> > Time stamps are always implicitely enabled for record currently. The > > old --time/-T option is a nop. > > > > Allow the user to disable timestamps by using --no-time > > > > This can cause some minor misaccounting (by missing mmaps), but > > significantly lowers the size of perf.data > > I'm not any big change in size: > > -rw------- 1 mingo mingo 384768 Aug 5 08:01 perf.data.timestamps > -rw------- 1 mingo mingo 336952 Aug 5 08:00 perf.data.notimestamps
It will depend on your workload. What period did you use (or did it automatically use) and what kind of workload was it? The smaller the period, the higher the benefit. There are some classes of workloads where using a smaller period is especially beneficial, essentially anything with lots of small events, instead of long loops. You also get a higher benefit if you use -c or -F, because without that each sample is smaller (no period reported) You also get higher benefit for longer traces, and traces that do not start a lot of programs, as those tend to be dominated by MMAP events and other overhead. > So either remove the --time option altogether, or fix its > 'misaccounting' so that the profile can be relied on. I don't know how to fix it. Do you? I guess one possible way to mitigate would be to lower the perf buffer sizes, then the worst case out of ordering would be less (I believe any potential problem just comes from out of order events). However that may impact performance. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/