linux-kernel - Re: [tip:perf/urgent] perf, x86: Catch spurious interrupts after disabling counters

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Message-ID: <20100929155102.GE9440@lenovo>
Date:	Wed, 29 Sep 2010 19:51:02 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Stephane Eranian <eranian@...gle.com>,
	Robert Richter <robert.richter@....com>
Cc:	"mingo@...hat.com" <mingo@...hat.com>,
	"hpa@...or.com" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"yinghai@...nel.org" <yinghai@...nel.org>,
	"andi@...stfloor.org" <andi@...stfloor.org>,
	"peterz@...radead.org" <peterz@...radead.org>,
	"ying.huang@...el.com" <ying.huang@...el.com>,
	"fweisbec@...il.com" <fweisbec@...il.com>,
	"ming.m.lin@...el.com" <ming.m.lin@...el.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"dzickus@...hat.com" <dzickus@...hat.com>,
	"mingo@...e.hu" <mingo@...e.hu>
Subject: Re: [tip:perf/urgent] perf, x86: Catch spurious interrupts after
	disabling counters

On Wed, Sep 29, 2010 at 07:45:28PM +0400, Cyrill Gorcunov wrote:
... 
> Btw, since x86 architectural and p4 are using same tests for
> running I presume better to have some helper rather then
> open coded pile?
> 
> Cyrill

Something like this (with some better comment in middle)?

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 6526a86..73a07fb 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1147,6 +1147,16 @@ static void x86_pmu_del(struct perf_event *event, int flags)
 	perf_event_update_userpage(event);
 }
 
+static inline int x86_pmu_spurious_irq(int idx, struct cpu_hw_events *cpuc)
+{
+	/*
+	 * Though we deactivated the counter some cpus
+	 * might still deliver spurious interrupts still
+	 * in flight. Catch them:
+	 */
+	return __test_and_clear_bit(idx, cpuc->running);
+}
+
 static int x86_pmu_handle_irq(struct pt_regs *regs)
 {
 	struct perf_sample_data data;
@@ -1162,13 +1172,7 @@ static int x86_pmu_handle_irq(struct pt_regs *regs)
 
 	for (idx = 0; idx < x86_pmu.num_counters; idx++) {
 		if (!test_bit(idx, cpuc->active_mask)) {
-			/*
-			 * Though we deactivated the counter some cpus
-			 * might still deliver spurious interrupts still
-			 * in flight. Catch them:
-			 */
-			if (__test_and_clear_bit(idx, cpuc->running))
-				handled++;
+			handled += x86_pmu_spurious_irq(idx, cpuc);
 			continue;
 		}
 
diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index c70c878..524325c 100644
--- a/arch/x86/kernel/cpu/perf_event_p4.c
+++ b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -904,8 +904,10 @@ static int p4_pmu_handle_irq(struct pt_regs *regs)
 	for (idx = 0; idx < x86_pmu.num_counters; idx++) {
 		int overflow;
 
-		if (!test_bit(idx, cpuc->active_mask))
+		if (!test_bit(idx, cpuc->active_mask)) {
+			handled += x86_pmu_spurious_irq(idx, cpuc);
 			continue;
+		}
 
 		event = cpuc->events[idx];
 		hwc = &event->hw;
--
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