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perf record: Read from overwritable ring buffer 

Drive the evlist->bkw_mmap_state state machine during draining and when
SIGUSR2 is received. Read the backward ring buffer in record__mmap_read_all.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1468485287-33422-12-git-send-email-wangnan0@huawei.com
Signed-off-by: He Kuang <hekuang@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Wang Nan 2016-07-14 08:34:43 +00:00 committed by Arnaldo Carvalho de Melo
parent 54cc54decd
commit 057374645b
1 changed files with 30 additions and 1 deletions
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31
tools/perf/builtin-record.c
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@ -555,7 +555,7 @@ static int record__mmap_read_all(struct record *rec)
if (err)
return err;
return err;
return record__mmap_read_evlist(rec, rec->evlist, true);
}
static void record__init_features(struct record *rec)
@ -953,6 +953,17 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
for (;;) {
unsigned long long hits = rec->samples;
/*
* rec->evlist->bkw_mmap_state is possible to be
* BKW_MMAP_EMPTY here: when done == true and
* hits != rec->samples in previous round.
*
* perf_evlist__toggle_bkw_mmap ensure we never
* convert BKW_MMAP_EMPTY to BKW_MMAP_DATA_PENDING.
*/
if (trigger_is_hit(&switch_output_trigger) || done || draining)
perf_evlist__toggle_bkw_mmap(rec->evlist, BKW_MMAP_DATA_PENDING);
if (record__mmap_read_all(rec) < 0) {
trigger_error(&auxtrace_snapshot_trigger);
trigger_error(&switch_output_trigger);
@ -972,8 +983,26 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
}
if (trigger_is_hit(&switch_output_trigger)) {
/*
* If switch_output_trigger is hit, the data in
* overwritable ring buffer should have been collected,
* so bkw_mmap_state should be set to BKW_MMAP_EMPTY.
*
* If SIGUSR2 raise after or during record__mmap_read_all(),
* record__mmap_read_all() didn't collect data from
* overwritable ring buffer. Read again.
*/
if (rec->evlist->bkw_mmap_state == BKW_MMAP_RUNNING)
continue;
trigger_ready(&switch_output_trigger);
/*
* Reenable events in overwrite ring buffer after
* record__mmap_read_all(): we should have collected
* data from it.
*/
perf_evlist__toggle_bkw_mmap(rec->evlist, BKW_MMAP_RUNNING);
if (!quiet)
fprintf(stderr, "[ perf record: dump data: Woken up %ld times ]\n",
waking);