tree 79fe8aae79a41b467f2cdd055036b3017642a9f6
parent b0aa51b999c449e5e3f9faa1ee406e052d407fe7
author Peter Zijlstra <a.p.zijlstra@chello.nl> 1224264422 +0200
committer Ingo Molnar <mingo@elte.hu> 1224504302 +0200

sched: optimize group load balancer

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>