From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f181.google.com (mail-qc0-f181.google.com [209.85.216.181]) by kanga.kvack.org (Postfix) with ESMTP id B7E626B0032 for ; Fri, 24 Apr 2015 10:14:05 -0400 (EDT) Received: by qcrf4 with SMTP id f4so26281824qcr.0 for ; Fri, 24 Apr 2015 07:14:05 -0700 (PDT) Received: from e35.co.us.ibm.com (e35.co.us.ibm.com. [32.97.110.153]) by mx.google.com with ESMTPS id k81si11522635qkh.32.2015.04.24.07.14.04 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 24 Apr 2015 07:14:04 -0700 (PDT) Received: from /spool/local by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 24 Apr 2015 08:14:03 -0600 Received: from b03cxnp08026.gho.boulder.ibm.com (b03cxnp08026.gho.boulder.ibm.com [9.17.130.18]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 81B5C19D8047 for ; Fri, 24 Apr 2015 08:05:06 -0600 (MDT) Received: from d03av05.boulder.ibm.com (d03av05.boulder.ibm.com [9.17.195.85]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t3OEDwE920906120 for ; Fri, 24 Apr 2015 07:13:59 -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 t3OEE1I8007883 for ; Fri, 24 Apr 2015 08:14:01 -0600 Date: Fri, 24 Apr 2015 07:13:59 -0700 From: "Paul E. McKenney" Subject: Re: Interacting with coherent memory on external devices Message-ID: <20150424141359.GX5561@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <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> 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: 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 On Fri, Apr 24, 2015 at 09:01:47AM -0500, Christoph Lameter wrote: > 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. In some cases, yes. But are you -really- claiming that -all- HPC workloads are highly sensitive to latency? That would be quite a claim! > > > 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. Yes, there is some portion of the market that needs both high throughput and highly predictable latencies. You are claiming that the -entire- HPC market has this sort of requirement? Again, this would be quite a claim! 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