Re: [PATCH 1/8] perf sample: Add file_offset field to struct perf_sample

[Ian Rogers]

On Tue, Jun 2, 2026 at 4:57 PM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
>
> From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
>
> Add a file_offset field to struct perf_sample so that event processing
> callbacks can report the byte offset of the problematic event in
> perf.data, letting users cross-reference with 'perf report -D' output.
>
> Set sample.file_offset in perf_session__deliver_event(), which is the
> common entry point for both file mode (mmap'd offset) and pipe mode
> (running byte counter from __perf_session__process_pipe_events).
>
> The assignment is placed after evsel__parse_sample(), which zeroes
> the struct via memset.
>
> Preserve file_offset through the deferred callchain delivery path by
> storing it in struct deferred_event and restoring it after
> evlist__parse_sample() in both evlist__deliver_deferred_callchain()
> and session__flush_deferred_samples().
>
> Subsequent patches will use this field in skip/stop warning messages.
>
> Assisted-by: Claude Opus 4.6 <noreply@xxxxxxxxxxxxx>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/util/sample.h  | 2 ++
>  tools/perf/util/session.c | 5 +++++
>  2 files changed, 7 insertions(+)
>
> diff --git a/tools/perf/util/sample.h b/tools/perf/util/sample.h
> index e556c9b656ea9cd6..c4eae8b2fd06035a 100644
> --- a/tools/perf/util/sample.h
> +++ b/tools/perf/util/sample.h
> @@ -158,6 +158,8 @@ struct perf_sample {
>         u64 code_page_size;
>         /** @cgroup: The sample event PERF_SAMPLE_CGROUP value. */
>         u64 cgroup;
> +       /** @file_offset: Byte offset of this event in the perf.data file. */
> +       u64 file_offset;
>         /** @flags: Extra flag data from auxiliary events like intel-pt. */
>         u32 flags;
>         /** @machine_pid: The guest machine pid derived from the sample id. */
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index e2e821b77766dbfc..7996787d742e32c6 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -1824,6 +1824,7 @@ static int evlist__deliver_sample(struct evlist *evlist, const struct perf_tool
>  struct deferred_event {
>         struct list_head list;
>         union perf_event *event;
> +       u64 file_offset;
>  };
>
>  /*
> @@ -1858,6 +1859,7 @@ static int evlist__deliver_deferred_callchain(struct evlist *evlist,
>                         perf_sample__exit(&orig_sample);
>                         break;
>                 }
> +               orig_sample.file_offset = de->file_offset;
>
>                 if (sample->tid != orig_sample.tid) {
>                         perf_sample__exit(&orig_sample);
> @@ -1906,6 +1908,7 @@ static int session__flush_deferred_samples(struct perf_session *session,
>                         perf_sample__exit(&sample);
>                         break;
>                 }
> +               sample.file_offset = de->file_offset;
>
>                 sample.evsel = evlist__id2evsel(evlist, sample.id);
>                 ret = evlist__deliver_sample(evlist, tool, de->event,
> @@ -1984,6 +1987,7 @@ static int machines__deliver_event(struct machines *machines,
>                                 return -ENOMEM;
>                         }
>                         memcpy(de->event, event, sz);
> +                       de->file_offset = sample->file_offset;
>                         list_add_tail(&de->list, &evlist->deferred_samples);
>                         return 0;
>                 }
> @@ -2126,6 +2130,7 @@ static int perf_session__deliver_event(struct perf_session *session,
>                 pr_err("Can't parse sample, err = %d\n", ret);
>                 goto out;
>         }
> +       sample.file_offset = file_offset;
>         /*
>          * evsel__parse_sample() doesn't populate machine_pid/vcpu,
>          * which are needed by machines__find_for_cpumode() to
> --
> 2.54.0
>