From ffda12a17a324103e9900fa1035309811eecbfe5 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 17 Oct 2008 19:27:02 +0200 Subject: 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 Signed-off-by: Ingo Molnar --- include/linux/sched.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/sched.h b/include/linux/sched.h index 6eda6ad735dc..4f59c8e8597d 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1621,6 +1621,7 @@ extern unsigned int sysctl_sched_features; extern unsigned int sysctl_sched_migration_cost; extern unsigned int sysctl_sched_nr_migrate; extern unsigned int sysctl_sched_shares_ratelimit; +extern unsigned int sysctl_sched_shares_thresh; int sched_nr_latency_handler(struct ctl_table *table, int write, struct file *file, void __user *buffer, size_t *length, -- cgit v1.2.3