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Message-ID: <CAM9d7cjUAOhME8jf=sRbzWFcaGssaXRhhL9rwkBxSLjdPaZg8w@mail.gmail.com>
Date: Tue, 17 Jan 2023 00:12:57 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Jiri Olsa <olsajiri@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
LKML <linux-kernel@...r.kernel.org>, Song Liu <song@...nel.org>,
bpf@...r.kernel.org
Subject: Re: [PATCHSET 0/8] perf/core: Prepare sample data for BPF
Hi Jiri,
On Fri, Jan 13, 2023 at 5:26 AM Jiri Olsa <olsajiri@...il.com> wrote:
>
> On Thu, Jan 12, 2023 at 01:40:07PM -0800, Namhyung Kim wrote:
> > Hello,
> >
> > The perf_prepare_sample() is to fill the perf sample data and update the
> > header info before sending it to the ring buffer. But we want to use it
> > for BPF overflow handler so that it can access the sample data to filter
> > relevant ones.
> >
> > Changes in v2)
> > * the layout change is merged
> > * reduce branches using __cond_set (PeterZ)
> > * add helpers to set dynamic sample data (PeterZ)
> > * introduce perf_prepare_header() (PeterZ)
> > * call perf_prepare_sample() before bpf_overflow_handler unconditionally
> >
> > This means the perf_prepare_handler() can be called more than once. To
> > avoid duplicate work, use the data->sample_flags and save the data size.
> >
> > I also added a few of helpers to set those information accordingly.
> > But it looks some fields like REGS_USER, STACK_USER and AUX are saved in
> > the perf_prepare_sample() so I didn't add the helpers for them.
> >
> > After than we can just check the filtered_sample_type flags begin zero
> > to determine if it has more work. In that case, it needs to update the
> > data->type since it's possible to miss when PMU driver sets all required
> > sample flags before calling perf_prepare_sample().
> >
> > The code is also available at 'perf/prepare-sample-v2' branch in
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
> >
> > Thanks,
> > Namhyung
> >
> >
> > Cc: Song Liu <song@...nel.org>
> > Cc: bpf@...r.kernel.org
> >
> >
> > Namhyung Kim (8):
> > perf/core: Save the dynamic parts of sample data size
> > perf/core: Add perf_sample_save_callchain() helper
> > perf/core: Add perf_sample_save_raw_data() helper
> > perf/core: Add perf_sample_save_brstack() helper
> > perf/core: Set data->sample_flags in perf_prepare_sample()
> > perf/core: Do not pass header for sample id init
> > perf/core: Introduce perf_prepare_header()
> > perf/core: Call perf_prepare_sample() before running BPF
>
> lgtm, I ran the bpf selftests on top of that and it's ok
Thanks for your review. I'll add your Acked-by and Tested-by
in the v3. :)
Thanks,
Namhyung
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