linux-kernel - [PATCH 6/6] [RFC] alarmtimer: Deboost on nanosleep

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Message-Id: <1317064434-1829-7-git-send-email-john.stultz@linaro.org>
Date:	Mon, 26 Sep 2011 12:13:54 -0700
From:	John Stultz <john.stultz@...aro.org>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	John Stultz <john.stultz@...aro.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, arve@...roid.com,
	markgross@...gnar.org, Alan Stern <stern@...land.harvard.edu>,
	amit.kucheria@...aro.org, farrowg@...ibm.com,
	"Dmitry Fink (Palm GBU)" <Dmitry.Fink@...m.com>,
	linux-pm@...ts.linux-foundation.org, khilman@...com,
	Magnus Damm <damm@...nsource.se>, mjg@...hat.com,
	peterz@...radead.org
Subject: [PATCH 6/6] [RFC] alarmtimer: Deboost on nanosleep

Example of deboosting tasks before blocking on a wakeup
source like alarmtimer based nanosleep.

With this final patch, the kernel will be able to suspend
when SCHED_STAYAWAKE flagged tasks are blocked on the alarmtimer.

CC: Rafael J. Wysocki <rjw@...k.pl>
CC: arve@...roid.com
CC: markgross@...gnar.org
CC: Alan Stern <stern@...land.harvard.edu>
CC: amit.kucheria@...aro.org
CC: farrowg@...ibm.com
CC: Dmitry Fink (Palm GBU) <Dmitry.Fink@...m.com>
CC: linux-pm@...ts.linux-foundation.org
CC: khilman@...com
CC: Magnus Damm <damm@...nsource.se>
CC: mjg@...hat.com 
CC: peterz@...radead.org 
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 kernel/time/alarmtimer.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 00ee80f..c855d40 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -568,9 +568,10 @@ static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
 	do {
 		set_current_state(TASK_INTERRUPTIBLE);
 		alarm_start(alarm, absexp, ktime_set(0, 0));
-		if (likely(alarm->data))
+		if (likely(alarm->data)) {
+			sched_deboost_task_active_count(current);
 			schedule();
-
+		}
 		alarm_cancel(alarm);
 	} while (alarm->data && !signal_pending(current));
 
-- 
1.7.3.2.146.gca209

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