From: Peter Zijlstra <peterz@infradead.org>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@kernel.org>,
Kan Liang <kan.liang@linux.intel.com>,
Ravi Bangoria <ravi.bangoria@amd.com>,
bpf@vger.kernel.org
Subject: Re: [PATCH 2/3] perf/core: Set data->sample_flags in perf_prepare_sample()
Date: Tue, 10 Jan 2023 11:55:41 +0100 [thread overview]
Message-ID: <Y71ELS9GTz0hqaUt@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <Y7x3RUd67smv3EFQ@google.com>
On Mon, Jan 09, 2023 at 12:21:25PM -0800, Namhyung Kim wrote:
> > However; inspired by your next patch; we can do something like so:
> >
> > if (filtered_sample_type & PERF_SAMPLE_CALLCHAIN) {
> > data->callchain = perf_callchain(event, regs);
> > data->sample_flags |= PERF_SAMPLE_CALLCHAIN;
> >
> > data->size += (1 + data->callchain->nr) * sizeof(u64);
> > }
>
> This is fine as long as all other places (like in PMU drivers) set the
> callchain update the sample data size accordingly. If not, we can get
> the callchain but the data size will be wrong.
Good point, maybe add a helper there to ensure that code doesn't
duplicate/diverge?
next prev parent reply other threads:[~2023-01-10 10:56 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-29 20:40 [PATCH 1/3] perf/core: Change the layout of perf_sample_data Namhyung Kim
2022-12-29 20:41 ` [PATCH 2/3] perf/core: Set data->sample_flags in perf_prepare_sample() Namhyung Kim
2023-01-09 12:14 ` Peter Zijlstra
2023-01-09 20:21 ` Namhyung Kim
2023-01-10 10:54 ` Peter Zijlstra
2023-01-10 11:10 ` Ingo Molnar
2023-01-10 19:00 ` Namhyung Kim
2023-01-10 10:55 ` Peter Zijlstra [this message]
2023-01-10 19:01 ` Namhyung Kim
2023-01-10 20:06 ` Namhyung Kim
2023-01-11 12:54 ` Peter Zijlstra
2023-01-11 16:45 ` Peter Zijlstra
2023-01-11 17:59 ` Namhyung Kim
2023-01-09 17:02 ` [tip: perf/core] " tip-bot2 for Namhyung Kim
2022-12-29 20:41 ` [PATCH 3/3] perf/core: Save calculated sample data size Namhyung Kim
2023-01-09 17:02 ` [tip: perf/core] " tip-bot2 for Namhyung Kim
2023-01-09 17:02 ` [tip: perf/core] perf/core: Change the layout of perf_sample_data tip-bot2 for Namhyung Kim
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