linux-kernel - [PATCH v3] perf: honoring the architectural performance monitoring version

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Message-Id: <1434378152-4042-1-git-send-email-imrep.amz@gmail.com>
Date:	Mon, 15 Jun 2015 16:22:32 +0200
From:	Imre Palik <imrep.amz@...il.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, "Palik, Imre" <imrep@...zon.de>,
	Anthony Liguori <aliguori@...zon.com>
Subject: [PATCH v3] perf: honoring the architectural performance monitoring version

From: "Palik, Imre" <imrep@...zon.de>

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 <imrep@...zon.de>
Cc: Anthony Liguori <aliguori@...zon.com>
---
 arch/x86/kernel/cpu/perf_event_intel.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index a1e35c9..c54bb97 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -3322,13 +3322,14 @@ __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

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