Re: [PATCH] lib/group_cpus: make group CPU cluster aware
From: Guo, Wangyang
Date: Sun Dec 21 2025 - 22:03:10 EST
On 12/22/2025 3:10 AM, Andrew Morton wrote:
On Fri, 24 Oct 2025 10:30:38 +0800 Wangyang Guo <wangyang.guo@xxxxxxxxx> wrote:Thanks for your reminder, will update changelog in next version. We see 15%+ performance difference in FIO libaio/randread/bs=8k.
As CPU core counts increase, the number of NVMe IRQs may be smaller than
the total number of CPUs. This forces multiple CPUs to share the same
IRQ. If the IRQ affinity and the CPU’s cluster do not align, a
performance penalty can be observed on some platforms.
It would be helpful to quantify "performance penalty". At least give
readers some approximate understanding of how serious this issue is,
please.
This patch improves IRQ affinity by grouping CPUs by cluster within each
NUMA domain, ensuring better locality between CPUs and their assigned
NVMe IRQs.
Reviewed-by: Tianyou Li <tianyou.li@xxxxxxxxx>
Reviewed-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
Tested-by: Dan Liang <dan.liang@xxxxxxxxx>
Signed-off-by: Wangyang Guo <wangyang.guo@xxxxxxxxx>
Patch hasn't attracted additional review so I'll queue this version for
some testing in mm.git's mm-nonmm-unstable branch. I'll add a
note-to-self that a changelog addition is desirable.
Thanks a lot for your time and support! Please let me know if you have any further comments or guidance. Any feedback would be appreciated.
BR
Wangyang