7a4dd281ec
blkg->dev is dev_t recording the device number of the block device for the associated request_queue. It is used to identify the associated block device when printing out configuration or stats. This is redundant to begin with. A blkg is an association between a cgroup and a request_queue and it of course is possible to reach request_queue from blkg and synchronization conventions are in place for safe q dereferencing, so this shouldn't be necessary from the beginning. Furthermore, it's initialized by sscanf()ing the device name of backing_dev_info. The mind boggles. Anyways, if blkg is visible under rcu lock, we *know* that the associated request_queue hasn't gone away yet and its bdi is registered and alive - blkg can't be created for request_queue which hasn't been fully initialized and it can't go away before blkg is removed. Let stat and conf read functions get device name from blkg->q->backing_dev_info.dev and pass it down to printing functions and remove blkg->dev. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
1244 lines
31 KiB
C
1244 lines
31 KiB
C
/*
|
|
* Interface for controlling IO bandwidth on a request queue
|
|
*
|
|
* Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com>
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/blkdev.h>
|
|
#include <linux/bio.h>
|
|
#include <linux/blktrace_api.h>
|
|
#include "blk-cgroup.h"
|
|
#include "blk.h"
|
|
|
|
/* Max dispatch from a group in 1 round */
|
|
static int throtl_grp_quantum = 8;
|
|
|
|
/* Total max dispatch from all groups in one round */
|
|
static int throtl_quantum = 32;
|
|
|
|
/* Throttling is performed over 100ms slice and after that slice is renewed */
|
|
static unsigned long throtl_slice = HZ/10; /* 100 ms */
|
|
|
|
/* A workqueue to queue throttle related work */
|
|
static struct workqueue_struct *kthrotld_workqueue;
|
|
static void throtl_schedule_delayed_work(struct throtl_data *td,
|
|
unsigned long delay);
|
|
|
|
struct throtl_rb_root {
|
|
struct rb_root rb;
|
|
struct rb_node *left;
|
|
unsigned int count;
|
|
unsigned long min_disptime;
|
|
};
|
|
|
|
#define THROTL_RB_ROOT (struct throtl_rb_root) { .rb = RB_ROOT, .left = NULL, \
|
|
.count = 0, .min_disptime = 0}
|
|
|
|
#define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
|
|
|
|
struct throtl_grp {
|
|
/* List of throtl groups on the request queue*/
|
|
struct hlist_node tg_node;
|
|
|
|
/* active throtl group service_tree member */
|
|
struct rb_node rb_node;
|
|
|
|
/*
|
|
* Dispatch time in jiffies. This is the estimated time when group
|
|
* will unthrottle and is ready to dispatch more bio. It is used as
|
|
* key to sort active groups in service tree.
|
|
*/
|
|
unsigned long disptime;
|
|
|
|
struct blkio_group blkg;
|
|
atomic_t ref;
|
|
unsigned int flags;
|
|
|
|
/* Two lists for READ and WRITE */
|
|
struct bio_list bio_lists[2];
|
|
|
|
/* Number of queued bios on READ and WRITE lists */
|
|
unsigned int nr_queued[2];
|
|
|
|
/* bytes per second rate limits */
|
|
uint64_t bps[2];
|
|
|
|
/* IOPS limits */
|
|
unsigned int iops[2];
|
|
|
|
/* Number of bytes disptached in current slice */
|
|
uint64_t bytes_disp[2];
|
|
/* Number of bio's dispatched in current slice */
|
|
unsigned int io_disp[2];
|
|
|
|
/* When did we start a new slice */
|
|
unsigned long slice_start[2];
|
|
unsigned long slice_end[2];
|
|
|
|
/* Some throttle limits got updated for the group */
|
|
int limits_changed;
|
|
|
|
struct rcu_head rcu_head;
|
|
};
|
|
|
|
struct throtl_data
|
|
{
|
|
/* List of throtl groups */
|
|
struct hlist_head tg_list;
|
|
|
|
/* service tree for active throtl groups */
|
|
struct throtl_rb_root tg_service_tree;
|
|
|
|
struct throtl_grp *root_tg;
|
|
