Messages in this thread Patch in this message | | | Date | Mon, 1 Jun 2015 15:38:16 -0400 | From | Josef Bacik <> | Subject | Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for BALANCE_WAKE |
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On 05/29/2015 05:03 PM, Josef Bacik wrote: > On 05/28/2015 07:05 AM, Peter Zijlstra wrote: >> >> So maybe you want something like the below; that cures the thing Morten >> raised, and we continue looking for sd, even after we found affine_sd. >> >> It also avoids the pointless idle_cpu() check Mike raised by making >> select_idle_sibling() return -1 if it doesn't find anything. >> >> Then it continues doing the full balance IFF sd was set, which is keyed >> off of sd->flags. >> >> And note (as Mike already said), BALANCE_WAKE does _NOT_ look for idle >> CPUs, it looks for the least loaded CPU. And its damn expensive. >> >> >> Rewriting this entire thing is somewhere on the todo list :/ >> >
Ok I got this patch to give me the same performance as all our other crap, just need to apply this incremental
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b71eb2b..e11cfec 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4761,13 +4761,10 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
if (tmp->flags & sd_flag) sd = tmp; - else if (!want_affine || (want_affine && affine_sd)) - break; }
if (affine_sd && cpu != prev_cpu && wake_affine(affine_sd, p, sync)) { prev_cpu = cpu; - sd = NULL; /* WAKE_AFFINE trumps BALANCE_WAKE */ }
if (sd_flag & SD_BALANCE_WAKE) { And everything works fine. Does that seem reasonable? Thanks,
Josef
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