Messages in this thread | | | Subject | Re: [PATCH] perf stat: Support per-cluster aggregation | From | Yicong Yang <> | Date | Wed, 29 Mar 2023 20:46:55 +0800 |
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On 2023/3/29 14:47, Namhyung Kim wrote: > 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. >
you mean specified the CPUs by a topology ID like this S56-D0-CLS158 then we actually filtering the CPUs in the CLS 158?
> I also wonder what if it runs on an old kernel which doesn't > have the cluster_id file.
It should work well but may not be proper for the cluster. There's no die topology nor related sysfs attributes on arm64, but --per-die works like:
[root@localhost perf]# perf stat -a -e cycles --per-die -- sleep 1
Performance counter stats for 'system wide':
S56-D0 64 12,700,186 cycles S7182-D0 64 20,297,320 cycles
1.003638080 seconds time elapsed
On a legacy kernel without cluster sysfs attributes, the output will be look like:
[root@localhost perf]# perf stat -a -e cycles --per-cluster -- sleep 1
Performance counter stats for 'system wide':
S56-D0-CLS-1 64 12,634,251 cycles S7182-D0-CLS-1 64 16,348,322 cycles
1.003696680 seconds time elapsed
The patch just assign -1 to the cluster id. I'll modify this to keep consistence with the output of --per-die. Thanks for catching this!
Thanks, Yicong
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