Commit 8eb7a1fe authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
Browse files

perf mmap: Remove overwrite and check_messup from mmap read 



All perf_mmap__read_forward() read from read-write ring buffer, so no
need check_messup. Reading from backward ring buffer doesn't require
check_messup because it never mess up. Cleanup arguments lists.

Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Link: http://lkml.kernel.org/r/20171203020044.81680-6-wangnan0@huawei.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent ca6a9a05

tools/perf/util/evlist.c

+1 −1
Original line number Diff line number Diff line
@@ -711,7 +711,7 @@ union perf_event *perf_evlist__mmap_read_forward(struct perf_evlist *evlist, int 
	 * No need for read-write ring buffer: kernel stop outputting when

	 * it hit md->prev (perf_mmap__consume()).

	 */

	return perf_mmap__read_forward(md, false);

	return perf_mmap__read_forward(md);

}



union perf_event *perf_evlist__mmap_read_backward(struct perf_evlist *evlist, int idx)

tools/perf/util/mmap.c

+4 −24
Original line number Diff line number Diff line
@@ -21,33 +21,13 @@ size_t perf_mmap__mmap_len(struct perf_mmap *map) 
}



/* When check_messup is true, 'end' must points to a good entry */

static union perf_event *perf_mmap__read(struct perf_mmap *map, bool check_messup,

static union perf_event *perf_mmap__read(struct perf_mmap *map,

					 u64 start, u64 end, u64 *prev)

{

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

	union perf_event *event = NULL;

	int diff = end - start;



	if (check_messup) {

		/*

		 * 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 'end', we got messed up.

		 *

		 * In either case, truncate and restart at 'end'.

		 */

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

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



			/*

			 * 'end' points to a known good entry, start there.

			 */

			start = end;

			diff = 0;

		}

	}



	if (diff >= (int)sizeof(event->header)) {

		size_t size;
@@ -89,7 +69,7 @@ broken_event: 
	return event;

}



union perf_event *perf_mmap__read_forward(struct perf_mmap *map, bool check_messup)

union perf_event *perf_mmap__read_forward(struct perf_mmap *map)

{

	u64 head;

	u64 old = map->prev;
@@ -102,7 +82,7 @@ union perf_event *perf_mmap__read_forward(struct perf_mmap *map, bool check_mess 


	head = perf_mmap__read_head(map);



	return perf_mmap__read(map, check_messup, old, head, &map->prev);

	return perf_mmap__read(map, old, head, &map->prev);

}



union perf_event *perf_mmap__read_backward(struct perf_mmap *map)
@@ -138,7 +118,7 @@ union perf_event *perf_mmap__read_backward(struct perf_mmap *map) 
	else

		end = head + map->mask + 1;



	return perf_mmap__read(map, false, start, end, &map->prev);

	return perf_mmap__read(map, start, end, &map->prev);

}



void perf_mmap__read_catchup(struct perf_mmap *map)

tools/perf/util/mmap.h

+1 −1
Original line number Diff line number Diff line
@@ -86,7 +86,7 @@ static inline void perf_mmap__write_tail(struct perf_mmap *md, u64 tail) 
	pc->data_tail = tail;

}



union perf_event *perf_mmap__read_forward(struct perf_mmap *map, bool check_messup);

union perf_event *perf_mmap__read_forward(struct perf_mmap *map);

union perf_event *perf_mmap__read_backward(struct perf_mmap *map);



int perf_mmap__push(struct perf_mmap *md, bool backward,

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