The following commit has been merged into the perf/core branch of tip: Commit-ID: 0ecc518e5c1a83fbfc6262d20d0df289eafc2207 Gitweb: https://git.kernel.org/tip/0ecc518e5c1a83fbfc6262d20d0df289eafc2207 Author: Namhyung Kim <namhyung@xxxxxxxxxx> AuthorDate: Thu, 29 Dec 2022 12:41:01 -08:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Mon, 09 Jan 2023 12:22:09 +01:00 perf/core: Save calculated sample data size To avoid duplicate work in perf_prepare_sample(), save the final header size in data->saved_size. It's initialized to 0 and set to an actual value at the end of perf_prepare_sample(). If it sees a non-zero value that means it's the second time of the call and it knows the sample data is populated already. So update the header size with the data->saved_size and bail out. Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Link: https://lore.kernel.org/r/20221229204101.1099430-3-namhyung@xxxxxxxxxx --- include/linux/perf_event.h | 2 ++ kernel/events/core.c | 11 +++++++++++ 2 files changed, 13 insertions(+) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 03949d0..656b6ea 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1103,6 +1103,7 @@ struct perf_sample_data { */ u64 sample_flags; u64 period; + u64 saved_size; /* * Fields commonly set by __perf_event_header__init_id(), @@ -1158,6 +1159,7 @@ static inline void perf_sample_data_init(struct perf_sample_data *data, /* remaining struct members initialized in perf_prepare_sample() */ data->sample_flags = PERF_SAMPLE_PERIOD; data->period = period; + data->saved_size = 0; if (addr) { data->addr = addr; diff --git a/kernel/events/core.c b/kernel/events/core.c index 70bff8a..dac4d76 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7576,6 +7576,15 @@ void perf_prepare_sample(struct perf_event_header *header, header->misc |= perf_misc_flags(regs); /* + * If it called perf_prepare_sample() already, it set the all data fields + * and recorded the final size to data->saved_size. + */ + if (data->saved_size) { + header->size = data->saved_size; + return; + } + + /* * Clear the sample flags that have already been done by the * PMU driver. */ @@ -7796,6 +7805,8 @@ void perf_prepare_sample(struct perf_event_header *header, * do here next. */ WARN_ON_ONCE(header->size & 7); + + data->saved_size = header->size; } static __always_inline int