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perf mmap: Remove overwrite and check_messup from mmap read

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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: Wang Nan <wangnan0@huawei.com>
Acked-by: Namhyung 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: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Wang Nan
2017-12-03 02:00:41 +00:00
committed by Arnaldo Carvalho de Melo
parent ca6a9a0539
commit 8eb7a1fe31
3 changed files with 6 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
tools/perf/util/evlist.c
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@@ -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 * No need for read-write ring buffer: kernel stop outputting when
* it hit md->prev (perf_mmap__consume()). * 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) union perf_event *perf_evlist__mmap_read_backward(struct perf_evlist *evlist, int idx)

28
tools/perf/util/mmap.c
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@@ -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 */ /* 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) u64 start, u64 end, u64 *prev)
{ {
unsigned char *data = map->base + page_size; unsigned char *data = map->base + page_size;
union perf_event *event = NULL; union perf_event *event = NULL;
int diff = end - start; 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)) { if (diff >= (int)sizeof(event->header)) {
size_t size; size_t size;
@@ -89,7 +69,7 @@ broken_event:
return 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 head;
u64 old = map->prev; 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); 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) 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 else
end = head + map->mask + 1; 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) void perf_mmap__read_catchup(struct perf_mmap *map)

2
tools/perf/util/mmap.h
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@@ -86,7 +86,7 @@ static inline void perf_mmap__write_tail(struct perf_mmap *md, u64 tail)
pc->data_tail = 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); union perf_event *perf_mmap__read_backward(struct perf_mmap *map);
int perf_mmap__push(struct perf_mmap *md, bool backward, int perf_mmap__push(struct perf_mmap *md, bool backward,