Adding switch-output size warning if the requested size of lower than the wakeup ring buffer size.
$ perf record --switch-output=1K ls WARNING: switch-output data size lower than wakeup kernel buffer size (258K) expect bigger perf.data sizes ... Signed-off-by: Jiri Olsa <jo...@kernel.org> Cc: David Ahern <dsah...@gmail.com> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Peter Zijlstra <a.p.zijls...@chello.nl> Cc: Wang Nan <wangn...@huawei.com> Link: http://lkml.kernel.org/n/tip-0gafw11lesghnbfoiw90k...@git.kernel.org --- tools/perf/builtin-record.c | 21 +++++++++++++++++++++ tools/perf/util/evlist.c | 2 +- tools/perf/util/evlist.h | 2 ++ 3 files changed, 24 insertions(+), 1 deletion(-) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 3fa64492ee62..4a70e964cd96 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -1377,6 +1377,23 @@ static int record__parse_mmap_pages(const struct option *opt, return ret; } +static void switch_output_size_warn(struct record *rec) +{ + u64 wakeup_size = perf_evlist__mmap_size(rec->opts.mmap_pages); + struct switch_output *s = &rec->switch_output; + + wakeup_size /= 2; + + if (s->size < wakeup_size) { + char buf[100]; + + unit_number__scnprint(buf, sizeof(buf), wakeup_size); + pr_warning("WARNING: switch-output data size lower than " + "wakeup kernel buffer size (%s) " + "expect bigger perf.data sizes\n", buf); + } +} + static int switch_output_setup(struct record *rec) { struct switch_output *s = &rec->switch_output; @@ -1410,6 +1427,10 @@ static int switch_output_setup(struct record *rec) enabled: rec->timestamp_filename = true; s->enabled = true; + + if (s->size && !rec->opts.no_buffering) + switch_output_size_warn(rec); + return 0; } diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 435ff1c94a66..9900ce5177bc 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -1184,7 +1184,7 @@ unsigned long perf_event_mlock_kb_in_pages(void) return pages; } -static size_t perf_evlist__mmap_size(unsigned long pages) +size_t perf_evlist__mmap_size(unsigned long pages) { if (pages == UINT_MAX) pages = perf_event_mlock_kb_in_pages(); diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index 4fd034f22d2f..389b9ccdf8c7 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -218,6 +218,8 @@ int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages, bool overwrite); void perf_evlist__munmap(struct perf_evlist *evlist); +size_t perf_evlist__mmap_size(unsigned long pages); + void perf_evlist__disable(struct perf_evlist *evlist); void perf_evlist__enable(struct perf_evlist *evlist); void perf_evlist__toggle_enable(struct perf_evlist *evlist); -- 2.7.4
