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authorJosh Don <joshdon@google.com>2020-04-11 01:52:08 +0300
committerPeter Zijlstra <peterz@infradead.org>2020-04-30 21:14:38 +0300
commitab93a4bc955b3980c699430bc0b633f0d8b607be (patch)
tree06c7c6724eb51685931e630d70f5e3663914d428 /kernel/sched
parente98fa02c4f2ea4991dae422ac7e34d102d2f0599 (diff)
downloadlinux-ab93a4bc955b3980c699430bc0b633f0d8b607be.tar.xz
sched/fair: Remove distribute_running from CFS bandwidth
This is mostly a revert of commit: baa9be4ffb55 ("sched/fair: Fix throttle_list starvation with low CFS quota") The primary use of distribute_running was to determine whether to add throttled entities to the head or the tail of the throttled list. Now that we always add to the tail, we can remove this field. The other use of distribute_running is in the slack_timer, so that we don't start a distribution while one is already running. However, even in the event that this race occurs, it is fine to have two distributions running (especially now that distribute grabs the cfs_b->lock to determine remaining quota before assigning). Signed-off-by: Josh Don <joshdon@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Phil Auld <pauld@redhat.com> Tested-by: Phil Auld <pauld@redhat.com> Link: https://lkml.kernel.org/r/20200410225208.109717-3-joshdon@google.com
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c13
-rw-r--r--kernel/sched/sched.h1
2 files changed, 1 insertions, 13 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0c13a41bde81..3d6ce751abb6 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4931,14 +4931,12 @@ static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun, u
/*
* This check is repeated as we release cfs_b->lock while we unthrottle.
*/
- while (throttled && cfs_b->runtime > 0 && !cfs_b->distribute_running) {
- cfs_b->distribute_running = 1;
+ while (throttled && cfs_b->runtime > 0) {
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
/* we can't nest cfs_b->lock while distributing bandwidth */
distribute_cfs_runtime(cfs_b);
raw_spin_lock_irqsave(&cfs_b->lock, flags);
- cfs_b->distribute_running = 0;
throttled = !list_empty(&cfs_b->throttled_cfs_rq);
}
@@ -5052,10 +5050,6 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
/* confirm we're still not at a refresh boundary */
raw_spin_lock_irqsave(&cfs_b->lock, flags);
cfs_b->slack_started = false;
- if (cfs_b->distribute_running) {
- raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
- return;
- }
if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
@@ -5065,9 +5059,6 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice)
runtime = cfs_b->runtime;
- if (runtime)
- cfs_b->distribute_running = 1;
-
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
if (!runtime)
@@ -5076,7 +5067,6 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
distribute_cfs_runtime(cfs_b);
raw_spin_lock_irqsave(&cfs_b->lock, flags);
- cfs_b->distribute_running = 0;
raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
}
@@ -5218,7 +5208,6 @@ void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
cfs_b->period_timer.function = sched_cfs_period_timer;
hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
cfs_b->slack_timer.function = sched_cfs_slack_timer;
- cfs_b->distribute_running = 0;
cfs_b->slack_started = false;
}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index db3a57675ccf..7198683b2869 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -349,7 +349,6 @@ struct cfs_bandwidth {
u8 idle;
u8 period_active;
- u8 distribute_running;
u8 slack_started;
struct hrtimer period_timer;
struct hrtimer slack_timer;