github.com/FEX-Emu/linux.git
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69d60eb96a
Use plug in throttle dispatch also as we are dispatching a bunch of bios in throttle context and some of them might merge. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
1145 lines
28 KiB
C
1145 lines
28 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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/* 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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/* 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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bool limits_changed;
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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
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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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atomic_t limits_changed;
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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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/*
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* This is the common case when there are no blkio cgroups.
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* Avoid lookup in this case
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*/
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if (blkcg == &blkio_root_cgroup)
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tg = &td->root_tg;
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else
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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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tg->iops[READ] = blkcg_get_read_iops(blkcg, tg->blkg.dev);
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tg->iops[WRITE] = blkcg_get_write_iops(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->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];
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nr_slices = time_elapsed / throtl_slice;
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if (!nr_slices)
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return;
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tmp = tg->bps[rw] * throtl_slice * nr_slices;
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do_div(tmp, HZ);
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bytes_trim = tmp;
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io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
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if (!bytes_trim && !io_trim)
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return;
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if (tg->bytes_disp[rw] >= bytes_trim)
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tg->bytes_disp[rw] -= bytes_trim;
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else
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tg->bytes_disp[rw] = 0;
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if (tg->io_disp[rw] >= io_trim)
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tg->io_disp[rw] -= io_trim;
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else
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tg->io_disp[rw] = 0;
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tg->slice_start[rw] += nr_slices * throtl_slice;
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throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"
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" start=%lu end=%lu jiffies=%lu",
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rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
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tg->slice_start[rw], tg->slice_end[rw], jiffies);
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}
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static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg,
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struct bio *bio, unsigned long *wait)
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{
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bool rw = bio_data_dir(bio);
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unsigned int io_allowed;
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unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
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u64 tmp;
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jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
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/* Slice has just started. Consider one slice interval */
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if (!jiffy_elapsed)
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jiffy_elapsed_rnd = throtl_slice;
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jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
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/*
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* jiffy_elapsed_rnd should not be a big value as minimum iops can be
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* 1 then at max jiffy elapsed should be equivalent of 1 second as we
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* will allow dispatch after 1 second and after that slice should
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* have been trimmed.
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*/
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tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd;
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do_div(tmp, HZ);
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if (tmp > UINT_MAX)
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io_allowed = UINT_MAX;
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else
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io_allowed = tmp;
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if (tg->io_disp[rw] + 1 <= io_allowed) {
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if (wait)
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*wait = 0;
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return 1;
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}
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|
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/* Calc approx time to dispatch */
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jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1;
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if (jiffy_wait > jiffy_elapsed)
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jiffy_wait = jiffy_wait - jiffy_elapsed;
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|
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;
|
|
}
|
|
|
|
/*
|
|
* 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_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;
|
|
tg->io_disp[rw]++;
|
|
|
|
/*
|
|
* 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;
|
|
|
|
/* 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 - 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 throtl_grp *tg;
|
|
struct hlist_node *pos, *n;
|
|
|
|
if (!atomic_read(&td->limits_changed))
|
|
return;
|
|
|
|
throtl_log(td, "limit changed =%d", atomic_read(&td->limits_changed));
|
|
|
|
/*
|
|
* Make sure updates from throtl_update_blkio_group_read_bps() group
|
|
* of functions to tg->limits_changed are visible. We do not
|
|
* want update td->limits_changed to be visible but update to
|
|
* tg->limits_changed not being visible yet on this cpu. Hence
|
|
* the read barrier.
|
|
*/
|
|
smp_rmb();
|
|
|
|
hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
|
|
if (throtl_tg_on_rr(tg) && tg->limits_changed) {
|
|
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]);
|
|
tg_update_disptime(td, tg);
|
|
tg->limits_changed = false;
|
|
}
|
|
}
|
|
|
|
smp_mb__before_atomic_dec();
|
|
atomic_dec(&td->limits_changed);
|
|
smp_mb__after_atomic_dec();
|
|
}
|
|
|
|
/* 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=%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) {
|
|
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 */
|
|
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);
|
|
}
|
|
|
|
/*
|
|
* For all update functions, key should be a valid pointer because these
|
|
* update functions are called under blkcg_lock, that means, blkg is
|
|
* valid and in turn key is valid. queue exit path can not race becuase
|
|
* of blkcg_lock
|
|
*
|
|
* Can not take queue lock in update functions as queue lock under blkcg_lock
|
|
* is not allowed. Under other paths we take blkcg_lock under queue_lock.
