Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755586AbYHTVCW (ORCPT ); Wed, 20 Aug 2008 17:02:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752071AbYHTVCH (ORCPT ); Wed, 20 Aug 2008 17:02:07 -0400 Received: from wr-out-0506.google.com ([64.233.184.228]:57620 "EHLO wr-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751520AbYHTVCE (ORCPT ); Wed, 20 Aug 2008 17:02:04 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=xrkC79+ldZMZHibGvFLOWxgROG/up4CSCz3MDxmbWkPk+K11SZ9dnT8Vk4Ya63sGcI aqthctofU70Km7S944BGgRZ8GssNgADy9KqGwIpwIvOfi3SvecGTZZ6mlLSIaSzjd591 yI0q5eYOAAEBwsyc4xoFaMbkhxueOx9ZzR1bM= Message-ID: <21d7e9970808201402n4d7f5f18waba0685636bb51bf@mail.gmail.com> Date: Thu, 21 Aug 2008 07:02:00 +1000 From: "Dave Airlie" To: "Rene Herman" Subject: Re: AGP and PAT (induced?) problem (on AMD family 6) Cc: "Ingo Molnar" , "Venki Pallipadi" , "Li, Shaohua" , "Yinghai Lu" , "Andreas Herrmann" , "Arjan van de Ven" , "dri-users@lists.sourceforge.net" , "Linux Kernel" , "Siddha, Suresh B" , "Thomas Gleixner" , "H. Peter Anvin" , "Dave Jones" In-Reply-To: <48ABF6DC.8070305@keyaccess.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <48972EA8.8040001@keyaccess.nl> <20080815142218.GC12954@elte.hu> <48A59FAC.7050605@keyaccess.nl> <48AA9C3B.5030309@keyaccess.nl> <20080819102633.GE6722@elte.hu> <48AAD680.7020508@keyaccess.nl> <20080819190757.GA17470@linux-os.sc.intel.com> <20080820100440.GE28492@elte.hu> <48ABF6DC.8070305@keyaccess.nl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2065 Lines: 50 On Wed, Aug 20, 2008 at 8:50 PM, Rene Herman wrote: > On 20-08-08 12:04, Ingo Molnar wrote: > >> * Venki Pallipadi wrote: >> >>>> I'd really like a reply from the AGP or PAT side right about now. >>> >>> Hmm. Looks like there are more than 16000 entries in the PAT list! >> >> hm, btw., why is that? > > Because 64M of AGP memory divided by 4K pages is 16K. That is, the > underlying problem seems to be AGP drivers using order 0 allocations. I'm > looking. > > Do note also that this means that Venki's change would not constitite a > correct/final fix. Sure, caching the last entry speeds up traversing a 16K > entry list but the issue is that there shouldn't be a 16K entry list. > Through AGP, or maybe even by coalescing entries in the PAT list if that's > at all possible (I guess it's not really). > > Even if such a more fundamental fix isn't (easily) available, the PAT code > already comments that the list, which is sorted by ->start value, is > expected to be short, and should be turned into an rbtree if it isn't which > might be slightly less of a bandaid. > > Dave Airlie (as the MAINTAINERS entry) can't be arsed to answer email it > seems so I've added Dave Jones for a possible comment from the AGP side. > If I'm reading this right upto now, still many AGP driver (among which my > amd-k7-agp) are affected. I haven't anything to add, I'm the maintainer not the author, all the people who wrote the offending code were already involved. Dave. > > In the short run and if I'm not just mistaken, the best fix might be to make > PAT dependent on not having a dumb AGP driver (but as said, still looking). > > Note that my chipset is capable of a 2G AGP aperture. That's 512K pages if > fully used, 256K for 1G, 128K for 512M, ... > > Rene. > -- 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/