From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nigel Cunningham Subject: Re: syncing the disks when entering sleep Date: Sat, 23 Jan 2010 08:31:46 +1100 Message-ID: <4B5A1942.2050003@crca.org.au> References: <76FA3B279DD9DA48896E2B404944957204E0B241@USA7061MS02.na.xerox.net> <201001222149.46839.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201001222149.46839.rjw@sisk.pl> 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: "Rafael J. Wysocki" Cc: linux-pm@lists.linux-foundation.org, "Leisner, Martin" List-Id: linux-pm@vger.kernel.org Hi. Rafael J. Wysocki wrote: > On Friday 22 January 2010, Leisner, Martin wrote: >> I noticed when we enter sleep states, it seems there's always a >> sys_sync given. >> >> When having an embedded system doing WOL (already in laptop mode to >> cache >> all the writes), it reasonable to wake up dozens of times of day and >> quickly go back to sleep. If the disk is not spun up, >> and there's some work to be done, won't the sys_sync spin up the disk >> before going to sleep? >> >> It would be good to have a knob (in /sys) you can tweak from usespace to >> >> configure the behavior of whether you want to do a sync when entering >> sleep. >> >> The ideal behavior would be: >> >> if(disk is spun up) >> then let the sync happen > > I'm not against that. Patch welcome. :-) Oooh. I am. That's providing potential for unpredictable behaviour. Much better IMO would be providing a tuning know that explicitly and unconditionally disables syncing. Regards, Nigel