sched: optimize group load balancer

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I noticed that tg_shares_up() unconditionally takes rq-locks for all cpus
in the sched_domain. This hurts.

We need the rq-locks whenever we change the weight of the per-cpu group sched
entities. To allevate this a little, only change the weight when the new
weight is at least shares_thresh away from the old value.

This avoids the rq-lock for the top level entries, since those will never
be re-weighted, and fuzzes the lower level entries a little to gain performance
in semi-stable situations.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

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Peter Zijlstra 2008-10-17 19:27:02 +02:00 • committed by Ingo Molnar

parent b0aa51b999

commit ffda12a17a

3 changed files with 36 additions and 20 deletions

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kernel/sysctl.c

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