Messages in this thread Patch in this message | | | Subject | Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for BALANCE_WAKE | From | Mike Galbraith <> | Date | Thu, 18 Jun 2015 06:12:45 +0200 |
| |
On Wed, 2015-06-17 at 20:46 -0700, Josef Bacik wrote: > On 06/17/2015 05:55 PM, Mike Galbraith wrote: > > On Wed, 2015-06-17 at 11:06 -0700, Josef Bacik wrote: > >> On 06/11/2015 10:35 PM, Mike Galbraith wrote: > >>> On Thu, 2015-05-28 at 13:05 +0200, Peter Zijlstra wrote: > > > >>> If sd == NULL, we fall through and try to pull wakee despite nacked-by > >>> tsk_cpus_allowed() or wake_affine(). > >>> > >> > >> So maybe add a check in the if (sd_flag & SD_BALANCE_WAKE) for something > >> like this > >> > >> if (tmp >= 0) { > >> new_cpu = tmp; > >> goto unlock; > >> } else if (!want_affine) { > >> new_cpu = prev_cpu; > >> } > >> > >> so we can make sure we're not being pushed onto a cpu that we aren't > >> allowed on? Thanks, > > > > The buglet is a messenger methinks. You saying the patch helped without > > SD_BALANCE_WAKE being set is why I looked. The buglet would seem to say > > that preferring cache is not harming your load after all. It now sounds > > as though wake_wide() may be what you're squabbling with. > > > > Things aren't adding up all that well. > > Yeah I'm horribly confused. The other thing is I had to switch clusters > (I know, I know, I'm changing the parameters of the test). So these new > boxes are haswell boxes, but basically the same otherwise, 2 socket 12 > core with HT, just newer/faster CPUs. I'll re-run everything again and > give the numbers so we're all on the same page again, but as it stands > now I think we have this > > 3.10 with wake_idle forward ported - good > 4.0 stock - 20% perf drop > 4.0 w/ Peter's patch - good > 4.0 w/ Peter's patch + SD_BALANCE_WAKE - 5% perf drop > > I can do all these iterations again to verify, is there any other > permutation you'd like to see? Thanks,
Yeah, after re-baseline, please apply/poke these buttons individually in 4.0-virgin.
(cat /sys/kernel/debug/sched_features, prepend NO_, echo it back)
--- kernel/sched/fair.c | 4 ++-- kernel/sched/features.h | 2 ++ 2 files changed, 4 insertions(+), 2 deletions(-)
--- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4506,7 +4506,7 @@ static int wake_affine(struct sched_doma * If we wake multiple tasks be careful to not bounce * ourselves around too much. */ - if (wake_wide(p)) + if (sched_feat(WAKE_WIDE) && wake_wide(p)) return 0; idx = sd->wake_idx; @@ -4682,7 +4682,7 @@ static int select_idle_sibling(struct ta struct sched_group *sg; int i = task_cpu(p); - if (idle_cpu(target)) + if (!sched_feat(PREFER_IDLE) || idle_cpu(target)) return target; /* --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -59,6 +59,8 @@ SCHED_FEAT(TTWU_QUEUE, true) SCHED_FEAT(FORCE_SD_OVERLAP, false) SCHED_FEAT(RT_RUNTIME_SHARE, true) SCHED_FEAT(LB_MIN, false) +SCHED_FEAT(PREFER_IDLE, true) +SCHED_FEAT(WAKE_WIDE, true) /* * Apply the automatic NUMA scheduling policy. Enabled automatically
| |