Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762145AbZC0VEf (ORCPT ); Fri, 27 Mar 2009 17:04:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759905AbZC0VEX (ORCPT ); Fri, 27 Mar 2009 17:04:23 -0400 Received: from one.firstfloor.org ([213.235.205.2]:46596 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761409AbZC0VEW (ORCPT ); Fri, 27 Mar 2009 17:04:22 -0400 Date: Fri, 27 Mar 2009 22:05:34 +0100 From: Andi Kleen To: Eric Anholt Cc: Andi Kleen , linux-kernel@vger.kernel.org, dri-devel@lists.sourceforge.net Subject: Re: DRM lock ordering fix series Message-ID: <20090327210534.GD11935@one.firstfloor.org> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1238184629.625.44.camel@gaiman.anholt.net> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 888 Lines: 19 > OK. I'm not too excited here -- 10% of 2% of the CPU time doesn't get > me to the 10% loss that the slow path added up to. Most of the cost is > in k{un,}map_atomic of the returned pages. If the gup somehow filled in > the user's PTEs, I'd be happy and always use that (since then I'd have On x86 the user PTEs are already there if it's your current process context so you could just use them. And it's even safe to use as long as its locked. But that would be a x86 specific hack, not working on all platforms that have split kernel user address spaces (that includes UML) -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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/