Commit-ID: 8eb7a1fe31612fd3e8ae8042dd2ebaf7575504cb Gitweb: https://git.kernel.org/tip/8eb7a1fe31612fd3e8ae8042dd2ebaf7575504cb Author: Wang Nan <wangn...@huawei.com> AuthorDate: Sun, 3 Dec 2017 02:00:41 +0000 Committer: Arnaldo Carvalho de Melo <a...@redhat.com> CommitDate: Tue, 5 Dec 2017 15:43:54 -0300
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: Wang Nan <wangn...@huawei.com> Acked-by: Namhyung Kim <namhy...@kernel.org> Cc: Jiri Olsa <jo...@redhat.com> Cc: Kan Liang <kan.li...@intel.com> Link: http://lkml.kernel.org/r/20171203020044.81680-6-wangn...@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> --- tools/perf/util/evlist.c | 2 +- tools/perf/util/mmap.c | 28 ++++------------------------ tools/perf/util/mmap.h | 2 +- 3 files changed, 6 insertions(+), 26 deletions(-) diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index a59134f..68c1f95 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -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) diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c index 703ed41..3f262e7 100644 --- a/tools/perf/util/mmap.c +++ b/tools/perf/util/mmap.c @@ -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) diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h index 2c3d291..d640273 100644 --- a/tools/perf/util/mmap.h +++ b/tools/perf/util/mmap.h @@ -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,
