Messages in this thread | | | Date | Wed, 7 Mar 2018 10:58:54 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] perf mmap: Discard head in overwrite_rb_find_range |
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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?
- 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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