Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755997AbbDXOzJ (ORCPT ); Fri, 24 Apr 2015 10:55:09 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:52860 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754588AbbDXOzG (ORCPT ); Fri, 24 Apr 2015 10:55:06 -0400 Date: Fri, 24 Apr 2015 07:54:59 -0700 From: "Paul E. McKenney" 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 Subject: Re: Interacting with coherent memory on external devices Message-ID: <20150424145459.GY5561@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1429663372.27410.75.camel@kernel.crashing.org> <20150422005757.GP5561@linux.vnet.ibm.com> <1429664686.27410.84.camel@kernel.crashing.org> <20150422163135.GA4062@gmail.com> <1429756456.4915.22.camel@kernel.crashing.org> <20150423185240.GO5561@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15042414-0033-0000-0000-000004565634 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1308 Lines: 29 On Fri, Apr 24, 2015 at 09:30:40AM -0500, Christoph Lameter wrote: > On Thu, 23 Apr 2015, Paul E. McKenney wrote: > > > If by "entire industry" you mean everyone who might want to use hardware > > acceleration, for example, including mechanical computer-aided design, > > I am skeptical. > > The industry designs GPUs with super fast special ram and accellerators > with special ram designed to do fast searches and you think you can demand page > that stuff in from the main processor? The demand paging is indeed a drawback for the option of using autonuma to handle the migration. And again, this is not intended to replace the careful hand-tuning that is required to get the last drop of performance out of the system. It is instead intended to handle the cases where the application needs substantially more performance than the CPUs alone 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. Thanx, Paul -- 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/