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Commit 0f4ccd11 authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
Browse files

perf evlist: Extract perf_mmap__read() 



Extract event reader from perf_evlist__mmap_read() to perf__mmap_read().
Future commit will feed it with manually computed 'head' and 'old'
pointers.

Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1461723563-67451-2-git-send-email-wangnan0@huawei.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 0b3c2264

tools/perf/util/evlist.c

+24 −15
Original line number Diff line number Diff line
@@ -679,24 +679,15 @@ static struct perf_evsel *perf_evlist__event2evsel(struct perf_evlist *evlist, 
	return NULL;

}



union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)

static union perf_event *

perf_mmap__read(struct perf_mmap *md, bool overwrite, u64 head,

		u64 old, u64 *prev)

{

	struct perf_mmap *md = &evlist->mmap[idx];

	u64 head;

	u64 old = md->prev;

	int diff;

	unsigned char *data = md->base + page_size;

	union perf_event *event = NULL;

	int diff = head - old;



	/*

	 * Check if event was unmapped due to a POLLHUP/POLLERR.

	 */

	if (!atomic_read(&md->refcnt))

		return NULL;



	head = perf_mmap__read_head(md);

	diff = head - old;

	if (evlist->overwrite) {

	if (overwrite) {

		/*

		 * If we're further behind than half the buffer, there's a chance

		 * the writer will bite our tail and mess up the samples under us.
@@ -751,11 +742,29 @@ union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx) 
	}



broken_event:

	md->prev = old;

	if (prev)

		*prev = old;



	return event;

}



union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)

{

	struct perf_mmap *md = &evlist->mmap[idx];

	u64 head;

	u64 old = md->prev;



	/*

	 * Check if event was unmapped due to a POLLHUP/POLLERR.

	 */

	if (!atomic_read(&md->refcnt))

		return NULL;



	head = perf_mmap__read_head(md);



	return perf_mmap__read(md, evlist->overwrite, head, old, &md->prev);

}



static bool perf_mmap__empty(struct perf_mmap *md)

{

	return perf_mmap__read_head(md) == md->prev && !md->auxtrace_mmap.base;