Re: [PATCH v2 00/10] sched: Flatten the pick

[Peter Zijlstra]

On Tue, May 12, 2026 at 10:42:33AM +0200, Vincent Guittot wrote:

> 
> I haven't reviewed the patches yet but I ran some tests with it while
> testing sched latency related changes for short slice wakeup
> preemption. I have some large hackbench regressions with this series
> on HMP system with and without EAS. those figures are unexpected
> because the benchs run on root cfs
> 
> One example with hackbench 8 groups thread pipe
> tip/sched/core  tip/sched/core          +this patchset          +this patchset
> slice 2.8ms     16ms                    2.8ms                   16ms
> dragonboard rb5 with EAS
> 0,748(+/-4,6%)  0,621(+/-3.6%) +17%     1,915(+/-7.9%) -156%
> 0,689(+/- 9.1%) +8%
> 
> radxa orion6 HMP without EAS
> 0,588(+/-5.8%)  0,677(+/-5.9%) -15%     1,505(+/-10%) -156%
> 1,071(+/-5.9%) -82%
> 
> Increasing the slice partly removes regressions but tis is surprising
> because the bench runs at root cfs and I thought that results will not
> change in such a case
> 
> I will review the patchset and try to get what is going wrong

Yeah, that is unexpected. Let me go have another look too.