From 7bb45972952db9298fe5cc440160dcad1a66bfbc Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Thu, 18 Jan 2018 13:26:23 -0800 Subject: [PATCH] perf mmap: Introduce perf_mmap__read_event() Except for 'perf record', the other perf tools read events one by one from the ring buffer using perf_mmap__read_forward(). But it only supports non-overwrite mode. Introduce perf_mmap__read_event() to support both non-overwrite and overwrite mode. Usage: perf_mmap__read_init() while(event = perf_mmap__read_event()) { //process the event perf_mmap__consume() } perf_mmap__read_done() It cannot use perf_mmap__read_backward(). Because it always reads the stale buffer which is already processed. Furthermore, the forward and backward concepts have been removed. The perf_mmap__read_backward() will be replaced and discarded later. Signed-off-by: Kan Liang Acked-by: Jiri Olsa Cc: Andi Kleen Cc: Jin Yao Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Wang Nan Link: http://lkml.kernel.org/r/1516310792-208685-9-git-send-email-kan.liang@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/mmap.c | 39 +++++++++++++++++++++++++++++++++++++++ tools/perf/util/mmap.h | 4 ++++ 2 files changed, 43 insertions(+) diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c index 4f59eaefc706..f804926778b7 100644 --- a/tools/perf/util/mmap.c +++ b/tools/perf/util/mmap.c @@ -113,6 +113,45 @@ union perf_event *perf_mmap__read_backward(struct perf_mmap *map) return perf_mmap__read(map, &map->prev, end); } +/* + * Read event from ring buffer one by one. + * Return one event for each call. + * + * Usage: + * perf_mmap__read_init() + * while(event = perf_mmap__read_event()) { + * //process the event + * perf_mmap__consume() + * } + * perf_mmap__read_done() + */ +union perf_event *perf_mmap__read_event(struct perf_mmap *map, + bool overwrite, + u64 *startp, u64 end) +{ + union perf_event *event; + + /* + * Check if event was unmapped due to a POLLHUP/POLLERR. + */ + if (!refcount_read(&map->refcnt)) + return NULL; + + if (startp == NULL) + return NULL; + + /* non-overwirte doesn't pause the ringbuffer */ + if (!overwrite) + end = perf_mmap__read_head(map); + + event = perf_mmap__read(map, startp, end); + + if (!overwrite) + map->prev = *startp; + + return event; +} + void perf_mmap__read_catchup(struct perf_mmap *map) { u64 head; diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h index 95549d4af943..28718543dd42 100644 --- a/tools/perf/util/mmap.h +++ b/tools/perf/util/mmap.h @@ -89,6 +89,10 @@ static inline void perf_mmap__write_tail(struct perf_mmap *md, u64 tail) union perf_event *perf_mmap__read_forward(struct perf_mmap *map); union perf_event *perf_mmap__read_backward(struct perf_mmap *map); +union perf_event *perf_mmap__read_event(struct perf_mmap *map, + bool overwrite, + u64 *startp, u64 end); + int perf_mmap__push(struct perf_mmap *md, bool backward, void *to, int push(void *to, void *buf, size_t size)); -- 2.30.2