Commit 04391deb authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

perf evlist: Steal mmap reading routine from 'perf top' 



Will be used in the upcoming 'perf test' entry for the evlist mmap
routines.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 98d77b78

tools/perf/builtin-top.c

+3 −53
Original line number Diff line number Diff line
@@ -1100,67 +1100,17 @@ static void event__process_sample(const event_t *self, 


static void perf_session__mmap_read_cpu(struct perf_session *self, int cpu)

{

	struct perf_mmap *md = &evsel_list->mmap[cpu];

	unsigned int head = perf_mmap__read_head(md);

	unsigned int old = md->prev;

	unsigned char *data = md->base + page_size;

	struct sample_data sample;

	int diff;



	/*

	 * If we're further behind than half the buffer, there's a chance

	 * the writer will bite our tail and mess up the samples under us.

	 *

	 * If we somehow ended up ahead of the head, we got messed up.

	 *

	 * In either case, truncate and restart at head.

	 */

	diff = head - old;

	if (diff > md->mask / 2 || diff < 0) {

		fprintf(stderr, "WARNING: failed to keep up with mmap data.\n");



		/*

		 * head points to a known good entry, start there.

		 */

		old = head;

	}



	for (; old != head;) {

		event_t *event = (event_t *)&data[old & md->mask];



		event_t event_copy;



		size_t size = event->header.size;



		/*

		 * Event straddles the mmap boundary -- header should always

		 * be inside due to u64 alignment of output.

		 */

		if ((old & md->mask) + size != ((old + size) & md->mask)) {

			unsigned int offset = old;

			unsigned int len = min(sizeof(*event), size), cpy;

			void *dst = &event_copy;



			do {

				cpy = min(md->mask + 1 - (offset & md->mask), len);

				memcpy(dst, &data[offset & md->mask], cpy);

				offset += cpy;

				dst += cpy;

				len -= cpy;

			} while (len);



			event = &event_copy;

		}

	event_t *event;



	while ((event = perf_evlist__read_on_cpu(evsel_list, cpu)) != NULL) {

		event__parse_sample(event, self, &sample);



		if (event->header.type == PERF_RECORD_SAMPLE)

			event__process_sample(event, &sample, self);

		else

			event__process(event, &sample, self);

		old += size;

	}



	md->prev = old;

}



static void perf_session__mmap_read(struct perf_session *self)

tools/perf/util/evlist.c

+62 −0
Original line number Diff line number Diff line
@@ -95,3 +95,65 @@ struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id) 
			return sid->evsel;

	return NULL;

}



event_t *perf_evlist__read_on_cpu(struct perf_evlist *evlist, int cpu)

{

	/* XXX Move this to perf.c, making it generally available */

	unsigned int page_size = sysconf(_SC_PAGE_SIZE);

	struct perf_mmap *md = &evlist->mmap[cpu];

	unsigned int head = perf_mmap__read_head(md);

	unsigned int old = md->prev;

	unsigned char *data = md->base + page_size;

	event_t *event = NULL;

	int diff;



	/*

	 * If we're further behind than half the buffer, there's a chance

	 * the writer will bite our tail and mess up the samples under us.

	 *

	 * If we somehow ended up ahead of the head, we got messed up.

	 *

	 * In either case, truncate and restart at head.

	 */

	diff = head - old;

	if (diff > md->mask / 2 || diff < 0) {

		fprintf(stderr, "WARNING: failed to keep up with mmap data.\n");



		/*

		 * head points to a known good entry, start there.

		 */

		old = head;

	}



	if (old != head) {

		size_t size;



		event = (event_t *)&data[old & md->mask];

		size = event->header.size;



		/*

		 * Event straddles the mmap boundary -- header should always

		 * be inside due to u64 alignment of output.

		 */

		if ((old & md->mask) + size != ((old + size) & md->mask)) {

			unsigned int offset = old;

			unsigned int len = min(sizeof(*event), size), cpy;

			void *dst = &evlist->event_copy;



			do {

				cpy = min(md->mask + 1 - (offset & md->mask), len);

				memcpy(dst, &data[offset & md->mask], cpy);

				offset += cpy;

				dst += cpy;

				len -= cpy;

			} while (len);



			event = &evlist->event_copy;

		}



		old += size;

	}



	md->prev = old;

	return event;

}

tools/perf/util/evlist.h

+4 −0
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 


#include <linux/list.h>

#include "../perf.h"

#include "event.h"



struct pollfd;
@@ -15,6 +16,7 @@ struct perf_evlist { 
	int		 nr_entries;

	int		 nr_fds;

	int		 mmap_len;

	event_t		 event_copy;

	struct perf_mmap *mmap;

	struct pollfd	 *pollfd;

};
@@ -32,4 +34,6 @@ void perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd); 


struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id);



event_t *perf_evlist__read_on_cpu(struct perf_evlist *self, int cpu);



#endif /* __PERF_EVLIST_H */

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