Hi jirka, On 2018/3/7 18:21, Jiri Olsa wrote: > On Tue, Mar 06, 2018 at 07:44:23PM +0800, Yisheng Xie wrote: >> In overwrite mode, start will be set to head in perf_mmap__read_init. >> Therefore, it is no need to set the start one more in >> overwrite_rb_find_range and *start can be used as head instead of >> passing head to overwrite_rb_find_range. > > it conflicts a little with recent cleanup from Kan Liang,, > https://marc.info/?t=152035082800001&r=1&w=2 > > otherwise it looks ok to me >
I can send the next version based on Kan's patch after his patches are in the tree. Thanks Yisheng > jirka > >> >> Signed-off-by: Yisheng Xie <xieyishe...@huawei.com> >> --- >> tools/perf/util/mmap.c | 15 +++++++-------- >> 1 file changed, 7 insertions(+), 8 deletions(-) >> >> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c >> index 91531a7..6751ac9 100644 >> --- a/tools/perf/util/mmap.c >> +++ b/tools/perf/util/mmap.c >> @@ -223,19 +223,18 @@ 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; >> @@ -287,7 +286,7 @@ int perf_mmap__read_init(struct perf_mmap *md, bool >> overwrite, >> * 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, startp, endp)) >> + if (overwrite_rb_find_range(data, md->mask, startp, endp)) >> return -EINVAL; >> } >> >> -- >> 1.7.12.4 >> > > . >