struct request_queue *queue;
|
|
|
|
/* Total Number of queued bios on READ and WRITE lists */
|
|
unsigned int nr_queued[2];
|
|
|
|
/*
|
|
* number of total undestroyed groups
|
|
*/
|
|
unsigned int nr_undestroyed_grps;
|
|
|
|
/* Work for dispatching throttled bios */
|
|
struct delayed_work throtl_work;
|
|
|
|
int limits_changed;
|
|
};
|
|
|
|
enum tg_state_flags {
|
|
THROTL_TG_FLAG_on_rr = 0, /* on round-robin busy list */
|
|
};
|
|
|
|
#define THROTL_TG_FNS(name) \
|
|
static inline void throtl_mark_tg_##name(struct throtl_grp *tg) \
|
|
{ \
|
|
(tg)->flags |= (1 << THROTL_TG_FLAG_##name); \
|
|
} \
|
|
static inline void throtl_clear_tg_##name(struct throtl_grp *tg) \
|
|
{ \
|
|
(tg)->flags &= ~(1 << THROTL_TG_FLAG_##name); \
|
|
} \
|
|
static inline int throtl_tg_##name(const struct throtl_grp *tg) \
|
|
{ \
|
|
return ((tg)->flags & (1 << THROTL_TG_FLAG_##name)) != 0; \
|
|
}
|
|
|
|
THROTL_TG_FNS(on_rr);
|
|
|
|
#define throtl_log_tg(td, tg, fmt, args...) \
|
|
blk_add_trace_msg((td)->queue, "throtl %s " fmt, \
|
|
blkg_path(&(tg)->blkg), ##args); \
|
|
|
|
#define throtl_log(td, fmt, args...) \
|
|
blk_add_trace_msg((td)->queue, "throtl " fmt, ##args)
|
|
|
|
static inline struct throtl_grp *tg_of_blkg(struct blkio_group *blkg)
|
|
{
|
|
if (blkg)
|
|
return container_of(blkg, struct throtl_grp, blkg);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static inline unsigned int total_nr_queued(struct throtl_data *td)
|
|
{
|
|
return td->nr_queued[0] + td->nr_queued[1];
|
|
}
|
|
|
|
static inline struct throtl_grp *throtl_ref_get_tg(struct throtl_grp *tg)
|
|
{
|
|
atomic_inc(&tg->ref);
|
|
return tg;
|
|
}
|
|
|
|
static void throtl_free_tg(struct rcu_head *head)
|
|
{
|
|
struct throtl_grp *tg;
|
|
|
|
tg = container_of(head, struct throtl_grp, rcu_head);
|
|
free_percpu(tg->blkg.stats_cpu);
|
|
kfree(tg);
|
|
}
|
|
|
|
static void throtl_put_tg(struct throtl_grp *tg)
|
|
{
|
|
BUG_ON(atomic_read(&tg->ref) <= 0);
|
|
if (!atomic_dec_and_test(&tg->ref))
|
|
return;
|
|
|
|
/*
|
|
* A group is freed in rcu manner. But having an rcu lock does not
|
|
* mean that one can access all the fields of blkg and assume these
|
|
* are valid. For example, don't try to follow throtl_data and
|
|
* request queue links.
|
|
*
|
|
* Having a reference to blkg under an rcu allows acess to only
|
|
* values local to groups like group stats and group rate limits
|
|
*/
|
|
call_rcu(&tg->rcu_head, throtl_free_tg);
|
|
}
|
|
|
|
static struct blkio_group *throtl_alloc_blkio_group(struct request_queue *q,
|
|
struct blkio_cgroup *blkcg)
|
|
{
|
|
struct throtl_grp *tg;
|
|
|
|
tg = kzalloc_node(sizeof(*tg), GFP_ATOMIC, q->node);
|
|
if (!tg)
|
|
return NULL;
|
|
|
|
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]);
|
|
tg->limits_changed = false;
|
|
|
|
tg->bps[READ] = -1;
|
|
tg->bps[WRITE] = -1;
|
|
tg->iops[READ] = -1;
|
|
tg->iops[WRITE] = -1;
|
|
|
|
/*
|
|
* Take the initial reference that will be released on destroy
|
|
* This can be thought of a joint reference by cgroup and
|
|
* request queue which will be dropped by either request queue
|
|
* exit or cgroup deletion path depending on who is exiting first.
|
|
*/
|
|
atomic_set(&tg->ref, 1);
|
|
|
|
return &tg->blkg;
|
|
}
|
|
|
|
static void throtl_link_blkio_group(struct request_queue *q,
|
|
struct blkio_group *blkg)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
struct throtl_grp *tg = tg_of_blkg(blkg);
|
|
|
|
hlist_add_head(&tg->tg_node, &td->tg_list);
|
|
td->nr_undestroyed_grps++;
|
|
}
|
|
|
|
static struct
|
|
throtl_grp *throtl_lookup_tg(struct throtl_data *td, struct blkio_cgroup *blkcg)
|
|
{
|
|
/*
|
|
* This is the common case when there are no blkio cgroups.
