linux-kernel - [tip:perfcounters/core] perf_counter: rework the task clock software counter

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Date:	Tue, 7 Apr 2009 09:09:13 GMT
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, paulus@...ba.org, hpa@...or.com,
	mingo@...hat.com, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
	cjashfor@...ux.vnet.ibm.com, mingo@...e.hu
Subject: [tip:perfcounters/core] perf_counter: rework the task clock software counter

Commit-ID:  a39d6f2556c4a19f58f538c6aa28bf8faca4fcb8
Gitweb:     http://git.kernel.org/tip/a39d6f2556c4a19f58f538c6aa28bf8faca4fcb8
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Mon, 6 Apr 2009 11:45:11 +0200
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Tue, 7 Apr 2009 10:49:00 +0200

perf_counter: rework the task clock software counter

Rework the task clock software counter to use the context time instead
of the task runtime clock, this removes the last such user.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
LKML-Reference: <20090406094518.445450972@...llo.nl>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 kernel/perf_counter.c |   42 ++++++++++++------------------------------
 1 files changed, 12 insertions(+), 30 deletions(-)

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 84d85ab..56b7eb5 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -974,9 +974,6 @@ int perf_counter_task_disable(void)
 	curr_rq_lock_irq_save(&flags);
 	cpu = smp_processor_id();
 
-	/* force the update of the task clock: */
-	__task_delta_exec(curr, 1);
-
 	perf_counter_task_sched_out(curr, cpu);
 
 	spin_lock(&ctx->lock);
@@ -1017,9 +1014,6 @@ int perf_counter_task_enable(void)
 	curr_rq_lock_irq_save(&flags);
 	cpu = smp_processor_id();
 
-	/* force the update of the task clock: */
-	__task_delta_exec(curr, 1);
-
 	perf_counter_task_sched_out(curr, cpu);
 
 	spin_lock(&ctx->lock);
@@ -2347,38 +2341,28 @@ static const struct hw_perf_counter_ops perf_ops_cpu_clock = {
  * Software counter: task time clock
  */
 
-/*
- * Called from within the scheduler:
- */
-static u64 task_clock_perf_counter_val(struct perf_counter *counter, int update)
-{
-	struct task_struct *curr = counter->task;
-	u64 delta;
-
-	delta = __task_delta_exec(curr, update);
-
-	return curr->se.sum_exec_runtime + delta;
-}
-
-static void task_clock_perf_counter_update(struct perf_counter *counter, u64 now)
+static void task_clock_perf_counter_update(struct perf_counter *counter)
 {
-	u64 prev;
+	u64 prev, now;
 	s64 delta;
 
-	prev = atomic64_read(&counter->hw.prev_count);
-
-	atomic64_set(&counter->hw.prev_count, now);
+	update_context_time(counter->ctx);
+	now = counter->ctx->time;
 
+	prev = atomic64_xchg(&counter->hw.prev_count, now);
 	delta = now - prev;
-
 	atomic64_add(delta, &counter->count);
 }
 
 static int task_clock_perf_counter_enable(struct perf_counter *counter)
 {
 	struct hw_perf_counter *hwc = &counter->hw;
+	u64 now;
+
+	update_context_time(counter->ctx);
+	now = counter->ctx->time;
 
-	atomic64_set(&hwc->prev_count, task_clock_perf_counter_val(counter, 0));
+	atomic64_set(&hwc->prev_count, now);
 	hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	hwc->hrtimer.function = perf_swcounter_hrtimer;
 	if (hwc->irq_period) {
@@ -2393,14 +2377,12 @@ static int task_clock_perf_counter_enable(struct perf_counter *counter)
 static void task_clock_perf_counter_disable(struct perf_counter *counter)
 {
 	hrtimer_cancel(&counter->hw.hrtimer);
-	task_clock_perf_counter_update(counter,
-			task_clock_perf_counter_val(counter, 0));
+	task_clock_perf_counter_update(counter);
 }
 
 static void task_clock_perf_counter_read(struct perf_counter *counter)
 {
-	task_clock_perf_counter_update(counter,
-			task_clock_perf_counter_val(counter, 1));
+	task_clock_perf_counter_update(counter);
 }
 
 static const struct hw_perf_counter_ops perf_ops_task_clock = {
--
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