Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261926AbVD1HtK (ORCPT ); Thu, 28 Apr 2005 03:49:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262131AbVD1Hs5 (ORCPT ); Thu, 28 Apr 2005 03:48:57 -0400 Received: from gate.crashing.org ([63.228.1.57]:15842 "EHLO gate.crashing.org") by vger.kernel.org with ESMTP id S261926AbVD1Hr5 (ORCPT ); Thu, 28 Apr 2005 03:47:57 -0400 Subject: Re: pci-sysfs resource mmap broken (and PATCH) From: Benjamin Herrenschmidt To: "David S. Miller" Cc: grundler@parisc-linux.org, linux-pci@atrey.karlin.mff.cuni.cz, Linux Kernel list , Greg KH , bjorn.helgaas@hp.com, "David S. Miller" In-Reply-To: <20050428002209.12bd3f37.davem@davemloft.net> References: <1114493609.7183.55.camel@gaston> <20050426163042.GE2612@colo.lackof.org> <1114555655.7183.81.camel@gaston> <1114643616.7183.183.camel@gaston> <20050428053311.GH21784@colo.lackof.org> <20050427223702.21051afc.davem@davemloft.net> <1114670353.7182.246.camel@gaston> <20050427235056.0bd09a94.davem@davemloft.net> <1114672880.7111.254.camel@gaston> <20050428002209.12bd3f37.davem@davemloft.net> Content-Type: text/plain Date: Thu, 28 Apr 2005 17:46:38 +1000 Message-Id: <1114674398.7183.257.camel@gaston> Mime-Version: 1.0 X-Mailer: Evolution 2.0.4 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1012 Lines: 26 On Thu, 2005-04-28 at 00:22 -0700, David S. Miller wrote: > On Thu, 28 Apr 2005 17:21:19 +1000 > Benjamin Herrenschmidt wrote: > > > I have a real net big performance improvement on X by doing that > > trick ... the sysfs mmap API doesn't really provide a mean to do > > it explicitely from userland (unlike the ioctl with the old proc api) > > You can refine your test to "if PCI class is display or VGA" and the > prefetchability is set in the BAR, then elide the guard PTE > protection bit. Yes, but I was also thinking about some of those Myrinet kind of things who also provide large PCI shared memory region ... I may end up adding an explicit list of classes/vid/did that are "allowed" to use the trick to avoid problems. Ben. - 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/