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Commit 8872481b authored by Kan Liang's avatar Kan Liang Committed by Arnaldo Carvalho de Melo
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perf mmap: Introduce perf_mmap__read_init() 



The new function perf_mmap__read_init() is factored out from
perf_mmap__push().

It is to calculate the 'start' and 'end' of the available data in
ringbuffer.

No functional change.

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/1516310792-208685-5-git-send-email-kan.liang@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent f92c8cbe

tools/perf/util/mmap.c

+27 −10
Original line number Diff line number Diff line
@@ -267,24 +267,24 @@ 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 *md, bool overwrite,

			 u64 *startp, u64 *endp)

{

	u64 head = perf_mmap__read_head(md);

	u64 old = md->prev;

	u64 end, start;

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

	unsigned long size;

	void *buf;

	int rc = 0;



	start = overwrite ? head : old;

	end = overwrite ? old : head;

	*startp = overwrite ? head : old;

	*endp = overwrite ? old : head;



	if (start == end)

	if (*startp == *endp)

		return 0;



	size = end - start;

	size = *endp - *startp;

	if (size > (unsigned long)(md->mask) + 1) {

		if (!overwrite) {

			WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n");
@@ -298,10 +298,27 @@ int perf_mmap__push(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, &start, &end))

		if (overwrite_rb_find_range(data, md->mask, head, startp, endp))

			return -1;

	}



	return 1;

}



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 = 0;



	rc = perf_mmap__read_init(md, overwrite, &start, &end);

	if (rc < 1)

		return rc;



	size = end - start;



	if ((start & md->mask) + size != (end & md->mask)) {

tools/perf/util/mmap.h

+2 −0
Original line number Diff line number Diff line
@@ -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 *md, bool overwrite,

			 u64 *startp, u64 *endp);

#endif /*__PERF_MMAP_H */