2015-06-08 12:47:11

by Imre Palik

Subject: [PATCH v2] perf: honoring the architectural performance monitoring version

From: "Palik, Imre" <[email protected]>

Architectural performance monitoring version 1 doesn't support fixed counters.
Currently, even if a hypervisor advertises support for architectural
performance monitoring version 1, perf may still tries to use the fixed
counters, as the constraints are set up based on the CPU model.

This patch ensures that perf honors the architectural performance monitoring
version returned by CPUID, and it only uses the fixed counters for version two
and above.

Some of the ideas in this patch are coming from Peter Zijlstra.

Signed-off-by: Imre Palik <[email protected]>
Cc: Anthony Liguori <[email protected]>
---
arch/x86/kernel/cpu/perf_event_intel.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index d4c0a0e..2917248 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -2604,13 +2604,13 @@ __init int intel_pmu_init(void)
* counter, so do not extend mask to generic counters
*/
for_each_event_constraint(c, x86_pmu.event_constraints) {
- if (c->cmask != FIXED_EVENT_FLAGS
- || c->idxmsk64 == INTEL_PMC_MSK_FIXED_REF_CYCLES) {
- continue;
+ if (c->cmask == FIXED_EVENT_FLAGS
+ && c->idxmsk64 != INTEL_PMC_MSK_FIXED_REF_CYCLES) {
+ c->idxmsk64 |= (1ULL << x86_pmu.num_counters) - 1;
}
-
- c->idxmsk64 |= (1ULL << x86_pmu.num_counters) - 1;
- c->weight += x86_pmu.num_counters;
+ c->idxmsk64 &=
+ ~(~0UL << (INTEL_PMC_IDX_FIXED + x86_pmu.num_counters_fixed));
+ c->weight = hweight64(c->idxmsk64);
}
}

--
1.7.9.5

2015-06-19 18:00:01

by tip-bot for Vasyl Gomonovych

Subject: [tip:perf/urgent] perf/x86: Honor the architectural performance monitoring version

Commit-ID: 2c33645d366d13b969d936b68b9f4875b1fdddea
Gitweb: http://git.kernel.org/tip/2c33645d366d13b969d936b68b9f4875b1fdddea
Author: Palik, Imre <[email protected]>
AuthorDate: Mon, 8 Jun 2015 14:46:49 +0200
Committer: Ingo Molnar <[email protected]>
CommitDate: Fri, 19 Jun 2015 09:38:48 +0200

perf/x86: Honor the architectural performance monitoring version

Architectural performance monitoring, version 1, doesn't support fixed counters.

Currently, even if a hypervisor advertises support for architectural
performance monitoring version 1, perf may still try to use the fixed
counters, as the constraints are set up based on the CPU model.

This patch ensures that perf honors the architectural performance monitoring
version returned by CPUID, and it only uses the fixed counters for version 2
and above.

(Some of the ideas in this patch came from Peter Zijlstra.)

Signed-off-by: Imre Palik <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anthony Liguori <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/kernel/cpu/perf_event_intel.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index afdd7c0..2813ea0 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -3324,13 +3324,13 @@ __init int intel_pmu_init(void)
* counter, so do not extend mask to generic counters
*/
for_each_event_constraint(c, x86_pmu.event_constraints) {
- if (c->cmask != FIXED_EVENT_FLAGS
- || c->idxmsk64 == INTEL_PMC_MSK_FIXED_REF_CYCLES) {
- continue;
+ if (c->cmask == FIXED_EVENT_FLAGS
+ && c->idxmsk64 != INTEL_PMC_MSK_FIXED_REF_CYCLES) {
+ c->idxmsk64 |= (1ULL << x86_pmu.num_counters) - 1;
}
-
- c->idxmsk64 |= (1ULL << x86_pmu.num_counters) - 1;
- c->weight += x86_pmu.num_counters;
+ c->idxmsk64 &=
+ ~(~0UL << (INTEL_PMC_IDX_FIXED + x86_pmu.num_counters_fixed));
+ c->weight = hweight64(c->idxmsk64);
}
}