> > [email protected] [[email protected]] wrote: > | From: Kan Liang <[email protected]> > | > | Add a timer to read counter regularly. Option --counter-read-interval > | can be used to set the interval. > | Only read counter statistics at the beginning and the end is not enough. > | Sometimes, we need fine granularity to do sophisticated analysis. For > | example,10-20ms is required to do sophisticated bandwidth analysis. > | > | Signed-off-by: Kan Liang <[email protected]> > | --- > | tools/perf/Documentation/perf-record.txt | 8 +++++++ > | tools/perf/builtin-record.c | 37 > ++++++++++++++++++++++++++++++++ > | 2 files changed, 45 insertions(+) > | > | diff --git a/tools/perf/Documentation/perf-record.txt > | b/tools/perf/Documentation/perf-record.txt > | index 2e9ce77..c1d9024 100644 > | --- a/tools/perf/Documentation/perf-record.txt > | +++ b/tools/perf/Documentation/perf-record.txt > | @@ -308,6 +308,14 @@ This option sets the time out limit. The default > value is 500 ms. > | Record context switch events i.e. events of type PERF_RECORD_SWITCH > | or PERF_RECORD_SWITCH_CPU_WIDE. > | > | +--counter-read-interval:: > | +Sets the interval to do counter read regularly. This option is only > | +valid > > How about "Sets the interval at which the counter should be read"? > > | +with counter read event (:C). This option is disabled by default. It > | +means that the event counter can only be read at the beginning and the > end. > > Should this last sentence be: "When this option is disabled, the event > counter can only be read at the beginning and the end?" > > | +This option could be used when we need fine granularity to do > | +sophisticated analysis. For example, 10-20ms is required to do > | +sophisticated memory bandwidth analysis. > > I guess this is independent of the sampling frequency (perf-record -F)? > > IOW, is the need for --counter-read-interval so we can sample at one > frequency, but read the counter values/statistics at a different frequency?
Right, --counter-read-interval is independent of sampling freq. If we set --counter-read-interval to 10ms, it will read counter every 10ms no matter what sampling frequency is set. Thanks, Kan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
