Messages in this thread | | | Subject | Re: [PATCH] perf mmap: Discard head in overwrite_rb_find_range | From | Yisheng Xie <> | Date | Thu, 8 Mar 2018 09:05:40 +0800 |
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Hi Arnaldo,
On 2018/3/7 21:58, Arnaldo Carvalho de Melo wrote: > Em Wed, Mar 07, 2018 at 11:21:57AM +0100, Jiri Olsa escreveu: >> 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 > > yeah, wait a while till I push Kan's simplifications and then resubmit, > ok? > Sure, I will wait and resubmit.
Thanks Yisheng
> - Arnaldo > >> jirka >> >>> >>> Signed-off-by: Yisheng Xie <xieyisheng1@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 >>> > > . >
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