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Open Source and information security mailing list archives
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Date: Sun, 11 Aug 2013 22:39:00 -0300 From: Karim Yaghmour <karim.yaghmour@...rsys.com> To: Andi Kleen <andi@...stfloor.org> CC: linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>, mingo@...e.hu Subject: Re: Reading perf counters at ftrace trace boundaries On 13-08-11 10:23 PM, Andi Kleen wrote: > KVM does it, see arch/x86/kvm/pmu.c. Essentially it would be doing RDPMC. Thx for the pointer, appreciated. > But the overhead will be likely very high, some sampling approach > is likely better. Indeed. It doesn't actually have to be at every single ftrace begin/exit. But possibly starting with some kind of every nth and then drilling down as the culprit is incrementally singled-out. -- Karim Yaghmour CEO - Opersys inc. / www.opersys.com http://twitter.com/karimyaghmour -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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