|
|
* Avoid lookup in this case
|
|
*/
|
|
if (blkcg == &blkio_root_cgroup)
|
|
return td->root_tg;
|
|
|
|
return tg_of_blkg(blkg_lookup(blkcg, td->queue, BLKIO_POLICY_THROTL));
|
|
}
|
|
|
|
static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
|
|
struct blkio_cgroup *blkcg)
|
|
{
|
|
struct request_queue *q = td->queue;
|
|
struct throtl_grp *tg = NULL;
|
|
|
|
/*
|
|
* This is the common case when there are no blkio cgroups.
|
|
* Avoid lookup in this case
|
|
*/
|
|
if (blkcg == &blkio_root_cgroup) {
|
|
tg = td->root_tg;
|
|
} else {
|
|
struct blkio_group *blkg;
|
|
|
|
blkg = blkg_lookup_create(blkcg, q, BLKIO_POLICY_THROTL, false);
|
|
|
|
/* if %NULL and @q is alive, fall back to root_tg */
|
|
if (!IS_ERR(blkg))
|
|
tg = tg_of_blkg(blkg);
|
|
else if (!blk_queue_dead(q))
|
|
tg = td->root_tg;
|
|
}
|
|
|
|
return tg;
|
|
}
|
|
|
|
static struct throtl_grp *throtl_rb_first(struct throtl_rb_root *root)
|
|
{
|
|
/* Service tree is empty */
|
|
if (!root->count)
|
|
return NULL;
|
|
|
|
if (!root->left)
|
|
root->left = rb_first(&root->rb);
|
|
|
|
if (root->left)
|
|
return rb_entry_tg(root->left);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void rb_erase_init(struct rb_node *n, struct rb_root *root)
|
|
{
|
|
rb_erase(n, root);
|
|
RB_CLEAR_NODE(n);
|
|
}
|
|
|
|
static void throtl_rb_erase(struct rb_node *n, struct throtl_rb_root *root)
|
|
{
|
|
if (root->left == n)
|
|
root->left = NULL;
|
|
rb_erase_init(n, &root->rb);
|
|
--root->count;
|
|
}
|
|
|
|
static void update_min_dispatch_time(struct throtl_rb_root *st)
|
|
{
|
|
struct throtl_grp *tg;
|
|
|
|
tg = throtl_rb_first(st);
|
|
if (!tg)
|
|
return;
|
|
|
|
st->min_disptime = tg->disptime;
|
|
}
|
|
|
|
static void
|
|
tg_service_tree_add(struct throtl_rb_root *st, struct throtl_grp *tg)
|
|
{
|
|
struct rb_node **node = &st->rb.rb_node;
|
|
struct rb_node *parent = NULL;
|
|
struct throtl_grp *__tg;
|
|
unsigned long key = tg->disptime;
|
|
int left = 1;
|
|
|
|
while (*node != NULL) {
|
|
parent = *node;
|
|
__tg = rb_entry_tg(parent);
|
|
|
|
if (time_before(key, __tg->disptime))
|
|
node = &parent->rb_left;
|
|
else {
|
|
node = &parent->rb_right;
|
|
left = 0;
|
|
}
|
|
}
|
|
|
|
if (left)
|
|
st->left = &tg->rb_node;
|
|
|
|
rb_link_node(&tg->rb_node, parent, node);
|
|
rb_insert_color(&tg->rb_node, &st->rb);
|
|
}
|
|
|
|
static void __throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
|
|
{
|
|
struct throtl_rb_root *st = &td->tg_service_tree;
|
|
|
|
tg_service_tree_add(st, tg);
|
|
throtl_mark_tg_on_rr(tg);
|
|
st->count++;
|
|
}
|
|
|
|
static void throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
|
|
{
|
|
if (!throtl_tg_on_rr(tg))
|
|
__throtl_enqueue_tg(td, tg);
|
|
}
|
|
|
|
static void __throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
|
|
{
|
|
throtl_rb_erase(&tg->rb_node, &td->tg_service_tree);
|
|
throtl_clear_tg_on_rr(tg);
|
|
}
|
|
|
|
static void throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
|
|
{
|
|
if (throtl_tg_on_rr(tg))
|
|
__throtl_dequeue_tg(td, tg);
|
|
}
|
|
|
|
static void throtl_schedule_next_dispatch(struct throtl_data *td)
|
|
{
|
|
struct throtl_rb_root *st = &td->tg_service_tree;
|
|
|
|
/*
|
|
* If there are more bios pending, schedule more work.
