Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030758AbbDWSws (ORCPT ); Thu, 23 Apr 2015 14:52:48 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:48369 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030531AbbDWSwp (ORCPT ); Thu, 23 Apr 2015 14:52:45 -0400 Date: Thu, 23 Apr 2015 11:52:40 -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: <20150423185240.GO5561@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20150421214445.GA29093@linux.vnet.ibm.com> <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> 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: 15042318-0013-0000-0000-00000A41F790 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1270 Lines: 31 On Thu, Apr 23, 2015 at 09:38:15AM -0500, Christoph Lameter wrote: > On Thu, 23 Apr 2015, Benjamin Herrenschmidt wrote: [ . . . ] > > It might not be *your* model based on *your* application but that doesn't mean > > it's not there, and isn't relevant. > > Sadly this is the way that an entire industry does its thing. I must confess that I got lost in the pronouns. If by "this is the way" and "entire industry" you mean hand-tuning for the former and the specific industry you are in for the latter, I am with you. And again, we are not going to do anything that would prevent hand-tuning. For example, it will be possible to completely disable any migration operations that might contribute to OS jitter. And I have added a requirement that this migration mechanism not contribute to OS jitter unless it is enabled. Does that help? If by "entire industry" you mean everyone who might want to use hardware acceleration, for example, including mechanical computer-aided design, I am skeptical. 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/