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Date: Sun, 19 Feb 2012 12:13:18 +0100 From: Stephane Eranian <eranian@...gle.com> To: Paul Mackerras <paulus@...ba.org> Cc: Anton Blanchard <anton@...ba.org>, peterz@...radead.org, mingo@...e.hu, gleb@...hat.com, wcohen@...hat.com, vince@...ter.net, asharma@...com, andi@...stfloor.org, emunson@...bm.net, imunsie@....ibm.com, benh@...nel.crashing.org, sukadev@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org Subject: Re: [PATCH] powerpc: perf: power_pmu_start restores incorrect values, breaking frequency events Glad to see you fixed the PPC problem. On Thu, Feb 16, 2012 at 5:57 AM, Paul Mackerras <paulus@...ba.org> wrote: > On Thu, Feb 16, 2012 at 03:48:22PM +1100, Anton Blanchard wrote: >> >> perf on POWER stopped working after commit e050e3f0a71b (perf: Fix >> broken interrupt rate throttling). That patch exposed a bug in >> the POWER perf_events code. >> >> Since the PMCs count upwards and take an exception when the top bit >> is set, we want to write 0x80000000 - left in power_pmu_start. We were >> instead programming in left which effectively disables the counter >> until we eventually hit 0x80000000. This could take seconds or longer. >> >> With the patch applied I get the expected number of samples: >> >> # taskset -c 0 yes > /dev/null & >> # perf record -C 0 -a sleep 10 >> # perf report -D | grep SAMPLE | tail -1 >> SAMPLE events: 9948 >> >> Signed-off-by: Anton Blanchard <anton@...ba.org> > > Acked-by: Paul Mackerras <paulus@...ba.org> -- 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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