diff options
| author | Yisheng Xie <xieyisheng1@huawei.com> | 2018-03-13 20:31:13 +0800 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-03-16 16:33:05 -0300 |
| commit | 699db111058798bcc9f92a93767062905a561bef (patch) | |
| tree | 0b2615bd90f2d98d7e30df2ad3a8837f8e0bd6ba /tools | |
| parent | 9749adc3b2a23c91b2eda8758ff0c650d731aa2f (diff) | |
| download | linux-699db111058798bcc9f92a93767062905a561bef.tar.bz2 | |
perf mmap: Discard head in overwrite_rb_find_range()
In overwrite mode, start will be set to head in perf_mmap__read_init().
Therefore, there is no need to set the start one more time in
overwrite_rb_find_range() and *start can be used as head instead of
passing head to overwrite_rb_find_range().
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1520944274-37001-1-git-send-email-xieyisheng1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/perf/util/mmap.c | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c index 074c4fd3b67e..38ca3ffb9d61 100644 --- a/tools/perf/util/mmap.c +++ b/tools/perf/util/mmap.c @@ -199,19 +199,18 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd) return 0; } -static int overwrite_rb_find_range(void *buf, int mask, u64 head, u64 *start, u64 *end) +static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end) { struct perf_event_header *pheader; - u64 evt_head = head; + u64 evt_head = *start; int size = mask + 1; - pr_debug2("overwrite_rb_find_range: buf=%p, head=%"PRIx64"\n", buf, head); - pheader = (struct perf_event_header *)(buf + (head & mask)); - *start = head; + pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start); + pheader = (struct perf_event_header *)(buf + (*start & mask)); while (true) { - if (evt_head - head >= (unsigned int)size) { + if (evt_head - *start >= (unsigned int)size) { pr_debug("Finished reading overwrite ring buffer: rewind\n"); - if (evt_head - head > (unsigned int)size) + if (evt_head - *start > (unsigned int)size) evt_head -= pheader->size; *end = evt_head; return 0; @@ -262,7 +261,7 @@ int perf_mmap__read_init(struct perf_mmap *md) * Backward ring buffer is full. We still have a chance to read * most of data from it. */ - if (overwrite_rb_find_range(data, md->mask, head, &md->start, &md->end)) + if (overwrite_rb_find_range(data, md->mask, &md->start, &md->end)) return -EINVAL; } |