Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765023AbXE2Lb2 (ORCPT ); Tue, 29 May 2007 07:31:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757709AbXE2LbR (ORCPT ); Tue, 29 May 2007 07:31:17 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:54744 "EHLO amd.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755010AbXE2LbP (ORCPT ); Tue, 29 May 2007 07:31:15 -0400 Date: Tue, 29 May 2007 13:31:14 +0200 From: Pavel Machek To: "Rafael J. Wysocki" Cc: LKML , Andrew Morton , Gautham R Shenoy , Linus Torvalds , Nigel Cunningham , Oleg Nesterov Subject: Re: [RFC][PATCH][EXPERIMENTAL] Make kernel threads nonfreezable by default Message-ID: <20070529113114.GB23046@elf.ucw.cz> References: <200705270012.59177.rjw@sisk.pl> <20070528103302.GD18807@elf.ucw.cz> <200705282011.11526.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200705282011.11526.rjw@sisk.pl> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.11+cvs20060126 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2043 Lines: 45 Hi! > > > Index: linux-2.6.22-rc3/Documentation/power/kernel_threads.txt > > > =================================================================== > > > --- linux-2.6.22-rc3.orig/Documentation/power/kernel_threads.txt > > > +++ linux-2.6.22-rc3/Documentation/power/kernel_threads.txt > > > @@ -1,13 +1,22 @@ > > > -KERNEL THREADS > > > +The Freezer and Kernel Threads > > > > > > - > > > -Freezer > > > - > > > -Upon entering a suspended state the system will freeze all > > > -tasks. This is done by delivering pseudosignals. This affects > > > -kernel threads, too. To successfully freeze a kernel thread > > > -the thread has to check for the pseudosignal and enter the > > > -refrigerator. Code to do this looks like this: > > > +Before entering a system-wide suspend state as well as before creating a > > > +hibernation snapshot image the system will freeze all tasks, which is done > > > +by delivering fake signals. This affects kernel threads too, but they won't be > > > +frozen unless they declare that they want to. For this purpose > > > > Well... and unless thread that does disk writes or DMA _wants_ to, you > > have nice disk corruption... It should be pointed out that it is not > > voluntary for those types of threads. > > Well, that really depends. > > I think the only thing that must not be written to disk is filesystem stuff. > The other things (eg. writing directly to block devices etc.) doesn't hurt us. Well.. it can write anywhere it wants (filesystem or not) as long as the system is not going to be confused after resume by its caches not matching on-disk state. I'd prefer it not to write anywhere at all. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/