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blk-throttle: add hierarchy support for latency target and idle time
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For idle time, children's setting should not be bigger than parent's.
For latency target, children's setting should not be smaller than
parent's. The leaf nodes will adjust their settings according to the
hierarchy and compare their IO with the settings and do
upgrade/downgrade. parents nodes don't need to track their IO
latency/idle time.

Signed-off-by: Shaohua Li <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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@shligit @axboe
shligit authored and axboe committed May 22, 2017
1 parent 0833289 commit 5b81fc3
Showing 1 changed file with 36 additions and 14 deletions.
50 changes: 36 additions & 14 deletions block/blk-throttle.c
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Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,7 @@ struct throtl_grp {
unsigned long last_check_time;

unsigned long latency_target; /* us */
unsigned long latency_target_conf; /* us */
/* When did we start a new slice */
unsigned long slice_start[2];
unsigned long slice_end[2];
Expand All @@ -165,6 +166,7 @@ struct throtl_grp {
unsigned long checked_last_finish_time; /* ns / 1024 */
unsigned long avg_idletime; /* ns / 1024 */
unsigned long idletime_threshold; /* us */
unsigned long idletime_threshold_conf; /* us */

unsigned int bio_cnt; /* total bios */
unsigned int bad_bio_cnt; /* bios exceeding latency threshold */
Expand Down Expand Up @@ -482,6 +484,7 @@ static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node)
/* LIMIT_LOW will have default value 0 */

tg->latency_target = DFL_LATENCY_TARGET;
tg->latency_target_conf = DFL_LATENCY_TARGET;

return &tg->pd;
}
Expand Down Expand Up @@ -512,6 +515,7 @@ static void throtl_pd_init(struct blkg_policy_data *pd)
tg->td = td;

tg->idletime_threshold = td->dft_idletime_threshold;
tg->idletime_threshold_conf = td->dft_idletime_threshold;
}

/*
Expand Down Expand Up @@ -1367,8 +1371,25 @@ static void tg_conf_updated(struct throtl_grp *tg)
* restrictions in the whole hierarchy and allows them to bypass
* blk-throttle.
*/
blkg_for_each_descendant_pre(blkg, pos_css, tg_to_blkg(tg))
tg_update_has_rules(blkg_to_tg(blkg));
blkg_for_each_descendant_pre(blkg, pos_css, tg_to_blkg(tg)) {
struct throtl_grp *this_tg = blkg_to_tg(blkg);
struct throtl_grp *parent_tg;

tg_update_has_rules(this_tg);
/* ignore root/second level */
if (!cgroup_subsys_on_dfl(io_cgrp_subsys) || !blkg->parent ||
!blkg->parent->parent)
continue;
parent_tg = blkg_to_tg(blkg->parent);
/*
* make sure all children has lower idle time threshold and
* higher latency target
*/
this_tg->idletime_threshold = min(this_tg->idletime_threshold,
parent_tg->idletime_threshold);
this_tg->latency_target = max(this_tg->latency_target,
parent_tg->latency_target);
}

/*
* We're already holding queue_lock and know @tg is valid. Let's
Expand Down Expand Up @@ -1497,8 +1518,8 @@ static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd,
tg->iops_conf[READ][off] == iops_dft &&
tg->iops_conf[WRITE][off] == iops_dft &&
(off != LIMIT_LOW ||
(tg->idletime_threshold == tg->td->dft_idletime_threshold &&
tg->latency_target == DFL_LATENCY_TARGET)))
(tg->idletime_threshold_conf == tg->td->dft_idletime_threshold &&
tg->latency_target_conf == DFL_LATENCY_TARGET)))
return 0;

if (tg->bps_conf[READ][off] != bps_dft)
Expand All @@ -1514,17 +1535,17 @@ static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd,
snprintf(bufs[3], sizeof(bufs[3]), "%u",
tg->iops_conf[WRITE][off]);
if (off == LIMIT_LOW) {
if (tg->idletime_threshold == ULONG_MAX)
if (tg->idletime_threshold_conf == ULONG_MAX)
strcpy(idle_time, " idle=max");
else
snprintf(idle_time, sizeof(idle_time), " idle=%lu",
tg->idletime_threshold);
tg->idletime_threshold_conf);

if (tg->latency_target == ULONG_MAX)
if (tg->latency_target_conf == ULONG_MAX)
strcpy(latency_time, " latency=max");
else
snprintf(latency_time, sizeof(latency_time),
" latency=%lu", tg->latency_target);
" latency=%lu", tg->latency_target_conf);
}

seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s%s%s\n",
Expand Down Expand Up @@ -1563,8 +1584,8 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of,
v[2] = tg->iops_conf[READ][index];
v[3] = tg->iops_conf[WRITE][index];

idle_time = tg->idletime_threshold;
latency_time = tg->latency_target;
idle_time = tg->idletime_threshold_conf;
latency_time = tg->latency_target_conf;
while (true) {
char tok[27]; /* wiops=18446744073709551616 */
char *p;
Expand Down Expand Up @@ -1628,10 +1649,10 @@ static ssize_t tg_set_limit(struct kernfs_open_file *of,
blk_throtl_update_limit_valid(tg->td);
if (tg->td->limit_valid[LIMIT_LOW])
tg->td->limit_index = LIMIT_LOW;
tg->idletime_threshold = (idle_time == ULONG_MAX) ?
ULONG_MAX : idle_time;
tg->latency_target = (latency_time == ULONG_MAX) ?
ULONG_MAX : latency_time;
tg->idletime_threshold_conf = idle_time;
tg->idletime_threshold = tg->idletime_threshold_conf;
tg->latency_target_conf = latency_time;
tg->latency_target = tg->latency_target_conf;
}
tg_conf_updated(tg);
ret = 0;
Expand Down Expand Up @@ -2385,6 +2406,7 @@ void blk_throtl_register_queue(struct request_queue *q)
struct throtl_grp *tg = blkg_to_tg(blkg);

tg->idletime_threshold = td->dft_idletime_threshold;
tg->idletime_threshold_conf = td->dft_idletime_threshold;
}
rcu_read_unlock();
}
Expand Down

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