> On Thu, Dec 21, 2017 at 10:08:44AM -0800, [email protected] wrote: > > From: Kan Liang <[email protected]> > > > > The perf record has specific codes to calculate the ringbuffer > > position for both overwrite and non-overwrite mode. > > The perf top will support both modes later. > > It is useful to make the specific codes generic. > > > > Introduce a new interface perf_mmap__read_init() to find ringbuffer > > position. > > Add a check for map->refcnt in perf_mmap__read_init(). > > 'size' is needed for both perf_mmap__read_init() and perf_mmap__push(). > > Have to calculate in each function. > > it's 2 separate changes then plus 1 not mentioned in changelog.. > could you please split this into separate patches: > > - Introduce a new interface perf_mmap__read_init ... > - Add a check for map->refcnt in perf_mmap__read_init > - add new EAGAIN return value logic >
Thanks for the comments, Jirka. I will split the patch accordingly in V4. Thanks, Kan > thanks, > jirka > > > > > Signed-off-by: Kan Liang <[email protected]> > > --- > > tools/perf/util/mmap.c | 62 > > ++++++++++++++++++++++++++++++++++---------------- > > tools/perf/util/mmap.h | 2 ++ > > 2 files changed, 45 insertions(+), 19 deletions(-) > > > > diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c index > > 05076e6..3fd4f3c 100644 > > --- a/tools/perf/util/mmap.c > > +++ b/tools/perf/util/mmap.c > > @@ -267,41 +267,65 @@ static int overwrite_rb_find_range(void *buf, int > mask, u64 head, u64 *start, u6 > > return -1; > > } > > > > -int perf_mmap__push(struct perf_mmap *md, bool overwrite, > > - void *to, int push(void *to, void *buf, size_t size)) > > +/* > > + * Report the start and end of the available data in ringbuffer */ > > +int perf_mmap__read_init(struct perf_mmap *map, bool overwrite, > > + u64 *start, u64 *end) > > { > > - u64 head = perf_mmap__read_head(md); > > - u64 old = md->prev; > > - u64 end = head, start = old; > > - unsigned char *data = md->base + page_size; > > + u64 head = perf_mmap__read_head(map); > > + u64 old = map->prev; > > + unsigned char *data = map->base + page_size; > > unsigned long size; > > - void *buf; > > - int rc = 0; > > > > - start = overwrite ? head : old; > > - end = overwrite ? old : head; > > + /* > > + * Check if event was unmapped due to a POLLHUP/POLLERR. > > + */ > > + if (!refcount_read(&map->refcnt)) > > + return -EINVAL; > > > > - if (start == end) > > - return 0; > > + *start = overwrite ? head : old; > > + *end = overwrite ? old : head; > > > > - size = end - start; > > - if (size > (unsigned long)(md->mask) + 1) { > > + if (*start == *end) > > + return -EAGAIN; > > + > > + size = *end - *start; > > + if (size > (unsigned long)(map->mask) + 1) { > > if (!overwrite) { > > WARN_ONCE(1, "failed to keep up with mmap data. > (warn only > > once)\n"); > > > > - md->prev = head; > > - perf_mmap__consume(md, overwrite); > > - return 0; > > + map->prev = head; > > + perf_mmap__consume(map, overwrite); > > + return -EAGAIN; > > } > > > > /* > > * 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, &start, > &end)) > > - return -1; > > + if (overwrite_rb_find_range(data, map->mask, head, start, > end)) > > + return -EINVAL; > > } > > > > + return 0; > > +} > > + > > +int perf_mmap__push(struct perf_mmap *md, bool overwrite, > > + void *to, int push(void *to, void *buf, size_t size)) { > > + u64 head = perf_mmap__read_head(md); > > + u64 end, start; > > + unsigned char *data = md->base + page_size; > > + unsigned long size; > > + void *buf; > > + int rc; > > + > > + rc = perf_mmap__read_init(md, overwrite, &start, &end); > > + if (rc < 0) > > + return (rc == -EAGAIN) ? 0 : -1; > > + > > + size = end - start; > > if ((start & md->mask) + size != (end & md->mask)) { > > buf = &data[start & md->mask]; > > size = md->mask + 1 - (start & md->mask); diff --git > > a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h index > > d640273..abe9b9f 100644 > > --- a/tools/perf/util/mmap.h > > +++ b/tools/perf/util/mmap.h > > @@ -94,4 +94,6 @@ int perf_mmap__push(struct perf_mmap *md, bool > > backward, > > > > size_t perf_mmap__mmap_len(struct perf_mmap *map); > > > > +int perf_mmap__read_init(struct perf_mmap *map, bool overwrite, > > + u64 *start, u64 *end); > > #endif /*__PERF_MMAP_H */ > > -- > > 2.5.5 > >
