Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754486AbZJVKcT (ORCPT ); Thu, 22 Oct 2009 06:32:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753116AbZJVKcT (ORCPT ); Thu, 22 Oct 2009 06:32:19 -0400 Received: from mga09.intel.com ([134.134.136.24]:20563 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752494AbZJVKcS (ORCPT ); Thu, 22 Oct 2009 06:32:18 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.44,604,1249282800"; d="scan'208";a="460169356" Subject: Re: [RFC Patch] use MTRR for write combining if PAT is not available From: Suresh Siddha Reply-To: Suresh Siddha To: Thomas Schlichter Cc: Ingo Molnar , Jan Beulich , Jeremy Fitzhardinge , Robert Hancock , Henrique de Moraes Holschuh , "Pallipadi, Venkatesh" , Tejun Heo , "x86@kernel.org" , Yinghai Lu , Thomas Gleixner , Arjan van de Ven , "dri-devel@lists.sourceforge.net" , Ingo Molnar , "linux-kernel@vger.kernel.org" , "jbarnes@virtuousgeek.org" , Thomas Hellstrom , "H. Peter Anvin" In-Reply-To: <200910212201.36578.thomas.schlichter@web.de> References: <1394846127@web.de> <4ADF32A0020000780001B20A@vpn.id2.novell.com> <20091021173514.GA32227@elte.hu> <200910212201.36578.thomas.schlichter@web.de> Content-Type: text/plain Organization: Intel Corp Date: Thu, 22 Oct 2009 02:53:29 -0700 Message-Id: <1256205210.2530.28.camel@sbs-t61> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 (2.26.3-1.fc11) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1058 Lines: 29 On Wed, 2009-10-21 at 13:01 -0700, Thomas Schlichter wrote: > OK, so I think the attached patches should do it. Hopefully I have addressed > all your comments. Thomas, I have couple of issues with this patchset still. pci_mmap_page_range() doesn't get called for each fork(). So, we won't be ref counting the mtrr usage properly. I need to think a bit more carefully on this. Can I get back to you early next week on this, as I am traveling and need to think through this? We already keep track of some of the PAT ref counting using track_pfn_vma_copy(). And we need to extend/use something similar here. Even if we need to extend sysfs or pci vma ops, we need to increment and decrement the ref count of the mtrr register that gets used. There is no need to go through num_var_ranges etc. thanks, suresh -- 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/