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Message-ID: <ZqqAkcz4xOto_sK5@google.com>
Date: Wed, 31 Jul 2024 11:21:05 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Kan Liang <kan.liang@...ux.intel.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH v1] perf inject: Fix leader sampling inserting additional
samples
Hi Ian,
On Mon, Jul 29, 2024 at 03:06:20PM -0700, Ian Rogers wrote:
> The processing of leader samples would turn an individual sample with
> a group of read values into multiple samples. Perf inject would pass
> through the additional samples increasing the output data file size:
>
> ```
> $ perf record -g -e "{instructions,cycles}:S" -o perf.orig.data true
> $ perf script -D -i perf.orig.data | sed -e 's/perf.orig.data/perf.data/g' > orig.txt
> $ perf inject -i perf.orig.data -o perf.new.data
> $ perf script -D -i perf.new.data | sed -e 's/perf.new.data/perf.data/g' > new.txt
> $ diff -u orig.txt new.txt
> --- orig.txt 2024-07-29 14:29:40.606576769 -0700
> +++ new.txt 2024-07-29 14:30:04.142737434 -0700
> ...
> -0xc550@...f.data [0x30]: event: 3
> +0xc550@...f.data [0xd0]: event: 9
> +.
> +. ... raw event: size 208 bytes
> +. 0000: 09 00 00 00 01 00 d0 00 fc 72 01 86 ff ff ff ff .........r......
> +. 0010: 74 7d 2c 00 74 7d 2c 00 fb c3 79 f9 ba d5 05 00 t},.t},...y.....
> +. 0020: e6 cb 1a 00 00 00 00 00 01 00 00 00 00 00 00 00 ................
> +. 0030: 02 00 00 00 00 00 00 00 76 01 00 00 00 00 00 00 ........v.......
> +. 0040: e6 cb 1a 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> +. 0050: 62 18 00 00 00 00 00 00 f6 cb 1a 00 00 00 00 00 b...............
> +. 0060: 00 00 00 00 00 00 00 00 0c 00 00 00 00 00 00 00 ................
> +. 0070: 80 ff ff ff ff ff ff ff fc 72 01 86 ff ff ff ff .........r......
> +. 0080: f3 0e 6e 85 ff ff ff ff 0c cb 7f 85 ff ff ff ff ..n.............
> +. 0090: bc f2 87 85 ff ff ff ff 44 af 7f 85 ff ff ff ff ........D.......
> +. 00a0: bd be 7f 85 ff ff ff ff 26 d0 7f 85 ff ff ff ff ........&.......
> +. 00b0: 6d a4 ff 85 ff ff ff ff ea 00 20 86 ff ff ff ff m......... .....
> +. 00c0: 00 fe ff ff ff ff ff ff 57 14 4f 43 fc 7e 00 00 ........W.OC.~..
> +
> +1642373909693435 0xc550 [0xd0]: PERF_RECORD_SAMPLE(IP, 0x1): 2915700/2915700: 0xffffffff860172fc period: 1 addr: 0
> +... FP chain: nr:12
> +..... 0: ffffffffffffff80
> +..... 1: ffffffff860172fc
> +..... 2: ffffffff856e0ef3
> +..... 3: ffffffff857fcb0c
> +..... 4: ffffffff8587f2bc
> +..... 5: ffffffff857faf44
> +..... 6: ffffffff857fbebd
> +..... 7: ffffffff857fd026
> +..... 8: ffffffff85ffa46d
> +..... 9: ffffffff862000ea
> +..... 10: fffffffffffffe00
> +..... 11: 00007efc434f1457
> +... sample_read:
> +.... group nr 2
> +..... id 00000000001acbe6, value 0000000000000176, lost 0
> +..... id 00000000001acbf6, value 0000000000001862, lost 0
> +
> +0xc620@...f.data [0x30]: event: 3
> ...
> ```
>
> This behavior is incorrect as in the case above perf inject should
> have done nothing. Fix this behavior by disabling separating samples
> for a tool that requests it. Only request this for `perf inject` so as
> to not affect other perf tools. With the patch and the test above
> there are no differences between the orig.txt and new.txt.
>
> Fixes: e4caec0d1af3 ("perf evsel: Add PERF_SAMPLE_READ sample related processing")
> Signed-off-by: Ian Rogers <irogers@...gle.com>
Acked-by: Namhyung Kim <namhyung@...nel.org>
Thanks,
Namhyung
> ---
> tools/perf/builtin-inject.c | 1 +
> tools/perf/util/session.c | 3 +++
> tools/perf/util/tool.h | 1 +
> 3 files changed, 5 insertions(+)
>
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index a212678d47be..c80fb0f60e61 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -2204,6 +2204,7 @@ int cmd_inject(int argc, const char **argv)
> .finished_init = perf_event__repipe_op2_synth,
> .compressed = perf_event__repipe_op4_synth,
> .auxtrace = perf_event__repipe_auxtrace,
> + .dont_split_sample_group = true,
> },
> .input_name = "-",
> .samples = LIST_HEAD_INIT(inject.samples),
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 5596bed1b8c8..080242c69196 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -1511,6 +1511,9 @@ static int deliver_sample_group(struct evlist *evlist,
> int ret = -EINVAL;
> struct sample_read_value *v = sample->read.group.values;
>
> + if (tool->dont_split_sample_group)
> + return deliver_sample_value(evlist, tool, event, sample, v, machine);
> +
> sample_read_group__for_each(v, sample->read.group.nr, read_format) {
> ret = deliver_sample_value(evlist, tool, event, sample, v,
> machine);
> diff --git a/tools/perf/util/tool.h b/tools/perf/util/tool.h
> index c957fb849ac6..62bbc9cec151 100644
> --- a/tools/perf/util/tool.h
> +++ b/tools/perf/util/tool.h
> @@ -85,6 +85,7 @@ struct perf_tool {
> bool namespace_events;
> bool cgroup_events;
> bool no_warn;
> + bool dont_split_sample_group;
> enum show_feature_header show_feat_hdr;
> };
>
> --
> 2.46.0.rc1.232.g9752f9e123-goog
>
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