From ebeb5e4fa6f2c2d61ee1918424bd1e49d3fa7a76 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Wed, 20 May 2009 12:21:20 +0200
Subject: [PATCH] --- yaml --- r: 147478 b: refs/heads/master c:
 26b119bc811a73bac6ecf95bdf284bf31c7955f0 h: refs/heads/master v: v3

---
 [refs]                             |  2 +-
 trunk/include/linux/perf_counter.h |  8 ++++++
 trunk/kernel/perf_counter.c        | 40 +++++++++++++++++++++++++++++-
 3 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index c96fd2133916..2b0d3a1c0075 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d7b629a34fc4134a43c730b5f0197855dc4948d0
+refs/heads/master: 26b119bc811a73bac6ecf95bdf284bf31c7955f0
diff --git a/trunk/include/linux/perf_counter.h b/trunk/include/linux/perf_counter.h
index c8c1dfc22c93..f612941ef46e 100644
--- a/trunk/include/linux/perf_counter.h
+++ b/trunk/include/linux/perf_counter.h
@@ -257,6 +257,14 @@ enum perf_event_type {
 	 */
 	PERF_EVENT_COMM			= 3,
 
+	/*
+	 * struct {
+	 * 	struct perf_event_header	header;
+	 * 	u64				irq_period;
+	 * };
+	 */
+	PERF_EVENT_PERIOD		= 4,
+
 	/*
 	 * When header.misc & PERF_EVENT_MISC_OVERFLOW the event_type field
 	 * will be PERF_RECORD_*
diff --git a/trunk/kernel/perf_counter.c b/trunk/kernel/perf_counter.c
index 64113e6d1942..db02eb16c777 100644
--- a/trunk/kernel/perf_counter.c
+++ b/trunk/kernel/perf_counter.c
@@ -1046,7 +1046,9 @@ int perf_counter_task_enable(void)
 	return 0;
 }
 
-void perf_adjust_freq(struct perf_counter_context *ctx)
+static void perf_log_period(struct perf_counter *counter, u64 period);
+
+static void perf_adjust_freq(struct perf_counter_context *ctx)
 {
 	struct perf_counter *counter;
 	u64 irq_period;
@@ -1072,6 +1074,8 @@ void perf_adjust_freq(struct perf_counter_context *ctx)
 		if (!irq_period)
 			irq_period = 1;
 
+		perf_log_period(counter, irq_period);
+
 		counter->hw.irq_period = irq_period;
 		counter->hw.interrupts = 0;
 	}
@@ -2406,6 +2410,40 @@ void perf_counter_munmap(unsigned long addr, unsigned long len,
 	perf_counter_mmap_event(&mmap_event);
 }
 
+/*
+ *
+ */
+
+static void perf_log_period(struct perf_counter *counter, u64 period)
+{
+	struct perf_output_handle handle;
+	int ret;
+
+	struct {
+		struct perf_event_header	header;
+		u64				time;
+		u64				period;
+	} freq_event = {
+		.header = {
+			.type = PERF_EVENT_PERIOD,
+			.misc = 0,
+			.size = sizeof(freq_event),
+		},
+		.time = sched_clock(),
+		.period = period,
+	};
+
+	if (counter->hw.irq_period == period)
+		return;
+
+	ret = perf_output_begin(&handle, counter, sizeof(freq_event), 0, 0);
+	if (ret)
+		return;
+
+	perf_output_put(&handle, freq_event);
+	perf_output_end(&handle);
+}
+
 /*
  * Generic counter overflow handling.
  */