Re: [PATCH 06/35] perf tools: Add perf_event__synthesize_id_sample()

Ian Rogers
2022-07-19T17:11:13Z

On Mon, Jul 11, 2022 at 2:32 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> Add perf_event__synthesize_id_sample() to enable the synthesis of
> ID samples.
>
> This is needed by perf inject. When injecting events from a guest perf.data
> file, there is a possibility that the sample ID numbers conflict. In that
> case, perf_event__synthesize_id_sample() can be used to re-write the ID
> sample.

This is great documentation, it would be nice to capture it with the
function declaration.

Thanks,
Ian

> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
> tools/perf/util/synthetic-events.c | 47 ++++++++++++++++++++++++++++++
> tools/perf/util/synthetic-events.h | 1 +
> 2 files changed, 48 insertions(+)
>
> diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> index fe5db4bf0042..ed9623702f34 100644
> --- a/tools/perf/util/synthetic-events.c
> +++ b/tools/perf/util/synthetic-events.c
> @@ -1712,6 +1712,53 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
> return 0;
> }
>
> +int perf_event__synthesize_id_sample(__u64 *array, u64 type, const struct perf_sample *sample)
> +{
> + __u64 *start = array;
> +
> + /*
> + * used for cross-endian analysis. See git commit 65014ab3
> + * for why this goofiness is needed.
> + */
> + union u64_swap u;
> +
> + if (type & PERF_SAMPLE_TID) {
> + u.val32[0] = sample->pid;
> + u.val32[1] = sample->tid;
> + *array = u.val64;
> + array++;
> + }
> +
> + if (type & PERF_SAMPLE_TIME) {
> + *array = sample->time;
> + array++;
> + }
> +
> + if (type & PERF_SAMPLE_ID) {
> + *array = sample->id;
> + array++;
> + }
> +
> + if (type & PERF_SAMPLE_STREAM_ID) {
> + *array = sample->stream_id;
> + array++;
> + }
> +
> + if (type & PERF_SAMPLE_CPU) {
> + u.val32[0] = sample->cpu;
> + u.val32[1] = 0;
> + *array = u.val64;
> + array++;
> + }
> +
> + if (type & PERF_SAMPLE_IDENTIFIER) {
> + *array = sample->id;
> + array++;
> + }
> +
> + return (void *)array - (void *)start;
> +}
> +
> int perf_event__synthesize_id_index(struct perf_tool *tool, perf_event__handler_t process,
> struct evlist *evlist, struct machine *machine)
> {
> diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
> index 78a0450db164..b136ec3ec95d 100644
> --- a/tools/perf/util/synthetic-events.h
> +++ b/tools/perf/util/synthetic-events.h
> @@ -55,6 +55,7 @@ int perf_event__synthesize_extra_attr(struct perf_tool *tool, struct evlist *evs
> int perf_event__synthesize_extra_kmaps(struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
> int perf_event__synthesize_features(struct perf_tool *tool, struct perf_session *session, struct evlist *evlist, perf_event__handler_t process);
> int perf_event__synthesize_id_index(struct perf_tool *tool, perf_event__handler_t process, struct evlist *evlist, struct machine *machine);
> +int perf_event__synthesize_id_sample(__u64 *array, u64 type, const struct perf_sample *sample);
> int perf_event__synthesize_kernel_mmap(struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
> int perf_event__synthesize_mmap_events(struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine, bool mmap_data);
> int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
> --
> 2.25.1
>