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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: Wang 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: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Wang Nan 2016-04-27 02:19:20 +00:00 committed by Arnaldo Carvalho de Melo
parent 0b3c2264ae
commit 0f4ccd1181
1 changed files with 24 additions and 15 deletions
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39
tools/perf/util/evlist.c
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@ -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;