Messages in this thread | | | Date | Fri, 15 Nov 2013 13:03:29 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 10/10] perf record: Add an option to force per-cpu mmaps |
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On Fri, Nov 15, 2013 at 12:56:29PM +0100, Ingo Molnar wrote: > So, here's the current status quo, there's 4 basic types of profiling > that 99% of the people are using, in order of popularity: > > perf record <cmd> > perf record -a sleep N > perf record -p <PID> > perf record -t <TID> > > The first two (which I'd guess comprise about 95% of real-world usage) > have inheritance enabled. > > The last two (-p/-t) have inheritance disabled by default.
Yes, and I would expect it to be disabled for the TID option as you explicitly select a single threads.
For the process wide thing it would make sense to enable inheritance by default though.
So the big trade-off is that for single threaded processes which do not fork you now have a single buffer, whereas with the inheritance option you'll end up with nr_cpus buffers by default.
I suppose for most normal people that's not really an issue; and I suppose all people with silly large machines already pay extra attention -- but at least make it explicit and very clear that this is so.
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