Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754186AbZC1JGW (ORCPT ); Sat, 28 Mar 2009 05:06:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751227AbZC1JGL (ORCPT ); Sat, 28 Mar 2009 05:06:11 -0400 Received: from iona.labri.fr ([147.210.8.143]:59964 "EHLO iona.labri.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751169AbZC1JGK (ORCPT ); Sat, 28 Mar 2009 05:06:10 -0400 X-Greylist: delayed 1153 seconds by postgrey-1.27 at vger.kernel.org; Sat, 28 Mar 2009 05:06:10 EDT Message-ID: <49CDE401.2020502@inria.fr> Date: Sat, 28 Mar 2009 09:46:57 +0100 From: Brice Goglin User-Agent: Mozilla-Thunderbird 2.0.0.19 (X11/20090103) MIME-Version: 1.0 To: Peter Zijlstra CC: Eric Anholt , Andi Kleen , linux-kernel@vger.kernel.org, dri-devel@lists.sourceforge.net, Nick Piggin Subject: Re: DRM lock ordering fix series References: <1238017510-26784-1-git-send-email-eric@anholt.net> <87ocvnmhqx.fsf@basil.nowhere.org> <1238170767.8275.2397.camel@gaiman.anholt.net> <1238171805.8275.2434.camel@gaiman.anholt.net> <20090327181018.GC11935@one.firstfloor.org> <1238184629.625.44.camel@gaiman.anholt.net> <1238201922.4039.403.camel@laptop> In-Reply-To: <1238201922.4039.403.camel@laptop> X-Enigmail-Version: 0.95.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 779 Lines: 19 Peter Zijlstra wrote: > Also note that doing large gup() with gup_fast() will be undesirable due > to it disabling IRQs. So iterating say several MB worth of pages will > hurt like crazy. Currently all gup_fast() users do a single page lookup. > In 2.6.29, fs/bio.c:955, fs/direct-io.c:153 and fs/splice.c:1222 do multiple-pages lookup at once. The latter might be limited to 16 pages because of the pipe-depth, I don't know about the formers. Is there some sort of reasonable limit? A couple dozens pages at once maybe? Brice -- 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/