From: Andi Kleen <ak@linux.intel.com>
To: Wei Li <liwei391@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
huawei.libin@huawei.com, Namhyung Kim <namhyung@kernel.org>,
Jiri Olsa <jolsa@redhat.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/2] perf stat: Fix segfault when counting armv8_pmu events
Date: Tue, 22 Sep 2020 12:50:35 -0700 [thread overview]
Message-ID: <20200922195035.GA42577@tassilo.jf.intel.com> (raw)
In-Reply-To: <20200922192321.GL13818@tassilo.jf.intel.com>
On Tue, Sep 22, 2020 at 12:23:21PM -0700, Andi Kleen wrote:
> > After debugging, i found the root reason is that the xyarray fd is created
> > by evsel__open_per_thread() ignoring the cpu passed in
> > create_perf_stat_counter(), while the evsel' cpumap is assigned as the
> > corresponding PMU's cpumap in __add_event(). Thus, the xyarray fd is created
> > with ncpus of dummy cpumap and an out of bounds 'cpu' index will be used in
> > perf_evsel__close_fd_cpu().
> >
> > To address this, add a flag to mark this situation and avoid using the
> > affinity technique when closing/enabling/disabling events.
>
> The flag seems like a hack. How about figuring out the correct number of
> CPUs and using that?
Also would like to understand what's different on ARM64 than other architectures.
Or could this happen on x86 too?
-Andi
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WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <ak@linux.intel.com>
To: Wei Li <liwei391@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, huawei.libin@huawei.com
Subject: Re: [PATCH 1/2] perf stat: Fix segfault when counting armv8_pmu events
Date: Tue, 22 Sep 2020 12:50:35 -0700 [thread overview]
Message-ID: <20200922195035.GA42577@tassilo.jf.intel.com> (raw)
In-Reply-To: <20200922192321.GL13818@tassilo.jf.intel.com>
On Tue, Sep 22, 2020 at 12:23:21PM -0700, Andi Kleen wrote:
> > After debugging, i found the root reason is that the xyarray fd is created
> > by evsel__open_per_thread() ignoring the cpu passed in
> > create_perf_stat_counter(), while the evsel' cpumap is assigned as the
> > corresponding PMU's cpumap in __add_event(). Thus, the xyarray fd is created
> > with ncpus of dummy cpumap and an out of bounds 'cpu' index will be used in
> > perf_evsel__close_fd_cpu().
> >
> > To address this, add a flag to mark this situation and avoid using the
> > affinity technique when closing/enabling/disabling events.
>
> The flag seems like a hack. How about figuring out the correct number of
> CPUs and using that?
Also would like to understand what's different on ARM64 than other architectures.
Or could this happen on x86 too?
-Andi
next prev parent reply other threads:[~2020-09-22 19:51 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 3:13 [PATCH 0/2] perf stat: Unbreak perf stat with ARMv8 PMU events Wei Li
2020-09-22 3:13 ` Wei Li
2020-09-22 3:13 ` [PATCH 1/2] perf stat: Fix segfault when counting armv8_pmu events Wei Li
2020-09-22 3:13 ` Wei Li
2020-09-22 19:23 ` Andi Kleen
2020-09-22 19:23 ` Andi Kleen
2020-09-22 19:50 ` Andi Kleen [this message]
2020-09-22 19:50 ` Andi Kleen
2020-09-24 14:14 ` liwei (GF)
2020-09-24 14:14 ` liwei (GF)
2020-09-23 5:44 ` Jiri Olsa
2020-09-23 5:44 ` Jiri Olsa
2020-09-23 13:49 ` Namhyung Kim
2020-09-23 13:49 ` Namhyung Kim
2020-09-23 14:07 ` Jiri Olsa
2020-09-23 14:07 ` Jiri Olsa
2020-09-23 14:15 ` Namhyung Kim
2020-09-23 14:15 ` Namhyung Kim
2020-09-23 20:19 ` Jiri Olsa
2020-09-23 20:19 ` Jiri Olsa
2020-09-24 14:36 ` Namhyung Kim
2020-09-24 14:36 ` Namhyung Kim
2020-09-25 21:01 ` Jiri Olsa
2020-09-25 21:01 ` Jiri Olsa
2020-10-02 8:59 ` Jiri Olsa
2020-10-02 8:59 ` Jiri Olsa
2020-10-06 6:51 ` Song Bao Hua (Barry Song)
2020-10-06 6:51 ` Song Bao Hua (Barry Song)
2020-09-22 3:13 ` [PATCH 2/2] perf stat: Unbreak perf stat with " Wei Li
2020-09-22 3:13 ` Wei Li
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