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SubjectRe: [PATCH 01/17] perf tools: Always force PERF_RECORD_FINISHED_ROUND event
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Hi Jiri,

2014-06-13 (금), 00:08 +0200, Jiri Olsa:
> The PERF_RECORD_FINISHED_ROUND governs queue flushing in
> reporting, so it needs to be stored for any kind of event.
>
> Forcing the PERF_RECORD_FINISHED_ROUND event to be stored any
> time we finish the round and wrote at least one event.
>
> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
> Cc: David Ahern <dsahern@gmail.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Jean Pihet <jean.pihet@linaro.org>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> tools/perf/builtin-record.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 378b85b..4869050 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -238,6 +238,7 @@ static struct perf_event_header finished_round_event = {
>
> static int record__mmap_read_all(struct record *rec)
> {
> + u64 bytes_written = rec->bytes_written;
> int i;
> int rc = 0;
>
> @@ -250,7 +251,11 @@ static int record__mmap_read_all(struct record *rec)
> }
> }
>
> - if (perf_header__has_feat(&rec->session->header, HEADER_TRACING_DATA))
> + /*
> + * Mark the round finished in case we wrote
> + * at least one event.
> + */
> + if (bytes_written != rec->bytes_written)
> rc = record__write(rec, &finished_round_event, sizeof(finished_round_event));

Hmm.. what was the rational behind the original code? Why did it flush
the events only if session has tracepoint events? Frederic?

I guess this change alone can impact the performance in your case.
Jiri, do you have a test result of it?

Thanks,
Namhyung


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