|
|
*/
|
|
if (!total_nr_queued(td))
|
|
return;
|
|
|
|
BUG_ON(!st->count);
|
|
|
|
update_min_dispatch_time(st);
|
|
|
|
if (time_before_eq(st->min_disptime, jiffies))
|
|
throtl_schedule_delayed_work(td, 0);
|
|
else
|
|
throtl_schedule_delayed_work(td, (st->min_disptime - jiffies));
|
|
}
|
|
|
|
static inline void
|
|
throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
|
|
{
|
|
tg->bytes_disp[rw] = 0;
|
|
tg->io_disp[rw] = 0;
|
|
tg->slice_start[rw] = jiffies;
|
|
tg->slice_end[rw] = jiffies + throtl_slice;
|
|
throtl_log_tg(td, tg, "[%c] new slice start=%lu end=%lu jiffies=%lu",
|
|
rw == READ ? 'R' : 'W', tg->slice_start[rw],
|
|
tg->slice_end[rw], jiffies);
|
|
}
|
|
|
|
static inline void throtl_set_slice_end(struct throtl_data *td,
|
|
struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
|
|
{
|
|
tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
|
|
}
|
|
|
|
static inline void throtl_extend_slice(struct throtl_data *td,
|
|
struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
|
|
{
|
|
tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
|
|
throtl_log_tg(td, tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu",
|
|
rw == READ ? 'R' : 'W', tg->slice_start[rw],
|
|
tg->slice_end[rw], jiffies);
|
|
}
|
|
|
|
/* Determine if previously allocated or extended slice is complete or not */
|
|
static bool
|
|
throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw)
|
|
{
|
|
if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* Trim the used slices and adjust slice start accordingly */
|
|
static inline void
|
|
throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
|
|
{
|
|
unsigned long nr_slices, time_elapsed, io_trim;
|
|
u64 bytes_trim, tmp;
|
|
|
|
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;
|
|
|
|
/*
|
|
* A bio has been dispatched. Also adjust slice_end. It might happen
|
|
* that initially cgroup limit was very low resulting in high
|
|
* slice_end, but later limit was bumped up and bio was dispached
|
|
* sooner, then we need to reduce slice_end. A high bogus slice_end
|
|
* is bad because it does not allow new slice to start.
|
|
*/
|
|
|
|
throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice);
|
|
|
|
time_elapsed = jiffies - tg->slice_start[rw];
|
|
|
|
nr_slices = time_elapsed / throtl_slice;
|
|
|
|
if (!nr_slices)
|
|
return;
|
|
tmp = tg->bps[rw] * throtl_slice * nr_slices;
|
|
do_div(tmp, HZ);
|
|
bytes_trim = tmp;
|
|
|
|
io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
|
|
|
|
if (!bytes_trim && !io_trim)
|
|
return;
|
|
|
|
if (tg->bytes_disp[rw] >= bytes_trim)
|
|
tg->bytes_disp[rw] -= bytes_trim;
|
|
else
|
|
tg->bytes_disp[rw] = 0;
|
|
|
|
if (tg->io_disp[rw] >= io_trim)
|
|
tg->io_disp[rw] -= io_trim;
|
|
else
|
|
tg->io_disp[rw] = 0;
|
|
|
|
tg->slice_start[rw] += nr_slices * throtl_slice;
|
|
|
|
throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"
|
|
" start=%lu end=%lu jiffies=%lu",
|
|
rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
|
|
tg->slice_start[rw], tg->slice_end[rw], jiffies);
|
|
}
|
|
|
|
static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg,
|
|
struct bio *bio, unsigned long *wait)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
unsigned int io_allowed;
|
|
unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
|
|
u64 tmp;
|
|
|
|
jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
|
|
|
|
/* Slice has just started. Consider one slice interval */
|
|
if (!jiffy_elapsed)
|
|
jiffy_elapsed_rnd = throtl_slice;
|
|
|
|
jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
|
|
|
|
/*
|
|
* jiffy_elapsed_rnd should not be a big value as minimum iops can be
|
|
* 1 then at max jiffy elapsed should be equivalent of 1 second as we
|
|
* will allow dispatch after 1 second and after that slice should
|
|
* have been trimmed.
