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sched/fair: Rewrite cfs_rq->removed_*avg

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Since on wakeup migration we don't hold the rq->lock for the old CPU
we cannot update its state. Instead we add the removed 'load' to an
atomic variable and have the next update on that CPU collect and
process it.

Currently we have 2 atomic variables; which already have the issue
that they can be read out-of-sync. Also, two atomic ops on a single
cacheline is already more expensive than an uncontended lock.

Since we want to add more, convert the thing over to an explicit
cacheline with a lock in.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
2017-05-08 16:51:41 +02:00
committed by Ingo Molnar
parent 9059393e4e
commit 2a2f5d4e44
3 changed files with 48 additions and 24 deletions
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13
kernel/sched/sched.h
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@ -445,14 +445,19 @@ struct cfs_rq {
struct sched_avg avg;
u64 runnable_load_sum;
unsigned long runnable_load_avg;
#ifndef CONFIG_64BIT
u64 load_last_update_time_copy;
#endif
#ifdef CONFIG_FAIR_GROUP_SCHED
unsigned long tg_load_avg_contrib;
unsigned long propagate_avg;
#endif
atomic_long_t removed_load_avg, removed_util_avg;
#ifndef CONFIG_64BIT
u64 load_last_update_time_copy;
#endif
struct {
raw_spinlock_t lock ____cacheline_aligned;
int nr;
unsigned long load_avg;
unsigned long util_avg;
} removed;
#ifdef CONFIG_FAIR_GROUP_SCHED
/*