From 057374645bd42e8bcf22aa4529f99cf7c920a1c6 Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Thu, 14 Jul 2016 08:34:43 +0000 Subject: [PATCH] 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 Acked-by: Jiri Olsa Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Nilay Vaish Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1468485287-33422-12-git-send-email-wangnan0@huawei.com Signed-off-by: He Kuang Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-record.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index d4f15e76c98a..b87070b1f492 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -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); -- 2.20.1