[PATCH 2/8] PM / Sleep: Do not check wakeup too often in try_to_freeze_tasks()

Rafael J. Wysocki
2012-02-07T01:07:58Z

From: Rafael J. Wysocki <rjw@sisk.pl>

Use the observation that it is more efficient to check the wakeup
variable once before the loop reporting tasks that were not
frozen in try_to_freeze_tasks() than to do that in every step of that
loop.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
kernel/power/process.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

Index: linux/kernel/power/process.c
===================================================================
--- linux.orig/kernel/power/process.c
+++ linux/kernel/power/process.c
@@ -98,13 +98,15 @@ static int try_to_freeze_tasks(bool user
elapsed_csecs / 100, elapsed_csecs % 100,
todo - wq_busy, wq_busy);

- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
- if (!wakeup && !freezer_should_skip(p) &&
- p != current && freezing(p) && !frozen(p))
- sched_show_task(p);
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
+ if (!wakeup) {
+ read_lock(&tasklist_lock);
+ do_each_thread(g, p) {
+ if (p != current && !freezer_should_skip(p)
+ && freezing(p) && !frozen(p))
+ sched_show_task(p);
+ } while_each_thread(g, p);
+ read_unlock(&tasklist_lock);
+ }
} else {
printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
elapsed_csecs % 100);