Re: [PATCH v3 0/7] sched: Flatten the pick

[Szabina Korbai <szkorbai@linux.ibm.com>]

On Mon, 2026-08-17 at 22:05 +0530, K Prateek Nayak wrote:
> Hello Szabina,
> 
> On 8/17/2026 9:35 PM, Szabina Korbai wrote:
> > Hello Peter,
> > 
> > We ran the same benchmarks (schbench, sysbench, hackbench) as
> > Shubhang
> > has on s390 on an LPAR running fedora 43 with 32 vCPUs.
> > 
> > We ran the benchmarks for each of the cgroup modes, and for the
> > baseline, we chose the commit prior to the patches (f666241e6bd5 -
> > sched/fair: Unify cfs_rq throttling via account_cfs_rq_runtime() ).
> > 
> > We have also tried running stress-ng in parallel with the
> > benchmarks
> > (set to generate 50% or 90% utilization for each vCPU).
> > 
> > Compared to simply running the benchmarks on their own, this has
> > revealed some performance trade-offs that the move to a single
> > runqueue
> > can introduce.
> 
> Are you using tip:sched/core at commit 68e3748781 ("sched/fair: Fix
> flat
> hierarchy") for the flat_cg numbers or did you checkout at
> 85570f10a4c6
> ("sched/eevdf: Move to a single runqueue")?
> 
> There are a couple fixes for vruntime update and Vincent's
> optimizations
> for preemption bits which might make a difference to the overall
> results.


Hi Prateek,

thank you, that's a good call. I did checkout at "Move to a single
runqueue". Let me try it with the fix included, see how the results are
affected.

Regards,

-- 
Szabina Korbai

Linux on Z development
Software Labs Campus Unlimited Company
25 North Wall Quay,
Dublin 1,
D01 H104,
Ireland

szkorbai@linux.ibm.com


IBM