Last patch introduces a way to detect idle cgroup. We use it to make
upgrade/downgrade decision. And the new algorithm can detect completely
idle cgroup too, so we can delete the corresponding code.
Signed-off-by: Shaohua Li <s...@fb.com>
---
block/blk-throttle.c | 39 +++++++++++++++++++++++++--------------
1 file changed, 25 insertions(+), 14 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index e403e88..01b494d 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -146,8 +146,7 @@ struct throtl_grp {
unsigned long last_check_time;
- unsigned long last_dispatch_time[2];
-
+ int upgrade_check_batch;
/* When did we start a new slice */
unsigned long slice_start[2];
unsigned long slice_end[2];
@@ -487,8 +486,6 @@ static void throtl_pd_online(struct blkg_policy_data *pd)
* Update has_rules[] after a new group is brought online.
*/
tg_update_has_rules(tg);
- tg->last_dispatch_time[READ] = jiffies;
- tg->last_dispatch_time[WRITE] = jiffies;
}
static void blk_throtl_update_valid_limit(struct throtl_data *td)
@@ -1667,9 +1664,8 @@ static bool throtl_upgrade_check_one(struct throtl_grp
*tg)
return true;
if (time_after_eq(jiffies,
- tg->last_dispatch_time[READ] + tg->td->throtl_slice) &&
- time_after_eq(jiffies,
- tg->last_dispatch_time[WRITE] + tg->td->throtl_slice))
+ tg_last_high_overflow_time(tg) + tg->td->throtl_slice) &&
+ throtl_tg_is_idle(tg))
return true;
return false;
}
@@ -1718,6 +1714,24 @@ static bool throtl_can_upgrade(struct throtl_data *td,
return true;
}
+static void throtl_upgrade_check(struct throtl_grp *tg)
+{
+ if (tg->td->limit_index != LIMIT_HIGH)
+ return;
+
+ if (!time_after_eq(jiffies,
+ __tg_last_high_overflow_time(tg) + tg->td->throtl_slice))
+ return;
+
+ tg->upgrade_check_batch++;
+ if (tg->upgrade_check_batch < 16)
+ return;
+ tg->upgrade_check_batch = 0;
+
+ if (throtl_can_upgrade(tg->td, NULL))
+ throtl_upgrade_state(tg->td);
+}
+
static void throtl_upgrade_state(struct throtl_data *td)
{
struct cgroup_subsys_state *pos_css;
@@ -1752,18 +1766,15 @@ static bool throtl_downgrade_check_one(struct
throtl_grp *tg)
struct throtl_data *td = tg->td;
unsigned long now = jiffies;
- if (time_after_eq(now, tg->last_dispatch_time[READ] +
- td->throtl_slice) &&
- time_after_eq(now, tg->last_dispatch_time[WRITE] +
- td->throtl_slice))
- return false;
/*
* If cgroup is below high limit, consider downgrade and throttle other
* cgroups
*/
if (time_after_eq(now, td->high_upgrade_time + td->throtl_slice) &&
time_after_eq(now, tg_last_high_overflow_time(tg) +
- td->throtl_slice))
+ td->throtl_slice) &&
+ (!throtl_tg_is_idle(tg) ||
+ !list_empty(&tg_to_blkg(tg)->blkcg->css.children)))
return true;
return false;
}
@@ -1902,10 +1913,10 @@ bool blk_throtl_bio(struct request_queue *q, struct
blkcg_gq *blkg,
again:
while (true) {
- tg->last_dispatch_time[rw] = jiffies;
if (tg->last_high_overflow_time[rw] == 0)
tg->last_high_overflow_time[rw] = jiffies;
throtl_downgrade_check(tg);
+ throtl_upgrade_check(tg);
/* throtl is FIFO - if bios are already queued, should queue */
if (sq->nr_queued[rw])
break;
--
2.9.3
--
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