[tip:perfcounters/core] perf_counter: Fix dynamic irq_period logging

[tip-bot for Peter Zijlstra]

Commit-ID:  e220d2dcb944c5c488b6855d15ec66d76900514f
Gitweb:     http://git.kernel.org/tip/e220d2dcb944c5c488b6855d15ec66d76900514f
Author:     Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Sat, 23 May 2009 18:28:55 +0200
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Sat, 23 May 2009 19:37:44 +0200

perf_counter: Fix dynamic irq_period logging

We call perf_adjust_freq() from perf_counter_task_tick() which
is is called under the rq->lock causing lock recursion.
However, it's no longer required to be called under the
rq->lock, so remove it from under it.

Also, fix up some related comments.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: John Kacur <jkacur@xxxxxxxxxx>
LKML-Reference: <20090523163012.476197912@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 include/linux/perf_counter.h |    1 +
 kernel/perf_counter.c        |    3 ++-
 kernel/sched.c               |    3 ++-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 2eedae8..23ddd29 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -260,6 +260,7 @@ enum perf_event_type {
 	/*
 	 * struct {
 	 * 	struct perf_event_header	header;
+	 * 	u64				time;
 	 * 	u64				irq_period;
 	 * };
 	 */
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index c100554..2f410ea 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -2559,7 +2559,8 @@ void perf_counter_munmap(unsigned long addr, unsigned long len,
 }
 
 /*
- *
+ * Log irq_period changes so that analyzing tools can re-normalize the
+ * event flow.
  */
 
 static void perf_log_period(struct perf_counter *counter, u64 period)
diff --git a/kernel/sched.c b/kernel/sched.c
index 4c0d58b..ad079f0 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4875,9 +4875,10 @@ void scheduler_tick(void)
 	update_rq_clock(rq);
 	update_cpu_load(rq);
 	curr->sched_class->task_tick(rq, curr, 0);
-	perf_counter_task_tick(curr, cpu);
 	spin_unlock(&rq->lock);
 
+	perf_counter_task_tick(curr, cpu);
+
 #ifdef CONFIG_SMP
 	rq->idle_at_tick = idle_cpu(cpu);
 	trigger_load_balance(rq, cpu);
--
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