Re: [PATCH] perf test: Fix fails of perf stat --bpf-counters --for-each-cgroup on s390

[Namhyung Kim]

On Fri, Dec 8, 2023 at 3:30 AM Thomas Richter <tmricht@xxxxxxxxxxxxx> wrote:
>
> On 12/8/23 12:07, Thomas Richter wrote:
> > On 12/8/23 00:26, Namhyung Kim wrote:
> >
> >> Thanks for the patch.  But I think it should support
> >> machines without systemd (or maybe with old versions).
> >>
> >> Also probably you want to reset the behavior after
> >> the test.  I think we can just run some built-in test
> >> workload like `perf test -w thloop`.
> >>
> >> Thanks,
> >> Namhyung
> >
> > Thanks for our feedback.
> > Well regarding the use of systemd daemon-reexec the manual says
> > this command restarts the systemd triggered processes.
> > There is nothing to reset. All ports stay active while the command
> > is processed.
> >
> > I tried your 'perf test -w thloop`, but that did not trigger
> > anything on system.slice.
> >
> > I do not understand enough about cgroups and system.slice, but I am
> > under the impression, that the system.slice just increment counters
> > when executed by processes under systemd control. Maybe I am wrong.

Ah, you're right.  It needs to run the task somewhere in the system.slice.
Then it'd be hard to get a proper cgroup name generally. Hmm..

My concern was it'd bind system daemons on the CPU 0 and 1 after the
test.  Probably you could run it at the end of the test again without taskset.

> >
> > The only other workload which always incremented system.slice counters
> > was 'ssh localhost ls -l', which involves local login and a running sshd.

But it won't work if the system doesn't have sshd.

Thanks,
Namhyung