On 02.03.10 16:21:45, eran...@google.com wrote: > This patch adds support for randomizing the sampling period. Randomization > is very useful to mitigate the bias that exists with sampling. The random > number generator does not need to be sophisticated. This patch uses the > builtin random32() generator. > > Randomization is activated by setting perf_event_attr.random_period_width > to a non-zero value. It represents the width of the mask to apply to the > random value, i.e, maximum range of variation. The random value is applied > AROUND the period, i.e., period may be longer or shorter with a maximum > variation of half the bit width. Thus, on average the sampling period remains > equal to the initial period passed in perf_event_attr.sample_period. > > Note that randomization is not available when a target interrupt rate > (freq) is enabled. > > The last used period can be collected using the PERF_SAMPLE_PERIOD flag > in sample_type. > > Randomization is implemented in generic code thus it applies to all > PMU models and software events. > > Signed-off-by: Stephane Eranian <eran...@google.com> > > -- > include/linux/perf_event.h | 3 +++ > kernel/perf_event.c | 44 > ++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 47 insertions(+)
Reviewed-by: Robert Richter <robert.rich...@amd.com> -- Advanced Micro Devices, Inc. Operating System Research Center email: robert.rich...@amd.com ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ perfmon2-devel mailing list perfmon2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
