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perf mmap: Introduce perf_mmap__read_init()

Browse source 
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: Kan Liang <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Jin Yao <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Wang Nan <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
This commit is contained in:
Kan Liang 2018-01-18 13:26:19 -08:00 • committed by Arnaldo Carvalho de Melo
commit 8872481bd0
2 changed files with 29 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

37
tools/perf/util/mmap.c
View file

@ -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)) {

2
tools/perf/util/mmap.h
View file

@ -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 */