From: Ravi Bangoria <ravi.bangoria@amd.com>
To: Stephane Eranian <eranian@google.com>
Cc: peterz@infradead.org, kim.phillips@amd.com, acme@redhat.com,
jolsa@redhat.com, songliubraving@fb.com,
linux-kernel@vger.kernel.org,
Ravi Bangoria <ravi.bangoria@amd.com>
Subject: Re: [PATCH v6 10/12] perf tools: Improve IBS error handling
Date: Wed, 16 Mar 2022 16:37:06 +0530 [thread overview]
Message-ID: <d32a5a9f-f634-ea3e-d68e-b07c9bab9add@amd.com> (raw)
In-Reply-To: <CABPqkBQZRVqWPFG0Dvc6HGxNcDDb0raaRw4Ur27CvR5O8vwALg@mail.gmail.com>
Stephane,
On 16-Mar-22 5:33 AM, Stephane Eranian wrote:
> On Tue, Mar 15, 2022 at 12:46 AM Ravi Bangoria <ravi.bangoria@amd.com> wrote:
>>
>> Stephane,
>>
>> On 09-Feb-22 2:46 AM, Stephane Eranian wrote:
>>> From: Kim Phillips <kim.phillips@amd.com>
>>>
>>> improve the error message returned on failed perf_event_open() on AMD when
>>> using IBS.
>>>
>>> Output of executing 'perf record -e ibs_op// true' BEFORE this patch:
>>>
>>> The sys_perf_event_open() syscall returned with 22 (Invalid argument)for event (ibs_op//u).
>>> /bin/dmesg | grep -i perf may provide additional information.
>>>
>>> Output after:
>>>
>>> AMD IBS cannot exclude kernel events. Try running at a higher privilege level.
>>>
>>> Output of executing 'sudo perf record -e ibs_op// true' BEFORE this patch:
>>>
>>> Error:
>>> The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (ibs_op//).
>>> /bin/dmesg | grep -i perf may provide additional information.
>>>
>>> Output after:
>>>
>>> Error:
>>> AMD IBS may only be available in system-wide/per-cpu mode. Try using -a, or -C and workload affinity
>>
>> This patch seems to be causing regression to perf python test.
>>
>> Without this patch:
>>
>> $ sudo ./perf test -vvv 19
>> 19: 'import perf' in python :
>> --- start ---
>> test child forked, pid 145391
>> python usage test: "echo "import sys ; sys.path.append('python'); import perf" | '/usr/bin/python2' "
>> test child finished with 0
>> ---- end ----
>> 'import perf' in python: Ok
>>
>> With this patch:
>>
>> $ sudo ./perf test -vvv 19
>> 19: 'import perf' in python :
>> --- start ---
>> test child forked, pid 144415
>> python usage test: "echo "import sys ; sys.path.append('python'); import perf" | '/usr/bin/python2' "
>> Traceback (most recent call last):
>> File "<stdin>", line 1, in <module>
>> ImportError: python/perf.so: undefined symbol: perf_env__cpuid
>> test child finished with -1
>> ---- end ----
>> 'import perf' in python: FAILED!
>>
>
> The fix I sent you is just to prevent a potential SEGFAULT in
> is_amd_ibs(). I bet the test fails some perf_event_open()
> and ends up in strerror function and from there I don't see how the
> patch could impact the test, given you'd segfault
> otherwise.
>
> I tried on my side and with or without this patch this test fails. I
> think this looks like an unrelated issue.
That's strange. IIUC, python/perf.so needs to know about util/evsel.c
which can be done by adding an entry in util/python-ext-sources.
In any case, do we really need this patch now? For both the example given
in description, I see no difference with or without patch:
Without patch:
$ sudo ./perf record -e ibs_op// true
Error:
Invalid event (ibs_op//) in per-thread mode, enable system wide with '-a'.
$ ./perf record -e ibs_op// true
Error:
Invalid event (ibs_op//u) in per-thread mode, enable system wide with '-a'.
Same o/p with the patch as well.
Thanks,
Ravi
next prev parent reply other threads:[~2022-03-16 11:07 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-08 21:16 [PATCH v6 00/12] perf/x86/amd: Add AMD Fam19h Branch Sampling support Stephane Eranian
2022-02-08 21:16 ` [PATCH v6 01/12] perf/core: add perf_clear_branch_entry_bitfields() helper Stephane Eranian
2022-02-08 21:16 ` [PATCH v6 02/12] x86/cpufeatures: add AMD Fam19h Branch Sampling feature Stephane Eranian
2022-02-08 21:16 ` [PATCH v6 03/12] perf/x86/amd: add AMD Fam19h Branch Sampling support Stephane Eranian
2022-02-08 21:16 ` [PATCH v6 04/12] perf/x86/amd: add branch-brs helper event for Fam19h BRS Stephane Eranian
2022-02-08 21:16 ` [PATCH v6 05/12] perf/x86/amd: enable branch sampling priv level filtering Stephane Eranian
2022-02-08 21:16 ` [PATCH v6 06/12] perf/x86/amd: add AMD branch sampling period adjustment Stephane Eranian
2022-02-09 15:32 ` Peter Zijlstra
2022-03-04 15:45 ` Peter Zijlstra
2022-03-09 23:03 ` Stephane Eranian
2022-03-15 12:08 ` Peter Zijlstra
2022-03-17 17:11 ` Stephane Eranian
2022-02-08 21:16 ` [PATCH v6 07/12] perf/x86/amd: make Zen3 branch sampling opt-in Stephane Eranian
2022-02-08 21:16 ` [PATCH v6 08/12] ACPI: add perf low power callback Stephane Eranian
2022-02-08 21:16 ` [PATCH v6 09/12] perf/x86/amd: add idle hooks for branch sampling Stephane Eranian
2022-02-08 21:16 ` [PATCH v6 10/12] perf tools: Improve IBS error handling Stephane Eranian
2022-02-09 15:47 ` Arnaldo Carvalho de Melo
2022-03-15 6:49 ` Ravi Bangoria
2022-03-15 2:01 ` Stephane Eranian
2022-03-15 6:23 ` Ravi Bangoria
2022-03-15 7:12 ` Stephane Eranian
2022-03-15 7:45 ` Ravi Bangoria
2022-03-16 0:03 ` Stephane Eranian
2022-03-16 11:07 ` Ravi Bangoria [this message]
2022-03-16 11:16 ` Ravi Bangoria
2022-02-08 21:16 ` [PATCH v6 11/12] perf tools: Improve error handling of AMD Branch Sampling Stephane Eranian
2022-02-16 14:17 ` Arnaldo Carvalho de Melo
2022-02-08 21:16 ` [PATCH v6 12/12] perf report: add addr_from/addr_to sort dimensions Stephane Eranian
2022-02-16 14:21 ` Arnaldo Carvalho de Melo
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