From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762005AbYDPUhj (ORCPT ); Wed, 16 Apr 2008 16:37:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751359AbYDPUhc (ORCPT ); Wed, 16 Apr 2008 16:37:32 -0400 Received: from sj-iport-3.cisco.com ([171.71.176.72]:39391 "EHLO sj-iport-3.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751304AbYDPUhb (ORCPT ); Wed, 16 Apr 2008 16:37:31 -0400 From: Roland Dreier To: Ingo Molnar Cc: linux-kernel@vger.kernel.org Subject: Re: [v2.6.26] what's brewing in x86.git for v2.6.26 References: <20080416202338.GA6007@elte.hu> X-Message-Flag: Warning: May contain useful information Date: Wed, 16 Apr 2008 13:37:30 -0700 In-Reply-To: <20080416202338.GA6007@elte.hu> (Ingo Molnar's message of "Wed, 16 Apr 2008 22:23:38 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-OriginalArrivalTime: 16 Apr 2008 20:37:30.0654 (UTC) FILETIME=[B116EBE0:01C8A001] Authentication-Results: sj-dkim-4; header.From=rdreier@cisco.com; dkim=pass ( sig from cisco.com/sjdkim4002 verified; ); Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > - PAT support - first step towards phasing out MTRR's for cache > attribute control I just grabbed your tree and I see that there is no pgprot_writecombine() for x86. I see that pci_mmap_page_range() handles write combining but there's no way for a PCI driver to allow userspace to mmap() part of a BAR with WC enabled. Doing this gives a big performance boost for running low-latency apps on InfiniBand hardware driven by the mlx4 driver (look for the FIXME about it in drivers/infiniband/hw/mlx4/main.c). Are there any plans to handle this somehow? Thanks, Roland