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Date:   Mon, 16 Oct 2023 12:38:12 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Ingo Molnar <mingo@kernel.org>
Cc:     Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
        Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v3] perf bench sched pipe: Add -G/--cgroups option
Message-ID: <ZS1Y5PhXhp384ynY@kernel.org>
References: <20231016044225.1125674-1-namhyung@kernel.org>
 <ZS0D53ckVx356k4o@gmail.com>
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Em Mon, Oct 16, 2023 at 11:35:35AM +0200, Ingo Molnar escreveu:
> 
> 
> * Namhyung Kim <namhyung@kernel.org> wrote:
> 
> > +	/* try cgroup v2 interface first */
> > +	if (threaded)
> > +		fd = openat(cgrp->fd, "cgroup.threads", O_WRONLY);
> > +	else
> > +		fd = openat(cgrp->fd, "cgroup.procs", O_WRONLY);
> > +
> > +	/* try cgroup v1 if failed */
> > +	if (fd < 0)
> > +		fd = openat(cgrp->fd, "tasks", O_WRONLY);
> > +
> > +	if (fd < 0) {
> > +		char mnt[PATH_MAX];
> > +
> > +		printf("Failed to open cgroup file in %s\n", cgrp->name);
> > +
> > +		if (cgroupfs_find_mountpoint(mnt, sizeof(mnt), "perf_event") == 0)
> > +			printf(" Hint: create the cgroup first, like 'mkdir %s/%s'\n",
> > +			       mnt, cgrp->name);
> 
> Ok, this works too I suppose.
> 
> Acked-by: Ingo Molnar <mingo@kernel.org>

I'm not getting that:

[root@five ~]# perf bench sched pipe -l 10000 -G AAA,BBB
# Running 'sched/pipe' benchmark:
no access to cgroup /sys/fs/cgroup/AAA
cannot open sender cgroup: AAA
 Usage: perf bench sched pipe <options>

    -G, --cgroups <SEND,RECV>
                          Put sender and receivers in given cgroups
[root@five ~]#

Its better now as it bails out, but it is not emitting any message that
helps with running the test, well, there is that /sys/fs/cgroup/AAA
path, lemme try doing a mkdir:

[root@five ~]# perf bench sched pipe -l 10000 -G AAA,BBB
# Running 'sched/pipe' benchmark:
no access to cgroup /sys/fs/cgroup/BBB
cannot open receiver cgroup: BBB
 Usage: perf bench sched pipe <options>

    -G, --cgroups <SEND,RECV>
                          Put sender and receivers in given cgroups
[root@five ~]#

[root@five ~]# perf bench sched pipe -l 10000 -G AAA,BBB
# Running 'sched/pipe' benchmark:
[root@five ~]#

It seems to be bailing out but doesn't run the test nor emits any
warning.

I'm using v3. I'll try to debug it a bit.

- Arnaldo