From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH] Remove process freezer from suspend to RAM pathway Date: Sun, 8 Jul 2007 23:07:29 +0200 Message-ID: <20070708210729.GC5401@elf.ucw.cz> References: <1183871661.3388.282.camel@localhost.localdomain> <200707082115.27363.rjw@sisk.pl> <1183928612.3388.289.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1183928612.3388.289.camel@localhost.localdomain> 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: Benjamin Herrenschmidt Cc: Matthew Garrett , linux-kernel@vger.kernel.org, Kyle Moffett , linux-pm@lists.linux-foundation.org List-Id: linux-pm@vger.kernel.org Hi! > > > I just think that the freezer approach, as it is, is backward. We can't > > > have a 3rd party try to discriminate what to freeze and what not, it > > > will always get something wrong, and in some cases with the wrong timing > > > or ordering. > > > > Nice discussion, except for one thing: the freezer doesn't decide what to > > freeze. For example, even right now kernel threads decide if they want to be > > frozen. > > Somewhat... userspace doesn't and workqueues are a gray area. But userspace must not be neccessary for kernel functioning, so that's quite okay. And we do need to solve the workqueues. > Also, I've been thinking this "icebox" idea a bit more and it seems in > fact a bit racy in some areas, at least for use by things like drivers, > unless we end up doing something aking to an RCU on suspend, waiting for > all tasks to reach userland once, but that has the same annoyances as > the current freezer. > > Thus I'm tempted to go back to saying that driver can handle things > locally :-) :-). Or perhaps freezer is not _that_ evil after all? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html