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@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090523163012.476197912@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 4 insertions, 2 deletions

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index c10055416dea..2f410ea2cb39 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 4c0d58bce6b2..ad079f07c9c8 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);