Messages in this thread | | | Date | Sat, 27 Jun 2009 16:48:32 +1000 | From | Paul Mackerras <> | Subject | Re: performance counter ~0.4% error finding retired instruction count |
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Ingo Molnar writes:
> I measured 2000, but generally a few thousand cycles per invocation > sounds about right.
We could actually do a bit better than we do, fairly easily. We could attach the counters to the child after the fork instead of the parent before the fork, using a couple of pipes for synchronization. And there's probably a way to get the dynamic linker to resolve the execvp call early in the child so we avoid that overhead. I think we should be able to get the overhead down to tens of userspace instructions without doing anything unnatural.
Paul.
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