|
|
*/
|
|
|
|
tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd;
|
|
do_div(tmp, HZ);
|
|
|
|
if (tmp > UINT_MAX)
|
|
io_allowed = UINT_MAX;
|
|
else
|
|
io_allowed = tmp;
|
|
|
|
if (tg->io_disp[rw] + 1 <= io_allowed) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return 1;
|
|
}
|
|
|
|
/* Calc approx time to dispatch */
|
|
jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1;
|
|
|
|
if (jiffy_wait > jiffy_elapsed)
|
|
jiffy_wait = jiffy_wait - jiffy_elapsed;
|
|
else
|
|
jiffy_wait = 1;
|
|
|
|
if (wait)
|
|
*wait = jiffy_wait;
|
|
return 0;
|
|
}
|
|
|
|
static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg,
|
|
struct bio *bio, unsigned long *wait)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
u64 bytes_allowed, extra_bytes, tmp;
|
|
unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
|
|
|
|
jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
|
|
|
|
/* Slice has just started. Consider one slice interval */
|
|
if (!jiffy_elapsed)
|
|
jiffy_elapsed_rnd = throtl_slice;
|
|
|
|
jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
|
|
|
|
tmp = tg->bps[rw] * jiffy_elapsed_rnd;
|
|
do_div(tmp, HZ);
|
|
bytes_allowed = tmp;
|
|
|
|
if (tg->bytes_disp[rw] + bio->bi_size <= bytes_allowed) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return 1;
|
|
}
|
|
|
|
/* Calc approx time to dispatch */
|
|
extra_bytes = tg->bytes_disp[rw] + bio->bi_size - bytes_allowed;
|
|
jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]);
|
|
|
|
if (!jiffy_wait)
|
|
jiffy_wait = 1;
|
|
|
|
/*
|
|
* This wait time is without taking into consideration the rounding
|
|
* up we did. Add that time also.
|
|
*/
|
|
jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed);
|
|
if (wait)
|
|
*wait = jiffy_wait;
|
|
return 0;
|
|
}
|
|
|
|
static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) {
|
|
if (tg->bps[rw] == -1 && tg->iops[rw] == -1)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Returns whether one can dispatch a bio or not. Also returns approx number
|
|
* of jiffies to wait before this bio is with-in IO rate and can be dispatched
|
|
*/
|
|
static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
|
|
struct bio *bio, unsigned long *wait)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
|
|
|
|
/*
|
|
* Currently whole state machine of group depends on first bio
|
|
* queued in the group bio list. So one should not be calling
|
|
* this function with a different bio if there are other bios
|
|
* queued.
|
|
*/
|
|
BUG_ON(tg->nr_queued[rw] && bio != bio_list_peek(&tg->bio_lists[rw]));
|
|
|
|
/* If tg->bps = -1, then BW is unlimited */
|
|
if (tg->bps[rw] == -1 && tg->iops[rw] == -1) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* If previous slice expired, start a new one otherwise renew/extend
|
|
* existing slice to make sure it is at least throtl_slice interval
|
|
* long since now.
