Re: [REGRESSION] [PATCH v3 7/7] sched/eevdf: Move to a single runqueue

[Mike Galbraith]

On Wed, 2026-10-07 at 17:35 +0530, Aishwarya Rambhadran wrote:
> Hi all,
> 
> Thanks for the suggestions. I ran a couple of follow-up tests on the
> same AWS Graviton3 (m7g.metal) setup with v7.3-rc4:
> 
> 1. Disable WA_WEIGHT:
> echo NO_WA_WEIGHT > /sys/kernel/debug/sched/features
> 
> 2. Use the "smp" cgroup mode:
> echo smp > /sys/kernel/debug/sched/cgroup_mode
> 
> Both tests were run with 20 repeats across 2 boot sessions. Below are
> the request latency p99 results for schbench configurations discussed
> earlier (usec, smaller is better):
> 
> message-thread:16, worker-thread:16
> v7.2 = 662869
> v7.3-rc4 = 969557
> NO_WA_WEIGHT = 958541
> smp = 723098
> 
> message-thread:64, worker-thread:4
> v7.2 = 730453
> v7.3-rc4 = 942251
> NO_WA_WEIGHT = 740454
> smp = 818483
> 
> message-thread:32, worker-thread:4
> v7.2 = 74251
> v7.3-rc4 = 56725
> NO_WA_WEIGHT = 59008
> smp = 82053
> 
> For the m:16 t:16 case that I originally bisected, disabling WA_WEIGHT
> does not materially change the regression. Switching to cgroup_mode=smp,
> however, recovers most of it.

I took flat back to 7.2 (to test only that) and did a little mixed load
7.2-virgin vs 7.2+flat testing with defaults. CPU distribution delta
when switching competitor load configuration from 1 group of 8 to 4
groups of 2 vs a fixed 4 client netperf load made it clear that numbers
for anything cgroup vs cgroup will definitely wiggle more than usual.

	-Mike