From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Neukum Subject: Re: parallel suspend/resume Date: Sun, 9 Dec 2007 14:23:54 +0100 Message-ID: <200712091423.55174.oliver@neukum.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: 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: Alan Stern Cc: linux-pm@lists.linux-foundation.org List-Id: linux-pm@vger.kernel.org Am Samstag, 8. Dezember 2007 16:43:25 schrieb Alan Stern: > On Sat, 8 Dec 2007, Oliver Neukum wrote: > > > Am Freitag, 7. Dezember 2007 19:01:12 schrieb David Brownell: > > > FWIW the appended patch removes that rude "order of registration" > > > policy, so that the suspend/resume list matches the device tree. > > > It's behaved OK on PCs and, in light duty, a few development boards; > > > I've carried it around most of this year. > > > > As it is a tree, why not store it as such? > > There's no need to "store" the tree ordering specially, since all the > pointers already exist. The question is: In what order should the tree Nevertheless, we currently have a list. Why? To reverse the temporal order only? > be traversed? About the only explicit constraint we have now is that > children must be suspended before their parents, but there undoubtedly > are plenty of undocumented implicit constraints (maybe some of them > aren't known to anybody at all). We will need to know them for runtime pm. > Given the vast number of possible orders, and given that the only order > we _know_ works correctly is reverse order of registration, I don't see modus advocati diaboli: Suppose I have a system with a FibreChannel disk. Now I hot plug another FibreChannel controller and connect it to the disk. Then I disconnect the disk from the original controller. What will happen if I suspend the system? > any big reason to change. Speeding things up by parallel suspension > would be a valid reason, but it needs to be done with a great deal of > care. catch-22. Regards Oliver