|
|
*/
|
|
if (throtl_slice_used(td, tg, rw))
|
|
throtl_start_new_slice(td, tg, rw);
|
|
else {
|
|
if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
|
|
throtl_extend_slice(td, tg, rw, jiffies + throtl_slice);
|
|
}
|
|
|
|
if (tg_with_in_bps_limit(td, tg, bio, &bps_wait)
|
|
&& tg_with_in_iops_limit(td, tg, bio, &iops_wait)) {
|
|
if (wait)
|
|
*wait = 0;
|
|
return 1;
|
|
}
|
|
|
|
max_wait = max(bps_wait, iops_wait);
|
|
|
|
if (wait)
|
|
*wait = max_wait;
|
|
|
|
if (time_before(tg->slice_end[rw], jiffies + max_wait))
|
|
throtl_extend_slice(td, tg, rw, jiffies + max_wait);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
|
|
{
|
|
bool rw = bio_data_dir(bio);
|
|
bool sync = rw_is_sync(bio->bi_rw);
|
|
|
|
/* Charge the bio to the group */
|
|
tg->bytes_disp[rw] += bio->bi_size;
|
|
tg->io_disp[rw]++;
|
|
|
|
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 (!td->limits_changed)
|
|
return;
|
|
|
|
xchg(&td->limits_changed, false);
|
|
|
|
throtl_log(td, "limits changed");
|
|
|
|
hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
|
|
if (!tg->limits_changed)
|
|
continue;
|
|
|
|
if (!xchg(&tg->limits_changed, false))
|
|
continue;
|
|
|
|
throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu"
|
|
" riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE],
|
|
tg->iops[READ], tg->iops[WRITE]);
|
|
|
|
/*
|
|
* Restart the slices for both READ and WRITES. It
|
|
* might happen that a group's limit are dropped
|
|
* suddenly and we don't want to account recently
|
|
* dispatched IO with new low rate
|
|
*/
|
|
throtl_start_new_slice(td, tg, 0);
|
|
throtl_start_new_slice(td, tg, 1);
|
|
|
|
if (throtl_tg_on_rr(tg))
|
|
tg_update_disptime(td, tg);
|
|
}
|
|
}
|
|
|
|
/* Dispatch throttled bios. Should be called without queue lock held. */
|
|
static int throtl_dispatch(struct request_queue *q)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
unsigned int nr_disp = 0;
|
|
struct bio_list bio_list_on_stack;
|
|
struct bio *bio;
|
|
struct blk_plug plug;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
throtl_process_limit_change(td);
|
|
|
|
if (!total_nr_queued(td))
|
|
goto out;
|
|
|
|
bio_list_init(&bio_list_on_stack);
|
|
|
|
throtl_log(td, "dispatch nr_queued=%u read=%u write=%u",
|
|
total_nr_queued(td), td->nr_queued[READ],
|
|
td->nr_queued[WRITE]);
|
|
|
|
nr_disp = throtl_select_dispatch(td, &bio_list_on_stack);
|
|
|
|
if (nr_disp)
|
|
throtl_log(td, "bios disp=%u", nr_disp);
|
|
|
|
throtl_schedule_next_dispatch(td);
|
|
out:
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
/*
|
|
* If we dispatched some requests, unplug the queue to make sure
|
|
* immediate dispatch
|
|
*/
|
|
if (nr_disp) {
|
|
blk_start_plug(&plug);
|
|
while((bio = bio_list_pop(&bio_list_on_stack)))
|
|
generic_make_request(bio);
|
|
blk_finish_plug(&plug);
|
|
}
|
|
return nr_disp;
|
|
}
|
|
|
|
void blk_throtl_work(struct work_struct *work)
|
|
{
|
|
struct throtl_data *td = container_of(work, struct throtl_data,
|
|
throtl_work.work);
|
|
struct request_queue *q = td->queue;
|
|
|
|
throtl_dispatch(q);
|
|
}
|
|
|
|
/* Call with queue lock held */
|
|
static void
|
|
throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay)
|
|
{
|
|
|
|
struct delayed_work *dwork = &td->throtl_work;
|
|
|
|
/* schedule work if limits changed even if no bio is queued */
|
|
if (total_nr_queued(td) || td->limits_changed) {
|
|
/*
|
|
* We might have a work scheduled to be executed in future.
|
|
* Cancel that and schedule a new one.
|
|
*/
|
|
__cancel_delayed_work(dwork);
|
|
queue_delayed_work(kthrotld_workqueue, dwork, delay);
|
|
throtl_log(td, "schedule work. delay=%lu jiffies=%lu",
|
|
delay, jiffies);
|
|
}
|
|
}
|
|
|
|
static 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 bool throtl_release_tgs(struct throtl_data *td, bool release_root)
|
|
{
|
|
struct hlist_node *pos, *n;
|
|
struct throtl_grp *tg;
|
|
bool empty = true;
|
|
|
|
hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
|
|
/* skip root? */
|
|
if (!release_root && tg == td->root_tg)
|
|
continue;
|
|
|
|
/*
|
|
* 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);
|
|
else
|
|
empty = false;
|
|
}
|
|
return empty;
|
|
}
|
|
|
|
/*
|
|
* 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(). @q is the rcu protected
|
|
* pointer. That means @q is a valid request_queue pointer as long as we
|
|
* are rcu read lock.
|
|
*
|
|
* @q 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(struct request_queue *q,
|
|
struct blkio_group *blkg)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
throtl_destroy_tg(q->td, tg_of_blkg(blkg));
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
|
|
static bool throtl_clear_queue(struct request_queue *q)
|
|
{
|
|
lockdep_assert_held(q->queue_lock);
|
|
|
|
/*
|
|
* Clear tgs but leave the root one alone. This is necessary
|
|
* because root_tg is expected to be persistent and safe because
|
|
* blk-throtl can never be disabled while @q is alive. This is a
|
|
* kludge to prepare for unified blkg. This whole function will be
|
|
* removed soon.
