Messages in this thread | | | Date | Fri, 05 Dec 2008 00:49:22 -0800 (PST) | Subject | Re: [patch 0/3] [Announcement] Performance Counters for Linux | From | David Miller <> |
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From: Ingo Molnar <mingo@elte.hu> Date: Fri, 5 Dec 2008 09:42:33 +0100
> Please let me repeat: it's a _fundamental_ thesis of performance > instrumentation to not disturb the monitored context. Your insistence on > _stopping_ the monitored task breaks that fundamental axiom!
This is only a problem if you make your measurement quantums too small.
Furthermore, there are multiple registers and states to update atomically when a perf counter overflows. You're read/write thing just doesn't cut it, especially for certain kinds of hardware.
It's really a utopian view of the world. :)
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