linux-kernel - Re: [PATCH] perf script: Skip dummy event attr check

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Date:   Tue, 6 Sep 2022 21:50:47 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Xing Zhengjun <zhengjun.xing@...ux.intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ian Rogers <irogers@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Hongtao Yu <hoy@...com>, lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        "Liang, Kan" <kan.liang@...ux.intel.com>
Subject: Re: [PATCH] perf script: Skip dummy event attr check

Hello,

On Tue, Sep 6, 2022 at 7:49 PM Xing Zhengjun
<zhengjun.xing@...ux.intel.com> wrote:
>
> Hi,
>
> On 9/1/2022 12:23 AM, Arnaldo Carvalho de Melo wrote:
> > Em Wed, Aug 31, 2022 at 09:02:46AM -0700, Ian Rogers escreveu:
> >> On Wed, Aug 31, 2022 at 5:40 AM Jiri Olsa <jolsa@...nel.org> wrote:
> >>>
> >>> Hongtao Yu reported problem when displaying uregs in perf script
> >>> for system wide perf.data:
> >>>
> >>>    # perf script -F uregs | head -10
> >>>    Samples for 'dummy:HG' event do not have UREGS attribute set. Cannot print 'uregs' field.
> >>>
> >>> The problem is the extra dummy event added for system wide,
> >>> which does not have proper sample_type setup.
> >>>
> >>> Skipping attr check completely for dummy event as suggested
> >>> by Namhyung, because it does not have any samples anyway.
> >>>
> >>> Reported-by: Hongtao Yu <hoy@...com>
> >>> Suggested-by: Namhyung Kim <namhyung@...nel.org>
> >>> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> >>
> >> Acked-by: Ian Rogers <irogers@...gle.com>
> >
> > Thanks, applied to perf/urgent.
> >
> > - Arnaldo
>
> I have met a similar issue on hybrid systems such as ADL, I apply the
> patch, and it works OK for the normal mode.
>   # ./perf record  --intr-regs=di,r8,dx,cx -e
> br_inst_retired.near_call:p -c 1000 --per-thread true
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.024 MB perf.data (25 samples) ]
>
> # ./perf script -F iregs |head -5
>   ABI:2    CX:0xffff90e19d024ed8    DX:0x1    DI:0xffff90e19d024ed8
> R8:0xffffba5e437e7b30
>   ABI:2    CX:0x7f5239783000    DX:0x80000000    DI:0xffff90e1801eea00
>   R8:0x71
>   ABI:2    CX:0x40    DX:0x60    DI:0xffffffff9fde5ab8    R8:0x40
>   ABI:2    CX:0x0    DX:0xffffffffffffffff    DI:0xffff90e1877408e8
> R8:0x1
>   ABI:2    CX:0xcc0    DX:0x1    DI:0xffff90e187d17c60    R8:0x40
>
> But the issue still happened when running the test in the pipe mode. In
> the pipe mode, it calls process_attr() which still checks the attr for
> the dummy event, so the issue happened.
>
>   # ./perf record -o - --intr-regs=di,r8,dx,cx -e
> br_inst_retired.near_call:p -c 1000 --per-thread true 2>/dev/null|./perf
> script -F iregs |head -5
> Samples for 'dummy:HG' event do not have IREGS attribute set. Cannot
> print 'iregs' field.
> 0x120 [0x90]: failed to process type: 64
>
> I have one test patch which can fix the pipe mode issue.
>
>   ./perf record -o - --intr-regs=di,r8,dx,cx -e
> br_inst_retired.near_call:p -c 1000 --per-thread true 2>/dev/null|./perf
> script -F iregs |head -5
>   ABI:2    CX:0xffff90e18119e278    DX:0x0    DI:0xffff90e18119f858
> R8:0xffff90e18119e278
>   ABI:2    CX:0x0    DX:0x1    DI:0xfffffa2844a91580    R8:0x402
>   ABI:2    CX:0x0    DX:0x0    DI:0x100cca    R8:0x0
>   ABI:2    CX:0x0    DX:0x0    DI:0xffffffff9e997ca5    R8:0x0
>   ABI:2    CX:0x113ce8000    DX:0xffff90e198f46600
> DI:0xffff90e189de8000    R8:0x290
>
>
> Fixes: b91e5492f9d7 ("perf record: Add a dummy event on hybrid systems
> to collect metadata records")
> Signed-off-by: Zhengjun Xing <zhengjun.xing@...ux.intel.com>
> ---
>   tools/perf/builtin-script.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
> index 9152e3e45b69..2d863cdb19fe 100644
> --- a/tools/perf/builtin-script.c
> +++ b/tools/perf/builtin-script.c
> @@ -2429,6 +2429,8 @@ static int process_attr(struct perf_tool *tool,
> union perf_event *event,
>          }
>
>          if (evsel->core.attr.sample_type) {
> +               if (evsel__is_dummy_event(evsel))
> +                       return 0;

Maybe we can move this into evsel__check_attr().

Thanks,
Namhyung


>                  err = evsel__check_attr(evsel, scr->session);
>                  if (err)
>                          return err;
> --
> 2.25.1
>
> --
> Zhengjun Xing