Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754915AbbDXOBz (ORCPT ); Fri, 24 Apr 2015 10:01:55 -0400 Received: from resqmta-ch2-03v.sys.comcast.net ([69.252.207.35]:57409 "EHLO resqmta-ch2-03v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754502AbbDXOBu (ORCPT ); Fri, 24 Apr 2015 10:01:50 -0400 Date: Fri, 24 Apr 2015 09:01:47 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: "Paul E. McKenney" cc: 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, benh@kernel.crashing.org, 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 In-Reply-To: <20150423192456.GQ5561@linux.vnet.ibm.com> Message-ID: References: <20150421214445.GA29093@linux.vnet.ibm.com> <20150422000538.GB6046@gmail.com> <20150422131832.GU5561@linux.vnet.ibm.com> <20150422170737.GB4062@gmail.com> <20150422185230.GD5561@linux.vnet.ibm.com> <20150423192456.GQ5561@linux.vnet.ibm.com> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1299 Lines: 31 On Thu, 23 Apr 2015, Paul E. McKenney wrote: > > As far as I know Jerome is talkeing about HPC loads and high performance > > GPU processing. This is the same use case. > > The difference is sensitivity to latency. You have latency-sensitive > HPC workloads, and Jerome is talking about HPC workloads that need > high throughput, but are insensitive to latency. Those are correlated. > > What you are proposing for High Performacne Computing is reducing the > > performance these guys trying to get. You cannot sell someone a Volkswagen > > if he needs the Ferrari. > > You do need the low-latency Ferrari. But others are best served by a > high-throughput freight train. The problem is that they want to run 2000 trains at the same time and they all must arrive at the destination before they can be send on their next trip. 1999 trains will be sitting idle because they need to wait of the one train that was delayed. This reduces the troughput. People really would like all 2000 trains to arrive on schedule so that they get more performance. -- 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/