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Commit 8e89d13f authored by Vivek Goyal's avatar Vivek Goyal Committed by Jens Axboe
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blkio: Implementation of IOPS limit logic 

o core logic of implementing IOPS throttling.
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 7702e8f4
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Showing with 127 additions and 37 deletions
block/blk-throttle.c
View file @ 8e89d13f
......@@ -59,8 +59,13 @@ struct throtl_grp {
/* 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];
......@@ -194,6 +199,8 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td,
tg->bps[READ] = blkcg_get_read_bps(blkcg, tg->blkg.dev);
tg->bps[WRITE] = blkcg_get_write_bps(blkcg, tg->blkg.dev);
tg->iops[READ] = blkcg_get_read_iops(blkcg, tg->blkg.dev);
tg->iops[WRITE] = blkcg_get_write_iops(blkcg, tg->blkg.dev);
hlist_add_head(&tg->tg_node, &td->tg_list);
td->nr_undestroyed_grps++;
......@@ -335,6 +342,7 @@ 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",
......@@ -365,7 +373,7 @@ throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw)
static inline void
throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
{
unsigned long nr_slices, bytes_trim, time_elapsed;
unsigned long nr_slices, bytes_trim, time_elapsed, io_trim;
BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
......@@ -385,8 +393,9 @@ throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
return;
bytes_trim = (tg->bps[rw] * throtl_slice * nr_slices)/HZ;
io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
if (!bytes_trim)
if (!bytes_trim && !io_trim)
return;
if (tg->bytes_disp[rw] >= bytes_trim)
......@@ -394,51 +403,62 @@ throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
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=%lu"
throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%lu io=%lu"
" start=%lu end=%lu jiffies=%lu",
rw == READ ? 'R' : 'W', nr_slices, bytes_trim,
rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_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)
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);
u64 bytes_allowed, extra_bytes;
unsigned int io_allowed;
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]));
jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
/* If tg->bps = -1, then BW is unlimited */
if (tg->bps[rw] == -1) {
/* 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);
io_allowed = (tg->iops[rw] * jiffies_to_msecs(jiffy_elapsed_rnd))
/ MSEC_PER_SEC;
if (tg->io_disp[rw] + 1 <= io_allowed) {
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);
}
/* 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;
unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
......@@ -469,12 +489,62 @@ static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
* 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 (time_before(tg->slice_end[rw], jiffies + jiffy_wait))
throtl_extend_slice(td, tg, rw, jiffies + jiffy_wait);
/* 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;
}
......@@ -486,13 +556,13 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
/* 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,
......@@ -763,6 +833,18 @@ static void throtl_update_blkio_group_write_bps (struct blkio_group *blkg,
tg_of_blkg(blkg)->bps[WRITE] = write_bps;
}
static void throtl_update_blkio_group_read_iops (struct blkio_group *blkg,
unsigned int read_iops)
{
tg_of_blkg(blkg)->iops[READ] = read_iops;
}
static void throtl_update_blkio_group_write_iops (struct blkio_group *blkg,
unsigned int write_iops)
{
tg_of_blkg(blkg)->iops[WRITE] = write_iops;
}
void throtl_shutdown_timer_wq(struct request_queue *q)
{
struct throtl_data *td = q->td;
......@@ -777,7 +859,12 @@ static struct blkio_policy_type blkio_policy_throtl = {
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)
......@@ -811,9 +898,11 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop)
}
queue_bio:
throtl_log_tg(td, tg, "[%c] bio. disp=%u sz=%u bps=%llu"
" queued=%d/%d", rw == READ ? 'R' : 'W',
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);
......@@ -850,6 +939,7 @@ int blk_throtl_init(struct request_queue *q)
/* Practically unlimited BW */
tg->bps[0] = tg->bps[1] = -1;
tg->iops[0] = tg->iops[1] = -1;
atomic_set(&tg->ref, 1);
INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
......
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