From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f170.google.com (mail-ie0-f170.google.com [209.85.223.170]) by kanga.kvack.org (Postfix) with ESMTP id 9D7F06B0032 for ; Sat, 25 Apr 2015 07:49:40 -0400 (EDT) Received: by iebrs15 with SMTP id rs15so100092189ieb.3 for ; Sat, 25 Apr 2015 04:49:40 -0700 (PDT) Received: from e39.co.us.ibm.com (e39.co.us.ibm.com. [32.97.110.160]) by mx.google.com with ESMTPS id j15si1580534ioe.66.2015.04.25.04.49.39 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Sat, 25 Apr 2015 04:49:39 -0700 (PDT) Received: from /spool/local by e39.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sat, 25 Apr 2015 05:49:39 -0600 Received: from b03cxnp07029.gho.boulder.ibm.com (b03cxnp07029.gho.boulder.ibm.com [9.17.130.16]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 7E4F419D803E for ; Sat, 25 Apr 2015 05:40:41 -0600 (MDT) Received: from d03av05.boulder.ibm.com (d03av05.boulder.ibm.com [9.17.195.85]) by b03cxnp07029.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t3PBnatn53936328 for ; Sat, 25 Apr 2015 04:49:36 -0700 Received: from d03av05.boulder.ibm.com (localhost [127.0.0.1]) by d03av05.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t3PBnaFA004082 for ; Sat, 25 Apr 2015 05:49:36 -0600 Date: Sat, 25 Apr 2015 04:49:35 -0700 From: "Paul E. McKenney" Subject: Re: Interacting with coherent memory on external devices Message-ID: <20150425114935.GK5561@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1429664686.27410.84.camel@kernel.crashing.org> <20150422163135.GA4062@gmail.com> <1429756456.4915.22.camel@kernel.crashing.org> <20150423185240.GO5561@linux.vnet.ibm.com> <20150424145459.GY5561@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Benjamin Herrenschmidt , Jerome Glisse , linux-kernel@vger.kernel.org, linux-mm@kvack.org, jglisse@redhat.com, mgorman@suse.de, aarcange@redhat.com, riel@redhat.com, airlied@redhat.com, aneesh.kumar@linux.vnet.ibm.com, Cameron Buschardt , Mark Hairgrove , Geoffrey Gerfin , John McKenna , akpm@linux-foundation.org On Fri, Apr 24, 2015 at 10:49:28AM -0500, Christoph Lameter wrote: > On Fri, 24 Apr 2015, Paul E. McKenney wrote: > > > can deliver, but where the cost of full-fledge hand tuning cannot be > > justified. > > > > You seem to believe that this latter category is the empty set, which > > I must confess does greatly surprise me. > > If there are already compromises are being made then why would you want to > modify the kernel for this? Some user space coding and device drivers > should be sufficient. The goal is to gain substantial performance improvement without any user-space changes. Thanx, Paul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org