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References: <20230112214015.1014857-1-namhyung@kernel.org> <20230112214015.1014857-2-namhyung@kernel.org>
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From:   Song Liu <song@kernel.org>
Date:   Fri, 13 Jan 2023 12:44:23 -0800
Message-ID: <CAPhsuW4s1dz0nAgqLABB4rHY140GwoTQNst78Sye+VVqgfHhyw@mail.gmail.com>
Subject: Re: [PATCH 1/8] perf/core: Save the dynamic parts of sample data size
To:     Namhyung Kim <namhyung@kernel.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Thu, Jan 12, 2023 at 1:40 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> The perf sample data can be divided into parts.  The event->header_size
> and event->id_header_size keep the static part of the sample data which
> is determined by the sample_type flags.
>
> But other parts like CALLCHAIN and BRANCH_STACK are changing dynamically
> so it needs to see the actual data.  In preparation of handling repeated
> calls for perf_prepare_sample(), it can save the dynamic size to the
> perf sample data to avoid the duplicate work.
>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Acked-by: Song Liu <song@kernel.org>