From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933319Ab2GLJEq (ORCPT ); Thu, 12 Jul 2012 05:04:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25698 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933143Ab2GLJEo (ORCPT ); Thu, 12 Jul 2012 05:04:44 -0400 Message-ID: <4FFE9321.9070901@redhat.com> Date: Thu, 12 Jul 2012 12:04:33 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Tomoki Sekiyama CC: jan.kiszka@siemens.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, yrl.pp-manager.tt@hitachi.com Subject: Re: [RFC PATCH 00/18] KVM: x86: CPU isolation and direct interrupts handling by guests References: <20120628060719.19298.43879.stgit@localhost.localdomain> <4FEC8D31.3070406@redhat.com> <4FEC93BD.2070809@siemens.com> <4FEC95BC.200@redhat.com> <4FED7495.30707@hitachi.com> <4FEDC22F.9070406@redhat.com> <4FF6BEDC.8040207@hitachi.com> In-Reply-To: <4FF6BEDC.8040207@hitachi.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/06/2012 01:33 PM, Tomoki Sekiyama wrote: > Hi, > > On 2012/06/29 23:56, Avi Kivity wrote: >>> On 2012/06/29 2:34, Avi Kivity wrote: >>>> On 06/28/2012 08:26 PM, Jan Kiszka wrote: >>>>>> This is both impressive and scary. What is the target scenario here? >>>>>> Partitioning? I don't see this working for generic consolidation. >>>>> >>>>> From my POV, partitioning - including hard realtime partitions - would >>>>> provide some use cases. >>> >>> Exactly this is for partitioning that requires bare-metal performance >>> with low latency and realtime. >> >> It's hard for me to evaluate how large that segment is. Since the >> patchset is so intrusive, it needs a large potential user set to >> justify, or a large reduction in complexity, or both. > > Low latency or realtime is often required on high-end systems > like trading, automated control, HPC and so on, or for multimedias. > Those who want to run MRG as a guest, or to fully utilize high-speed > NIC are also worth using this. And not all of such applications does > not use up every CPU, so partitioning is becoming reasonable as a > number of cores in a server is increasing. > Anyway, I will try to make the patch as simple as possible. > >>> I think it is also useful for workload >>> like HPC with MPI, that is CPU intensive and that needs low latency. >> >> I keep hearing about people virtualizing these types of workloads, but I >> haven't yet understood why. > > One reason is ease of deployment of applications to nodes. > Especially in IaaS environment like Amazon EC2 Cluster Compute Instances, > virtualization is often introduced as a simple way to move applications > around flexibly among nodes shared by many users. Device assignment is not used in clouds yet, and you can't live migrate if you use device assignment. -- error compiling committee.c: too many arguments to function