Commit 4cf7a136 authored by Namhyung Kim's avatar Namhyung Kim Committed by Ingo Molnar
Browse files

perf/core: Save the dynamic parts of sample data size 



The perf sample data can be divided into parts.  The event->header_size
and event->id_header_size keep the static part of the sample data which
is determined by the sample_type flags.

But other parts like CALLCHAIN and BRANCH_STACK are changing dynamically
so it needs to see the actual data.  In preparation of handling repeated
calls for perf_prepare_sample(), it can save the dynamic size to the
perf sample data to avoid the duplicate work.

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Tested-by: default avatarJiri Olsa <jolsa@kernel.org>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Acked-by: default avatarSong Liu <song@kernel.org>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230118060559.615653-2-namhyung@kernel.org
parent 65adf3a5

include/linux/perf_event.h

+2 −0
Original line number Diff line number Diff line
@@ -1103,6 +1103,7 @@ struct perf_sample_data { 
	 */

	u64				sample_flags;

	u64				period;

	u64				dyn_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->dyn_size = 0;



	if (addr) {

		data->addr = addr;

kernel/events/core.c

+10 −7
Original line number Diff line number Diff line
@@ -7586,7 +7586,7 @@ void perf_prepare_sample(struct perf_event_header *header, 


		size += data->callchain->nr;



		header->size += size * sizeof(u64);

		data->dyn_size += size * sizeof(u64);

	}



	if (sample_type & PERF_SAMPLE_RAW) {
@@ -7612,7 +7612,7 @@ void perf_prepare_sample(struct perf_event_header *header, 
			data->raw = NULL;

		}



		header->size += size;

		data->dyn_size += size;

	}



	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
@@ -7624,7 +7624,7 @@ void perf_prepare_sample(struct perf_event_header *header, 
			size += data->br_stack->nr

			      * sizeof(struct perf_branch_entry);

		}

		header->size += size;

		data->dyn_size += size;

	}



	if (sample_type & (PERF_SAMPLE_REGS_USER | PERF_SAMPLE_STACK_USER))
@@ -7639,7 +7639,7 @@ void perf_prepare_sample(struct perf_event_header *header, 
			size += hweight64(mask) * sizeof(u64);

		}



		header->size += size;

		data->dyn_size += size;

	}



	if (sample_type & PERF_SAMPLE_STACK_USER) {
@@ -7664,7 +7664,7 @@ void perf_prepare_sample(struct perf_event_header *header, 
			size += sizeof(u64) + stack_size;



		data->stack_user_size = stack_size;

		header->size += size;

		data->dyn_size += size;

	}



	if (filtered_sample_type & PERF_SAMPLE_WEIGHT_TYPE)
@@ -7693,7 +7693,7 @@ void perf_prepare_sample(struct perf_event_header *header, 
			size += hweight64(mask) * sizeof(u64);

		}



		header->size += size;

		data->dyn_size += size;

	}



	if (sample_type & PERF_SAMPLE_PHYS_ADDR &&
@@ -7738,8 +7738,11 @@ void perf_prepare_sample(struct perf_event_header *header, 
		size = perf_prepare_sample_aux(event, data, size);



		WARN_ON_ONCE(size + header->size > U16_MAX);

		header->size += size;

		data->dyn_size += size + sizeof(u64); /* size above */

	}



	header->size += data->dyn_size;



	/*

	 * If you're adding more sample types here, you likely need to do

	 * something about the overflowing header::size, like repurpose the