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Date: Mon, 14 May 2012 09:05:07 +0200 From: Ingo Molnar <mingo@...nel.org> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@...radead.org>, linux-kernel@...r.kernel.org, Arjan van de Ven <arjan@...radead.org>, David Ahern <dsahern@...il.com>, Frederic Weisbecker <fweisbec@...il.com>, Mike Galbraith <efault@....de>, Namhyung Kim <namhyung@...il.com>, Paul Mackerras <paulus@...ba.org>, Peter Zijlstra <peterz@...radead.org>, Stephane Eranian <eranian@...gle.com> Subject: Re: [GIT PULL 0/8] Annotation weekly ponies delivery * Linus Torvalds <torvalds@...ux-foundation.org> wrote: > On Sat, May 12, 2012 at 2:25 PM, Arnaldo Carvalho de Melo > <acme@...radead.org> wrote: > > > > Didn't notice it, but then I'm not updating the kernel that frequently, > > will check on this Sandy Bridge nobo (i7-2920XM). > > I think SNB has problems with PEBS and cycles anyway. I have a > westmere machine that I use for profiling for that reason. I have a pre-westmere Nehalem that I use most for perf testing - that one appears to be working well both with default cycles and with cycles:pp. Will test on a Westmere. btw., Arnaldo, could we make cycles:pp the default event on perf record and perf top? We have the new AMD IBS code in perf/core queued up for v3.5, which is roughly equivalent to cycles:p on Intel CPUs, so if we standardize on cycles:pp we'll get improved skidless (and on Intel pre-SB CPUs, precise) profiling output by default. While at it I'd also suggest increasing the default sampling frequency, from 1000 Hz per CPU to at least 4Khz auto-freq or so - this should work well all across the board I think. CPUs are getting faster and command/app run times are getting shorter, 1Khz is a bit low IMO. Thanks, Ingo -- 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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