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Date:   Thu, 8 Sep 2022 14:56:46 +0800
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Subject: Re: [PATCH] perf script: Skip dummy event attr check
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To:     Jiri Olsa <olsajiri@gmail.com>, Namhyung Kim <namhyung@kernel.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Ian Rogers <irogers@google.com>, Hongtao Yu <hoy@fb.com>,
        lkml <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        linux-perf-users <linux-perf-users@vger.kernel.org>,
        "Liang, Kan" <kan.liang@linux.intel.com>
References: <20220831124041.219925-1-jolsa@kernel.org>
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From:   Xing Zhengjun <zhengjun.xing@linux.intel.com>
In-Reply-To: <YxinpgT93BIyTqLc@krava>
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On 9/7/2022 10:16 PM, Jiri Olsa wrote:
> On Wed, Sep 07, 2022 at 01:14:52AM -0700, Namhyung Kim wrote:
>> On Wed, Sep 7, 2022 at 1:09 AM Jiri Olsa <olsajiri@gmail.com> wrote:
>>>
>>> On Wed, Sep 07, 2022 at 01:19:32PM +0800, Xing Zhengjun wrote:
>>>>
>>>>
>>>> On 9/7/2022 12:50 PM, Namhyung Kim wrote:
>>>>> Hello,
>>>>>
>>>>> On Tue, Sep 6, 2022 at 7:49 PM Xing Zhengjun
>>>>> <zhengjun.xing@linux.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@kernel.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@fb.com>
>>>>>>>>> Suggested-by: Namhyung Kim <namhyung@kernel.org>
>>>>>>>>> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
>>>>>>>>
>>>>>>>> Acked-by: Ian Rogers <irogers@google.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@linux.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
>>>>
>>>> Yes, the following changes in evsel__check_attr() can fix both normal and
>>>> pipe mode issues, Otherwise, we have to patch everywhere when
>>>> evsel__check_attr() is called.
>>>>
>>>> diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
>>>> index 13580a9c50b8..fb76e3191858 100644
>>>> --- a/tools/perf/builtin-script.c
>>>> +++ b/tools/perf/builtin-script.c
>>>> @@ -451,6 +451,9 @@ static int evsel__check_attr(struct evsel *evsel, struct
>>>> perf_session *session)
>>>>          allow_user_set = perf_header__has_feat(&session->header,
>>>>                                                 HEADER_AUXTRACE);
>>>>
>>>> +       if (evsel__is_dummy_event(evsel))
>>>> +               allow_user_set = true;
>>>> +
>>>
>>> hm, do you need to pass allow_user_set to UREGS check then?
>>
>> Well.. actually I thought we can simply return 0 for a dummy event.
> 
> true :-)
> 
> jirka

Thanks all, I will post a patch based on it soon.

-- 
Zhengjun Xing