Messages in this thread | | | Date | Thu, 16 Feb 2012 15:57:49 +1100 | From | Paul Mackerras <> | Subject | Re: [PATCH] powerpc: perf: power_pmu_start restores incorrect values, breaking frequency events |
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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@samba.org>
Acked-by: Paul Mackerras <paulus@samba.org>
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