From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755867AbYFQHfA (ORCPT ); Tue, 17 Jun 2008 03:35:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752306AbYFQHeu (ORCPT ); Tue, 17 Jun 2008 03:34:50 -0400 Received: from mx1.redhat.com ([66.187.233.31]:49795 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752170AbYFQHet (ORCPT ); Tue, 17 Jun 2008 03:34:49 -0400 To: "Jaya Kumar" Cc: "Jeremy Fitzhardinge" , "Linux Kernel Mailing List" Subject: Re: "fb-defio: fix page list with concurrent processes" References: <4856E38E.1040203@goop.org> <45a44e480806161811k423fecf2r2d79609a5c0d057@mail.gmail.com> From: Markus Armbruster Date: Tue, 17 Jun 2008 09:34:44 +0200 In-Reply-To: <45a44e480806161811k423fecf2r2d79609a5c0d057@mail.gmail.com> (Jaya Kumar's message of "Mon\, 16 Jun 2008 18\:11\:14 -0700") Message-ID: <874p7so6p7.fsf@pike.pond.sub.org> User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Jaya Kumar" writes: > On Mon, Jun 16, 2008 at 3:05 PM, Jeremy Fitzhardinge wrote: >> Your patch "fb-defio: fix page list with concurrent processes" definitely >> seems to help with the suspend/resume problem I had with the Xen pvfb >> device. Is it queued up anywhere? It seems to be a real bugfix, and should >> probably be queued for 2.6.26... > > It isn't currently queued. I had intended to improve its performance > by taking advantage of Andrew's suggestion of using !list_empty on the > page->lru to avoid walking the page list to find the duplicate page, > but I ran into trouble since the page starts off being on the lru > list. I'll try to take a look at doing this next weekend. > > Thanks, > jaya Well, we got a bug that makes the code useless in practice for us, and a fix for it that's not quite as fast as it could be. Which is better, somewhat slow code, or somewhat useless code? I'd like to see the fix merged as soon as possible. You can always improve its performance later.