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| author | Joonsoo Kim <iamjoonsoo.kim@lge.com> | 2013-09-10 15:54:49 +0900 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-09-10 09:20:42 +0200 |
| commit | b0cff9d88ce2f3030f73138078c5b1019f17e1cc (patch) | |
| tree | c99ab79be7b17494f22a66207bfc19e572a3dc17 /kernel | |
| parent | 816434ec4a674fcdb3c2221a6dffdc8f34020550 (diff) | |
| download | lwn-b0cff9d88ce2f3030f73138078c5b1019f17e1cc.tar.gz lwn-b0cff9d88ce2f3030f73138078c5b1019f17e1cc.zip | |
sched: Fix load balancing performance regression in should_we_balance()
Commit 23f0d20 ("sched: Factor out code to should_we_balance()")
introduces the should_we_balance() function. This function should
return 1 if this cpu is appropriate for balancing. But the newly
introduced code doesn't do so, it returns 0 instead of 1.
This introduces performance regression, reported by Dave Chinner:
v4 filesystem v5 filesystem
3.11+xfsdev: 220k files/s 225k files/s
3.12-git 180k files/s 185k files/s
3.12-git-revert 245k files/s 247k files/s
You can find more detailed information at:
https://lkml.org/lkml/2013/9/10/1
This patch corrects the return value of should_we_balance()
function as orignally intended.
With this patch, Dave Chinner reports that the regression is gone:
v4 filesystem v5 filesystem
3.11+xfsdev: 220k files/s 225k files/s
3.12-git 180k files/s 185k files/s
3.12-git-revert 245k files/s 247k files/s
3.12-git-fix 249k files/s 248k files/s
Reported-by: Dave Chinner <dchinner@redhat.com>
Tested-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Link: http://lkml.kernel.org/r/20130910065448.GA20368@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7f0a5e6cdae0..9b3fe1cd8f40 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5151,7 +5151,7 @@ static int should_we_balance(struct lb_env *env) * First idle cpu or the first cpu(busiest) in this sched group * is eligible for doing load balancing at this and above domains. */ - return balance_cpu != env->dst_cpu; + return balance_cpu == env->dst_cpu; } /* |