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| author | Valentin Schneider <valentin.schneider@arm.com> | 2018-09-26 16:12:07 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-11-04 00:59:23 +0100 |
| commit | 3f130a37c442d5c4d66531b240ebe9abfef426b5 (patch) | |
| tree | 072f5b007157a6100c6540318875321d6e42480e /kernel/sched | |
| parent | 47b7aee14fd7e453370a5d15dfb11c958ca360f2 (diff) | |
| download | linux-3f130a37c442d5c4d66531b240ebe9abfef426b5.tar.gz linux-3f130a37c442d5c4d66531b240ebe9abfef426b5.tar.bz2 linux-3f130a37c442d5c4d66531b240ebe9abfef426b5.zip | |
sched/fair: Don't increase sd->balance_interval on newidle balance
When load_balance() fails to move some load because of task affinity,
we end up increasing sd->balance_interval to delay the next periodic
balance in the hopes that next time we look, that annoying pinned
task(s) will be gone.
However, idle_balance() pays no attention to sd->balance_interval, yet
it will still lead to an increase in balance_interval in case of
pinned tasks.
If we're going through several newidle balances (e.g. we have a
periodic task), this can lead to a huge increase of the
balance_interval in a very small amount of time.
To prevent that, don't increase the balance interval when going
through a newidle balance.
This is a similar approach to what is done in commit 58b26c4c0257
("sched: Increment cache_nice_tries only on periodic lb"), where we
disregard newidle balance and rely on periodic balance for more stable
results.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: patrick.bellasi@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1537974727-30788-2-git-send-email-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/fair.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4e298931a715..a17ca4254427 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8876,13 +8876,22 @@ out_all_pinned: sd->nr_balance_failed = 0; out_one_pinned: + ld_moved = 0; + + /* + * idle_balance() disregards balance intervals, so we could repeatedly + * reach this code, which would lead to balance_interval skyrocketting + * in a short amount of time. Skip the balance_interval increase logic + * to avoid that. + */ + if (env.idle == CPU_NEWLY_IDLE) + goto out; + /* tune up the balancing interval */ if ((env.flags & LBF_ALL_PINNED && sd->balance_interval < MAX_PINNED_INTERVAL) || sd->balance_interval < sd->max_interval) sd->balance_interval *= 2; - - ld_moved = 0; out: return ld_moved; } |