Re: [PATCH] perf test: Retry without grouping for all metrics test

[Arnaldo Carvalho de Melo]

Em Wed, Dec 06, 2023 at 08:35:23AM -0800, Ian Rogers escreveu:
> On Wed, Dec 6, 2023 at 5:08 AM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
> > Humm, I'm not being able to reproduce here the problem, before applying
> > this patch:
 
> Please don't apply the patch. The patch masks a bug in metrics/PMUs

I didn't

> and the proper fix was:
> 8d40f74ebf21 perf vendor events amd: Fix large metrics
> https://lore.kernel.org/r/20230706063440.54189-1-sandipan.das@xxxxxxx

that is upstream:

⬢[acme@toolbox perf-tools-next]$ git log tools/perf/pmu-events/arch/x86/amdzen1/recommended.json
commit 8d40f74ebf217d3b9e9b7481721e6236b857cc55
Author: Sandipan Das <sandipan.das@xxxxxxx>
Date:   Thu Jul 6 12:04:40 2023 +0530

    perf vendor events amd: Fix large metrics

    There are cases where a metric requires more events than the number of
    available counters. E.g. AMD Zen, Zen 2 and Zen 3 processors have four
    data fabric counters but the "nps1_die_to_dram" metric has eight events.

    By default, the constituent events are placed in a group and since the
    events cannot be scheduled at the same time, the metric is not computed.
    The "all metrics" test also fails because of this.

    Use the NO_GROUP_EVENTS constraint for such metrics which anyway expect
    the user to run perf with "--metric-no-group".

    E.g.

      $ sudo perf test -v 101

    Before:

      101: perf all metrics test                                           :
      --- start ---
      test child forked, pid 37131
      Testing branch_misprediction_ratio
      Testing all_remote_links_outbound
      Testing nps1_die_to_dram
      Metric 'nps1_die_to_dram' not printed in:
      Error:
      Invalid event (dram_channel_data_controller_4) in per-thread mode, enable system wide with '-a'.
      Testing macro_ops_dispatched
      Testing all_l2_cache_accesses
      Testing all_l2_cache_hits
      Testing all_l2_cache_misses
      Testing ic_fetch_miss_ratio
      Testing l2_cache_accesses_from_l2_hwpf
      Testing l2_cache_misses_from_l2_hwpf
      Testing op_cache_fetch_miss_ratio
      Testing l3_read_miss_latency
      Testing l1_itlb_misses
      test child finished with -1
      ---- end ----
      perf all metrics test: FAILED!

    After:

      101: perf all metrics test                                           :
      --- start ---
      test child forked, pid 43766
      Testing branch_misprediction_ratio
      Testing all_remote_links_outbound
      Testing nps1_die_to_dram
      Testing macro_ops_dispatched
      Testing all_l2_cache_accesses
      Testing all_l2_cache_hits
      Testing all_l2_cache_misses
      Testing ic_fetch_miss_ratio
      Testing l2_cache_accesses_from_l2_hwpf
      Testing l2_cache_misses_from_l2_hwpf
      Testing op_cache_fetch_miss_ratio
      Testing l3_read_miss_latency
      Testing l1_itlb_misses
      test child finished with 0
      ---- end ----
      perf all metrics test: Ok

    Reported-by: Ayush Jain <ayush.jain3@xxxxxxx>
    Suggested-by: Ian Rogers <irogers@xxxxxxxxxx>
    Signed-off-by: Sandipan Das <sandipan.das@xxxxxxx>
    Acked-by: Ian Rogers <irogers@xxxxxxxxxx>
    Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
    Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
    Cc: Ananth Narayan <ananth.narayan@xxxxxxx>
    Cc: Ingo Molnar <mingo@xxxxxxxxxx>
    Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
    Cc: Mark Rutland <mark.rutland@xxxxxxx>
    Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
    Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
    Cc: Ravi Bangoria <ravi.bangoria@xxxxxxx>
    Cc: Santosh Shukla <santosh.shukla@xxxxxxx>
    Link: https://lore.kernel.org/r/20230706063440.54189-1-sandipan.das@xxxxxxx
    Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx
 
> > Ian, I also stumbled on this:

> > [root@five ~]# perf stat -M dram_channel_data_controller_4
> > Cannot find metric or group `dram_channel_data_controller_4'
> > ^C
> >  Performance counter stats for 'system wide':

> >         284,908.91 msec cpu-clock                        #   32.002 CPUs utilized
> >          6,485,456      context-switches                 #   22.763 K/sec
> >                719      cpu-migrations                   #    2.524 /sec
> >             32,800      page-faults                      #  115.125 /sec

<SNIP>

> > I.e. -M should bail out at that point (Cannot find metric or group `dram_channel_data_controller_4'), no?

> We could. I suspect the code has always just not bailed out. I'll put
> together a patch adding the bail out.

Great, thanks,

- Arnaldo