Messages in this thread | | | Date | Thu, 16 Feb 2023 17:41:48 -0800 | From | Ricardo Neri <> | Subject | Re: [PATCH v3 06/10] sched/fair: Use the prefer_sibling flag of the current sched domain |
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On Thu, Feb 16, 2023 at 01:16:42PM +0100, Peter Zijlstra wrote: > On Wed, Feb 15, 2023 at 09:21:05PM -0800, Ricardo Neri wrote: > > > I tweaked the solution that Dietmar proposed: > > > > - sds->prefer_sibling = child && child->flags & SD_PREFER_SIBLING; > > + if (sds->busiest) > > + sds->prefer_sibling = sds->busiest->flags & SD_PREFER_SIBLING; > > > > This comes from the observation that the prefer_sibling setting acts on > > busiest group. It then depends on whether the busiest group, not the local > > group, has child sched sched domains. Today it works because in most cases > > both the local and the busiest groups have child domains with the SD_ > > PREFER_SIBLING flag. > > > > This would also satisfy sched domains with the SD_ASYM_CPUCAPACITY flag as > > prefer_sibling would not be set in that case. > > > > It would also conserve the current behavior at the NUMA level. We would > > not need to implement SD_SPREAD_TASKS. > > > > This would both fix the SMT vs non-SMT bug and be less invasive. > > > > Thoughts? > > That does look nice. Be sure to put in a nice comment too.
Will do!
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