|
|
*/
|
|
return throtl_release_tgs(q->td, false);
|
|
}
|
|
|
|
static void throtl_update_blkio_group_common(struct throtl_data *td,
|
|
struct throtl_grp *tg)
|
|
{
|
|
xchg(&tg->limits_changed, true);
|
|
xchg(&td->limits_changed, true);
|
|
/* Schedule a work now to process the limit change */
|
|
throtl_schedule_delayed_work(td, 0);
|
|
}
|
|
|
|
/*
|
|
* For all update functions, @q should be a valid pointer because these
|
|
* update functions are called under blkcg_lock, that means, blkg is
|
|
* valid and in turn @q is valid. queue exit path can not race because
|
|
* 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(struct request_queue *q,
|
|
struct blkio_group *blkg, u64 read_bps)
|
|
{
|
|
struct throtl_grp *tg = tg_of_blkg(blkg);
|
|
|
|
tg->bps[READ] = read_bps;
|
|
throtl_update_blkio_group_common(q->td, tg);
|
|
}
|
|
|
|
static void throtl_update_blkio_group_write_bps(struct request_queue *q,
|
|
struct blkio_group *blkg, u64 write_bps)
|
|
{
|
|
struct throtl_grp *tg = tg_of_blkg(blkg);
|
|
|
|
tg->bps[WRITE] = write_bps;
|
|
throtl_update_blkio_group_common(q->td, tg);
|
|
}
|
|
|
|
static void throtl_update_blkio_group_read_iops(struct request_queue *q,
|
|
struct blkio_group *blkg, unsigned int read_iops)
|
|
{
|
|
struct throtl_grp *tg = tg_of_blkg(blkg);
|
|
|
|
tg->iops[READ] = read_iops;
|
|
throtl_update_blkio_group_common(q->td, tg);
|
|
}
|
|
|
|
static void throtl_update_blkio_group_write_iops(struct request_queue *q,
|
|
struct blkio_group *blkg, unsigned int write_iops)
|
|
{
|
|
struct throtl_grp *tg = tg_of_blkg(blkg);
|
|
|
|
tg->iops[WRITE] = write_iops;
|
|
throtl_update_blkio_group_common(q->td, tg);
|
|
}
|
|
|
|
static void throtl_shutdown_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_alloc_group_fn = throtl_alloc_blkio_group,
|
|
.blkio_link_group_fn = throtl_link_blkio_group,
|
|
.blkio_unlink_group_fn = throtl_unlink_blkio_group,
|
|
.blkio_clear_queue_fn = throtl_clear_queue,
|
|
.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,
|
|
};
|
|
|
|
bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
struct throtl_grp *tg;
|
|
bool rw = bio_data_dir(bio), update_disptime = true;
|
|
struct blkio_cgroup *blkcg;
|
|
bool throttled = false;
|
|
|
|
if (bio->bi_rw & REQ_THROTTLED) {
|
|
bio->bi_rw &= ~REQ_THROTTLED;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* A throtl_grp pointer retrieved under rcu can be used to access
|
|
* basic fields like stats and io rates. If a group has no rules,
|
|
* just update the dispatch stats in lockless manner and return.
|
|
*/
|
|
rcu_read_lock();
|
|
blkcg = task_blkio_cgroup(current);
|
|
tg = throtl_lookup_tg(td, blkcg);
|
|
if (tg) {
|
|
if (tg_no_rule_group(tg, rw)) {
|
|
blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size,
|
|
rw, rw_is_sync(bio->bi_rw));
|
|
goto out_unlock_rcu;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Either group has not been allocated yet or it is not an unlimited
|
|
* IO group
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
tg = throtl_lookup_create_tg(td, blkcg);
|
|
if (unlikely(!tg))
|
|
goto out_unlock;
|
|
|
|
if (tg->nr_queued[rw]) {
|
|
/*
|
|
* There is already another bio queued in same dir. No
|
|
* need to update dispatch time.
