[tip:perf/urgent] powerpc, perf: Fix frequency calculation for overflowing counters (FSL version)

[tip-bot for Anton Blanchard]

Commit-ID:  8c8a9b25b5de3f1eeac721cf34f4379e56d5d694
Gitweb:     http://git.kernel.org/tip/8c8a9b25b5de3f1eeac721cf34f4379e56d5d694
Author:     Anton Blanchard <anton@xxxxxxxxx>
AuthorDate: Tue, 18 Jan 2011 21:44:04 +1100
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 19 Jan 2011 20:05:42 +0100

powerpc, perf: Fix frequency calculation for overflowing counters (FSL version)

When fixing the frequency calculations for perf on powerpc I
forgot to fix the FSL version.

If we dont set event->hw.last_period the frequency to period
calculations in perf go haywire and we continually
throttle/unthrottle the PMU.

Signed-off-by: Anton Blanchard <anton@xxxxxxxxx>
Acked-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Scott Wood <scottwood@xxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx>
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
LKML-Reference: <20110118214404.2f42e634@kryten>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 arch/powerpc/kernel/perf_event_fsl_emb.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/perf_event_fsl_emb.c b/arch/powerpc/kernel/perf_event_fsl_emb.c
index 4dcf5f8..b0dc8f7 100644
--- a/arch/powerpc/kernel/perf_event_fsl_emb.c
+++ b/arch/powerpc/kernel/perf_event_fsl_emb.c
@@ -596,6 +596,7 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
 			if (left <= 0)
 				left = period;
 			record = 1;
+			event->hw.last_period = event->hw.sample_period;
 		}
 		if (left < 0x80000000LL)
 			val = 0x80000000LL - left;
--
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