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>
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@ -555,7 +555,7 @@ static int record__mmap_read_all(struct record *rec)
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if (err)
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return err;
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return err;
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return record__mmap_read_evlist(rec, rec->evlist, true);
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}
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static void record__init_features(struct record *rec)
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@ -953,6 +953,17 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
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for (;;) {
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unsigned long long hits = rec->samples;
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/*
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* rec->evlist->bkw_mmap_state is possible to be
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* BKW_MMAP_EMPTY here: when done == true and
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* hits != rec->samples in previous round.
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*
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* perf_evlist__toggle_bkw_mmap ensure we never
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* convert BKW_MMAP_EMPTY to BKW_MMAP_DATA_PENDING.
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*/
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if (trigger_is_hit(&switch_output_trigger) || done || draining)
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perf_evlist__toggle_bkw_mmap(rec->evlist, BKW_MMAP_DATA_PENDING);
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if (record__mmap_read_all(rec) < 0) {
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trigger_error(&auxtrace_snapshot_trigger);
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trigger_error(&switch_output_trigger);
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@ -972,8 +983,26 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
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}
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if (trigger_is_hit(&switch_output_trigger)) {
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/*
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* If switch_output_trigger is hit, the data in
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* overwritable ring buffer should have been collected,
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* so bkw_mmap_state should be set to BKW_MMAP_EMPTY.
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*
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* If SIGUSR2 raise after or during record__mmap_read_all(),
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* record__mmap_read_all() didn't collect data from
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* overwritable ring buffer. Read again.
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*/
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if (rec->evlist->bkw_mmap_state == BKW_MMAP_RUNNING)
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continue;
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trigger_ready(&switch_output_trigger);
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/*
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* Reenable events in overwrite ring buffer after
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* record__mmap_read_all(): we should have collected
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* data from it.
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*/
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perf_evlist__toggle_bkw_mmap(rec->evlist, BKW_MMAP_RUNNING);
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if (!quiet)
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fprintf(stderr, "[ perf record: dump data: Woken up %ld times ]\n",
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waking);
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