[tip:perf/urgent] perf, x86: Fix Intel fixed counters base initialization

[tip-bot for Stephane Eranian]

Commit-ID:  fc66c5210ec2539e800e87d7b3a985323c7be96e
Gitweb:     http://git.kernel.org/tip/fc66c5210ec2539e800e87d7b3a985323c7be96e
Author:     Stephane Eranian <eranian@xxxxxxxxxx>
AuthorDate: Sat, 19 Mar 2011 18:20:05 +0100
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Sat, 19 Mar 2011 19:00:49 +0100

perf, x86: Fix Intel fixed counters base initialization

The following patch solves the problems introduced by Robert's
commit 41bf498 and reported by Arun Sharma. This commit gets rid
of the base + index notation for reading and writing PMU msrs.

The problem is that for fixed counters, the new calculation for
the base did not take into account the fixed counter indexes,
thus all fixed counters were read/written from fixed counter 0.
Although all fixed counters share the same config MSR, they each
have their own counter register.

Without:

 $ task -e unhalted_core_cycles -e instructions_retired -e baclears noploop 1 noploop for 1 seconds

  242202299 unhalted_core_cycles (0.00% scaling, ena=1000790892, run=1000790892)
 2389685946 instructions_retired (0.00% scaling, ena=1000790892, run=1000790892)
      49473 baclears             (0.00% scaling, ena=1000790892, run=1000790892)

With:

 $ task -e unhalted_core_cycles -e instructions_retired -e baclears noploop 1 noploop for 1 seconds

 2392703238 unhalted_core_cycles (0.00% scaling, ena=1000840809, run=1000840809)
 2389793744 instructions_retired (0.00% scaling, ena=1000840809, run=1000840809)
      47863 baclears             (0.00% scaling, ena=1000840809, run=1000840809)

Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: peterz@xxxxxxxxxxxxx
Cc: ming.m.lin@xxxxxxxxx
Cc: robert.richter@xxxxxxx
Cc: asharma@xxxxxx
Cc: perfmon2-devel@xxxxxxxxxxxx
LKML-Reference: <20110319172005.GB4978@quad>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 arch/x86/kernel/cpu/perf_event.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index e8dbe17..ec46eea 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -912,7 +912,7 @@ static inline void x86_assign_hw_event(struct perf_event *event,
 		hwc->event_base	= 0;
 	} else if (hwc->idx >= X86_PMC_IDX_FIXED) {
 		hwc->config_base = MSR_ARCH_PERFMON_FIXED_CTR_CTRL;
-		hwc->event_base = MSR_ARCH_PERFMON_FIXED_CTR0;
+		hwc->event_base = MSR_ARCH_PERFMON_FIXED_CTR0 + (hwc->idx - X86_PMC_IDX_FIXED);
 	} else {
 		hwc->config_base = x86_pmu_config_addr(hwc->idx);
 		hwc->event_base  = x86_pmu_event_addr(hwc->idx);
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/