|
|
*/
|
|
static void throtl_update_blkio_group_read_bps(void *key,
|
|
struct blkio_group *blkg, u64 read_bps)
|
|
{
|
|
struct throtl_data *td = key;
|
|
|
|
tg_of_blkg(blkg)->bps[READ] = read_bps;
|
|
/* Make sure read_bps is updated before setting limits_changed */
|
|
smp_wmb();
|
|
tg_of_blkg(blkg)->limits_changed = true;
|
|
|
|
/* Make sure tg->limits_changed is updated before td->limits_changed */
|
|
smp_mb__before_atomic_inc();
|
|
atomic_inc(&td->limits_changed);
|
|
smp_mb__after_atomic_inc();
|
|
|
|
/* Schedule a work now to process the limit change */
|
|
throtl_schedule_delayed_work(td->queue, 0);
|
|
}
|
|
|
|
static void throtl_update_blkio_group_write_bps(void *key,
|
|
struct blkio_group *blkg, u64 write_bps)
|
|
{
|
|
struct throtl_data *td = key;
|
|
|
|
tg_of_blkg(blkg)->bps[WRITE] = write_bps;
|
|
smp_wmb();
|
|
tg_of_blkg(blkg)->limits_changed = true;
|
|
smp_mb__before_atomic_inc();
|
|
atomic_inc(&td->limits_changed);
|
|
smp_mb__after_atomic_inc();
|
|
throtl_schedule_delayed_work(td->queue, 0);
|
|
}
|
|
|
|
static void throtl_update_blkio_group_read_iops(void *key,
|
|
struct blkio_group *blkg, unsigned int read_iops)
|
|
{
|
|
struct throtl_data *td = key;
|
|
|
|
tg_of_blkg(blkg)->iops[READ] = read_iops;
|
|
smp_wmb();
|
|
tg_of_blkg(blkg)->limits_changed = true;
|
|
smp_mb__before_atomic_inc();
|
|
atomic_inc(&td->limits_changed);
|
|
smp_mb__after_atomic_inc();
|
|
throtl_schedule_delayed_work(td->queue, 0);
|
|
}
|
|
|
|
static void throtl_update_blkio_group_write_iops(void *key,
|
|
struct blkio_group *blkg, unsigned int write_iops)
|
|
{
|
|
struct throtl_data *td = key;
|
|
|
|
tg_of_blkg(blkg)->iops[WRITE] = write_iops;
|
|
smp_wmb();
|
|
tg_of_blkg(blkg)->limits_changed = true;
|
|
smp_mb__before_atomic_inc();
|
|
atomic_inc(&td->limits_changed);
|
|
smp_mb__after_atomic_inc();
|
|
throtl_schedule_delayed_work(td->queue, 0);
|
|
}
|
|
|
|
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,
|
|
.blkio_update_group_read_iops_fn =
|
|
throtl_update_blkio_group_read_iops,
|
|
.blkio_update_group_write_iops_fn =
|
|
throtl_update_blkio_group_write_iops,
|
|
},
|
|
.plid = BLKIO_POLICY_THROTL,
|
|
};
|
|
|
|
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.
|
|
* Still update the disptime if rate limits on this group
|
|
* were changed.
|
|
*/
|
|
if (!tg->limits_changed)
|
|
update_disptime = false;
|
|
else
|
|
tg->limits_changed = 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. bdisp=%u 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]);
|
|
|
|
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;
|
|
atomic_set(&td->limits_changed, 0);
|
|
|
|
/* 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;
|
|
tg->iops[0] = tg->iops[1] = -1;
|
|
|
|
/*
|
|
* Set root group reference to 2. One reference will be dropped when
|
|
* all groups on tg_list are being deleted during queue exit. Other
|
|
* reference will remain there as we don't want to delete this group
|
|
* as it is statically allocated and gets destroyed when throtl_data
|
|
* goes away.
|
|
*/
|
|
atomic_set(&tg->ref, 2);
|
|
hlist_add_head(&tg->tg_node, &td->tg_list);
|
|
td->nr_undestroyed_grps++;
|
|
|
|
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);
|
|
|
|
/* If there are other groups */
|
|
if (td->nr_undestroyed_grps > 0)
|
|
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();
|
|
|
|
/*
|
|
* Just being safe to make sure after previous flush if some body did
|
|
* update limits through cgroup and another work got queued, cancel
|
|
* it.
|
|
*/
|
|
throtl_shutdown_timer_wq(q);
|
|
throtl_td_free(td);
|
|
}
|
|
|
|
static int __init throtl_init(void)
|
|
{
|
|
blkio_policy_register(&blkio_policy_throtl);
|
|
return 0;
|
|
}
|
|
|
|
module_init(throtl_init);
|