From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uli Luckas Subject: Why schedule in thaw_processes Date: Thu, 28 Jun 2007 15:53:48 +0200 Message-ID: <200706281553.48897.u.luckas@road.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: linux-pm@lists.linux-foundation.org List-Id: linux-pm@vger.kernel.org Dear PM Team, i am working my way through the Linux power managemen subsystem, trying to understand, benchmark and improve our ARM based device's suspend/resume cycles. I measure the time from a wakeup event until suspend_finish() returns. I was very confused, why this interval varies between 150ms and 300ms. Walking the code I found the difference between 150ms wakeups and 300ms wakeups to come from a call to schedule() in thaw_processes(). I do realise, that these extra 150ms are not wasted, as they are spent in other threads, doing what these threads need to do any way. Still an unneeded schedule() is overhead in itself and probably would not have been introduced without reason. So, can anyone explain, why this schedule() is of any benefit? regards, Uli -- ------- ROAD ...the handyPC Company - - - ) ) ) Uli Luckas Software Development ROAD GmbH Bennigsenstr. 14 | 12159 Berlin | Germany fon: +49 (30) 230069 - 64 | fax: +49 (30) 230069 - 69 url: www.road.de Amtsgericht Charlottenburg: HRB 96688 B Managing directors: Hans-Peter Constien, Hubertus von Streit