|
|
*/
|
|
update_disptime = false;
|
|
goto queue_bio;
|
|
|
|
}
|
|
|
|
/* Bio is with-in rate limit of group */
|
|
if (tg_may_dispatch(td, tg, bio, NULL)) {
|
|
throtl_charge_bio(tg, bio);
|
|
|
|
/*
|
|
* We need to trim slice even when bios are not being queued
|
|
* otherwise it might happen that a bio is not queued for
|
|
* a long time and slice keeps on extending and trim is not
|
|
* called for a long time. Now if limits are reduced suddenly
|
|
* we take into account all the IO dispatched so far at new
|
|
* low rate and * newly queued IO gets a really long dispatch
|
|
* time.
|
|
*
|
|
* So keep on trimming slice even if bio is not queued.
|
|
*/
|
|
throtl_trim_slice(td, tg, rw);
|
|
goto out_unlock;
|
|
}
|
|
|
|
queue_bio:
|
|
throtl_log_tg(td, tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu"
|
|
" iodisp=%u iops=%u queued=%d/%d",
|
|
rw == READ ? 'R' : 'W',
|
|
tg->bytes_disp[rw], bio->bi_size, tg->bps[rw],
|
|
tg->io_disp[rw], tg->iops[rw],
|
|
tg->nr_queued[READ], tg->nr_queued[WRITE]);
|
|
|
|
throtl_add_bio_tg(q->td, tg, bio);
|
|
throttled = true;
|
|
|
|
if (update_disptime) {
|
|
tg_update_disptime(td, tg);
|
|
throtl_schedule_next_dispatch(td);
|
|
}
|
|
|
|
out_unlock:
|
|
spin_unlock_irq(q->queue_lock);
|
|
out_unlock_rcu:
|
|
rcu_read_unlock();
|
|
out:
|
|
return throttled;
|
|
}
|
|
|
|
/**
|
|
* blk_throtl_drain - drain throttled bios
|
|
* @q: request_queue to drain throttled bios for
|
|
*
|
|
* Dispatch all currently throttled bios on @q through ->make_request_fn().
|
|
*/
|
|
void blk_throtl_drain(struct request_queue *q)
|
|
__releases(q->queue_lock) __acquires(q->queue_lock)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
struct throtl_rb_root *st = &td->tg_service_tree;
|
|
struct throtl_grp *tg;
|
|
struct bio_list bl;
|
|
struct bio *bio;
|
|
|
|
WARN_ON_ONCE(!queue_is_locked(q));
|
|
|
|
bio_list_init(&bl);
|
|
|
|
while ((tg = throtl_rb_first(st))) {
|
|
throtl_dequeue_tg(td, tg);
|
|
|
|
while ((bio = bio_list_peek(&tg->bio_lists[READ])))
|
|
tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
|
|
while ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
|
|
tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
|
|
}
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
while ((bio = bio_list_pop(&bl)))
|
|
generic_make_request(bio);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
}
|
|
|
|
int blk_throtl_init(struct request_queue *q)
|
|
{
|
|
struct throtl_data *td;
|
|
struct blkio_group *blkg;
|
|
|
|
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;
|
|
td->limits_changed = false;
|
|
INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
|
|
|
|
q->td = td;
|
|
td->queue = q;
|
|
|
|
/* alloc and init root group. */
|
|
rcu_read_lock();
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
blkg = blkg_lookup_create(&blkio_root_cgroup, q, BLKIO_POLICY_THROTL,
|
|
true);
|
|
if (!IS_ERR(blkg))
|
|
td->root_tg = tg_of_blkg(blkg);
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
rcu_read_unlock();
|
|
|
|
if (!td->root_tg) {
|
|
kfree(td);
|
|
return -ENOMEM;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void blk_throtl_exit(struct request_queue *q)
|
|
{
|
|
struct throtl_data *td = q->td;
|
|
bool wait = false;
|
|
|
|
BUG_ON(!td);
|
|
|
|
throtl_shutdown_wq(q);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
throtl_release_tgs(td, true);
|
|
|
|
/* If there are other groups */
|
|
if (td->nr_undestroyed_grps > 0)
|
|
wait = true;
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
/*
|
|
* Wait for tg->blkg->q 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_wq(q);
|
|
}
|
|
|
|
void blk_throtl_release(struct request_queue *q)
|
|
{
|
|
kfree(q->td);
|
|
}
|
|
|
|
static int __init throtl_init(void)
|
|
{
|
|
kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
|
|
if (!kthrotld_workqueue)
|
|
panic("Failed to create kthrotld\n");
|
|
|
|
blkio_policy_register(&blkio_policy_throtl);
|
|
return 0;
|
|
}
|
|
|
|
module_init(throtl_init);
|