Em Thu, Sep 10, 2020 at 11:15:42AM +0200, Jiri Olsa escreveu: > On Tue, Sep 08, 2020 at 01:42:24PM +0900, Namhyung Kim wrote: > > When we profile cgroup events with perf stat, it's very annoying to > > specify events and cgroups on the command line as it requires the > > mapping between events and cgroups. (Note that perf record can use > > cgroup sampling but it's not usable for perf stat).
> > I guess most cases we just want to use a same set of events (N) for > > all cgroups (M), but we need to specify NxM events and NxM cgroups. > > This is not good especially when profiling large number of cgroups: > > say M=200. > > So I added --multiply-cgroup option to make it easy for that case. It > > will create NxM events from N events and M cgroups. One more upside > > is that it can handle metrics too. > agreed that it's PITA to use -G option ;-) yeah, its great that someone is looking at cgroups improvements, thanks Namyung, its great to have you working on this! More below. > > For example, the following example measures IPC metric for 3 cgroups > > $ cat perf-multi-cgrp.sh > > #!/bin/sh > > METRIC=${1:-IPC} > > CGROUP_DIR=/sys/fs/cgroup/perf_event > > sudo mkdir $CGROUP_DIR/A $CGROUP_DIR/B $CGROUP_DIR/C > > # add backgroupd workload for each cgroup > > echo $$ | sudo tee $CGROUP_DIR/A/cgroup.procs > /dev/null > > yes > /dev/null & > > echo $$ | sudo tee $CGROUP_DIR/B/cgroup.procs > /dev/null > > yes > /dev/null & > > echo $$ | sudo tee $CGROUP_DIR/C/cgroup.procs > /dev/null > > yes > /dev/null & > > # run 'perf stat' in the root cgroup > > echo $$ | sudo tee $CGROUP_DIR/cgroup.procs > /dev/null > > perf stat -a -M $METRIC --multiply-cgroup -G A,B,C sleep 1 > > would it be easier to have new option for this? like: > > perf stat -a -M $METRIC --for-cgroup A,B,C > perf stat -a -M $METRIC --for-each-cgroup A,B,C > perf stat -a -M $METRIC --attach-cgroup A,B,C > perf stat -a -M $METRIC --attach-to-cgroup A,B,C > > I'm still not sure how the --multiply-cgroup deals with empty > cgroup A,,C but looks like we don't need this behaviour now? Yeah, I also didn't like the --multiply-cgroup thing, perhaps we can use a per-event term? or per group, for example: perf stat -a -M $METRIC/cgroups=A,B,C/ perf stat -a -e '{cycles,instructions,cache-misses}/cgroups=A,B,C/' Allowing wildcards or regexps would help with some use cases. We already have several terms that allows us to control per event knobs, this would be one more. - Arnaldo