https://github.com/torvalds/linux
Revision 9a45a9407c69d068500923480884661e2b9cc421 authored by Anton Blanchard on 15 February 2012, 18:48:22 UTC, committed by Benjamin Herrenschmidt on 16 February 2012, 05:24:35 UTC
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:

          SAMPLE events:       9948

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: <stable@kernel.org>
1 parent 64f8c13
History
Tip revision: 9a45a9407c69d068500923480884661e2b9cc421 authored by Anton Blanchard on 15 February 2012, 18:48:22 UTC
powerpc/perf: power_pmu_start restores incorrect values, breaking frequency events
Tip revision: 9a45a94
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