linux-kernel - [PATCH 3/3] perf,x86: use common PMU interrupt disabled code

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Date:	Fri, 16 May 2014 17:18:07 -0400 (EDT)
From:	Vince Weaver <vincent.weaver@...ne.edu>
To:	Vince Weaver <vincent.weaver@...ne.edu>
cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Will Deacon <will.deacon@....com>,
	Peter Zijlstra <peterz@...radead.org>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>
Subject: [PATCH 3/3] perf,x86: use common PMU interrupt disabled code


Make the x86 perf code use the new common PMU interrupt disabled code.

Typically most x86 machines have working PMU interrupts, although
some older p6-class machines had this problem.

Signed-off-by: Vince Weaver <vincent.weaver@...ne.edu>

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index ae407f7..adba966 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -303,15 +303,6 @@ int x86_setup_perfctr(struct perf_event *event)
 		hwc->sample_period = x86_pmu.max_period;
 		hwc->last_period = hwc->sample_period;
 		local64_set(&hwc->period_left, hwc->sample_period);
-	} else {
-		/*
-		 * If we have a PMU initialized but no APIC
-		 * interrupts, we cannot sample hardware
-		 * events (user-space has to fall back and
-		 * sample via a hrtimer based software event):
-		 */
-		if (!x86_pmu.apic)
-			return -EOPNOTSUPP;
 	}
 
 	if (attr->type == PERF_TYPE_RAW)
@@ -1365,6 +1356,15 @@ static void __init pmu_check_apic(void)
 	x86_pmu.apic = 0;
 	pr_info("no APIC, boot with the \"lapic\" boot parameter to force-enable it.\n");
 	pr_info("no hardware sampling interrupt available.\n");
+
+	/*
+	 * If we have a PMU initialized but no APIC
+	 * interrupts, we cannot sample hardware
+	 * events (user-space has to fall back and
+	 * sample via a hrtimer based software event):
+	 */
+	pmu.capabilities |= PERF_PMU_NO_INTERRUPT;
+
 }
 
 static struct attribute_group x86_pmu_format_group = {
--
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