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Commit 7bb45972 authored by Kan Liang's avatar Kan Liang Committed by Arnaldo Carvalho de Melo
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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: default avatarKan Liang <kan.liang@intel.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-9-git-send-email-kan.liang@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent ee023de0

tools/perf/util/mmap.c

+39 −0
Original line number Diff line number Diff line
@@ -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;

tools/perf/util/mmap.h

+4 −0
Original line number Diff line number Diff line
@@ -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));