lkml.org 
[lkml]   [2021]   [Nov]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 2/2] perf evsel: Improve error message for uncore events
On Mon, Nov 29, 2021 at 10:55 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Hi Ian,
>
> On Mon, Nov 29, 2021 at 3:48 PM Ian Rogers <irogers@google.com> wrote:
> >
> > On Sun, Nov 28, 2021 at 8:58 AM Jiri Olsa <jolsa@redhat.com> wrote:
> > >
> > > On Mon, Nov 22, 2021 at 06:03:41PM -0800, Ian Rogers wrote:
> > > > When a group has multiple events and the leader fails it can yield
> > > > errors like:
> > > >
> > > > $ perf stat -e '{uncore_imc/cas_count_read/},instructions' /bin/true
> > > > Error:
> > > > The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (uncore_imc/cas_count_read/).
> > > > /bin/dmesg | grep -i perf may provide additional information.
> > > >
> > > > However, when not the group leader <not supported> is given:
> > > >
> > > > $ perf stat -e '{instructions,uncore_imc/cas_count_read/}' /bin/true
> > > > ...
> > > > 1,619,057 instructions
> > > > <not supported> MiB uncore_imc/cas_count_read/
> > > >
> > > > This is necessary because get_group_fd will fail if the leader fails and
> > > > is the direct result of the check on line 750 of builtin-stat.c in
> > > > stat_handle_error that returns COUNTER_SKIP for the latter case.
> > > >
> > > > This patch improves the error message to:
> > > >
> > > > $ perf stat -e '{uncore_imc/cas_count_read/},instructions' /bin/true
> > > > Error:
> > > > Invalid event (uncore_imc/cas_count_read/) in per-thread mode, enable system wide with '-a'.
> > > >
> > > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > > ---
> > > > tools/perf/util/evsel.c | 5 +++++
> > > > 1 file changed, 5 insertions(+)
> > > >
> > > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > > > index a59fb2ecb84e..48696ff4bddb 100644
> > > > --- a/tools/perf/util/evsel.c
> > > > +++ b/tools/perf/util/evsel.c
> > > > @@ -2950,6 +2950,11 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
> > > > return scnprintf(msg, size, "wrong clockid (%d).", clockid);
> > > > if (perf_missing_features.aux_output)
> > > > return scnprintf(msg, size, "The 'aux_output' feature is not supported, update the kernel.");
> > > > + if ((evsel__leader(evsel) == evsel) &&
> > > > + (evsel->core.leader->nr_members > 1))
> > > > + return scnprintf(msg, size,
> > > > + "Invalid event (%s) in per-thread mode, enable system wide with '-a'.",
> > > > + evsel__name(evsel));
> > >
> > > should we rather check 'target' pointer for the per-thread mode?
> > > I'm not sure that per-thread mode will always be the case for the failure
> >
> > Unfortunately the target isn't populated at that point:
>
> It might be populated properly, as in this case
> it should have no target. I think you can use
> !target__has_cpu().

Thanks :-) I'm not sure having !target__has_cpu is intention
revealing. Perhaps changing the error to say that an
invalid/unsupported event can't be the group leader, unless it is the
only event, and then suggest system wide mode.

Thanks,
Ian

> Thanks,
> Namhyung
>
>
> >
> > gdb --args perf stat -e '{uncore_imc/cas_count_write/},instructions' /bin/true
> > (gdb) p *target
> > $2 = {pid = 0x0, tid = 0x0, cpu_list = 0x0, uid_str = 0x0, bpf_str =
> > 0x0, uid = 4294967295, system_wide = false, uses_mmap = false,
> > default_per_cpu = false, per_thread = false, use_bpf = false, hybrid
> > = false, attr_map = 0x0}
> >
> > #0 evsel__open_strerror (evsel=0x616000015680, target=0x5555586aa140
> > <target>, err=22, msg=0x7fffffff78d0 "]k\264WUU", size=8192)
> > at util/evsel.c:2857
> > #1 0x00005555561744e8 in stat_handle_error (counter=0x616000015680)
> > at builtin-stat.c:771
> > #2 0x0000555556174f05 in __run_perf_stat (argc=1,
> > argv=0x7fffffffe450, run_idx=0) at builtin-stat.c:852
> > #3 0x00005555561763e1 in run_perf_stat (argc=1, argv=0x7fffffffe450,
> > run_idx=0) at builtin-stat.c:1048
> > #4 0x000055555617df82 in cmd_stat (argc=1, argv=0x7fffffffe450) at
> > builtin-stat.c:2550
> > #5 0x00005555562f36b8 in run_builtin (p=0x5555586bad00
> > <commands+288>, argc=4, argv=0x7fffffffe450) at perf.c:313
> > #6 0x00005555562f3c11 in handle_internal_command (argc=4,
> > argv=0x7fffffffe450) at perf.c:365
> > #7 0x00005555562f3fce in run_argv (argcp=0x7fffffffe230,
> > argv=0x7fffffffe240) at perf.c:409
> > #8 0x00005555562f47bd in main (argc=4, argv=0x7fffffffe450) at perf.c:539
> >
> > Thanks,
> > Ian
> >
> > > jirka
> > >
> > > > break;
> > > > case ENODATA:
> > > > return scnprintf(msg, size, "Cannot collect data source with the load latency event alone. "
> > > > --
> > > > 2.34.0.rc2.393.gf8c9666880-goog
> > > >
> > >

\
 
 \ /
  Last update: 2021-11-30 08:58    [W:0.048 / U:0.428 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site