Messages in this thread | | | Subject | Re: [PATCH] sched: Call update_group_power only for local_group | From | Peter Zijlstra <> | Date | Fri, 02 Jul 2010 10:05:44 +0200 |
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On Thu, 2010-07-01 at 16:12 -0700, Venkatesh Pallipadi wrote: > commit 871e35b moved update_group_power() call in update_sg_lb_stats(), > resulting in it being called for each group, even though it only updates > the power of local group. As a result we have frequent redundant > update_group_power() calls. > > Move it back under "if (local_group)" condition. > > This reduces the number of calls to update_group_power by a factor of 4 > on my 4 core in 4 NUMA nodes test system.
Hrm,.. so Gautham removed that because for things like the NO_HZ balancer the initial balance_cpu == this_cpu constraint doesn't hold.
Not I don't think the local_group constraint holds for that either, so the below would again break that..
Should we perhaps have a conditional on this_rq->nohz_balance_kick or so?
> --- a/kernel/sched_fair.c > +++ b/kernel/sched_fair.c > @@ -2359,8 +2359,11 @@ static inline void update_sg_lb_stats(struct sched_domain *sd, > unsigned int balance_cpu = -1, first_idle_cpu = 0; > unsigned long avg_load_per_task = 0; > > - if (local_group) > + if (local_group) { > balance_cpu = group_first_cpu(group); > + update_group_power(sd, this_cpu); > + } > + > > /* Tally up the load of all CPUs in the group */ > max_cpu_load = 0;
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