Messages in this thread | | | From | Namhyung Kim <> | Date | Tue, 28 Mar 2023 23:47:23 -0700 | Subject | Re: [PATCH] perf stat: Support per-cluster aggregation |
| |
Hello,
On Fri, Mar 24, 2023 at 11:09 AM Chen, Tim C <tim.c.chen@intel.com> wrote: > > > > >From: Yicong Yang <yangyicong@hisilicon.com> > > > >Some platforms have 'cluster' topology and CPUs in the cluster will share > >resources like L3 Cache Tag (for HiSilicon Kunpeng SoC) or L2 cache (for Intel > >Jacobsville). Currently parsing and building cluster topology have been > >supported since [1]. > > > >perf stat has already supported aggregation for other topologies like die or > >socket, etc. It'll be useful to aggregate per-cluster to find problems like L3T > >bandwidth contention or imbalance. > > > >This patch adds support for "--per-cluster" option for per-cluster aggregation. > >Also update the docs and related test. The output will be like: > > > >[root@localhost tmp]# perf stat -a -e LLC-load --per-cluster -- sleep 5 > > > > Performance counter stats for 'system wide': > > > >S56-D0-CLS158 4 1,321,521,570 LLC-load > >S56-D0-CLS594 4 794,211,453 LLC-load > >S56-D0-CLS1030 4 41,623 LLC-load > >S56-D0-CLS1466 4 41,646 LLC-load > >S56-D0-CLS1902 4 16,863 LLC-load > >S56-D0-CLS2338 4 15,721 LLC-load > >S56-D0-CLS2774 4 22,671 LLC-load > >[...] > > Overall it looks good. You can add my reviewed-by. > > I wonder if we could enhance the help message > in perf stat to tell user to refer to > /sys/devices/system/cpu/cpuX/topology/*_id > to map relevant ids back to overall cpu topology. > > For example the above example, cluster S56-D0-CLS158 has > really heavy load. It took me a while > going through the code to figure out how to find > the info that maps cluster id to cpu.
Maybe we could enhance the cpu filter to accept something like -C S56-D0-CLS158.
I also wonder what if it runs on an old kernel which doesn't have the cluster_id file.
Thanks, Namhyung
| |