Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1429370AbdDYKM7 (ORCPT ); Tue, 25 Apr 2017 06:12:59 -0400 Received: from foss.arm.com ([217.140.101.70]:38968 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1429353AbdDYKMx (ORCPT ); Tue, 25 Apr 2017 06:12:53 -0400 Date: Tue, 25 Apr 2017 11:13:03 +0100 From: Juri Lelli To: Paolo Bonzini Cc: KVM list , "linux-kernel@vger.kernel.org" , cgroups@vger.kernel.org, Gonglei , "Jason Wang (jasowang@redhat.com)" , "Huangweidong (C)" , linqiangmin@huawei.com, Rik van Riel , Luca Abeni , Tommaso Cucinotta , carlo.vitucci@ericsson.com Subject: Re: about CPU QoS in KVM Message-ID: <20170425101303.GA17999@e106622-lin> References: <33183CC9F5247A488A2544077AF19020DA237684@DGGEMA505-MBS.china.huawei.com> <8a5470cd-0cb2-5019-c7d3-7c407e6a6005@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8a5470cd-0cb2-5019-c7d3-7c407e6a6005@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2205 Lines: 55 Hi, just noticed this and thought I might just jump in. :) On 20/04/17 16:00, Paolo Bonzini wrote: > Adding Rik. > > Paolo > > On 20/04/2017 15:32, Gonglei (Arei) wrote: > > Hi all, > > > > Currently, KVM do the CPU resource reservation by the cgroup mechanism > > which can't do entire accurate separation because the capacity of the Linux > > scheduler. Take the public cloud as an example, some customers rent one vm > > with 8 CPUs paid by enough money, they want to get enough response > > speed on CPU scheduling. So we (the cloud platform providers ) reserve 1GHz > > CPU resources by cgroup for those VM's vcpu/pcpu. > > > > But the actual effects can't meet those requirements because the cgroup is > > limiting share usage of other processes in order to attach the reservation proportion, > > but the scheduler can't assure that. This mechanism is different with Xen, > > We can directly change the CPU weight on Xen hypervisor so that we can > > get entire accurate control on CPU resources based on accurate capacity (upper limit), > > share (weight) and reservation. > > > > So my question is do we have a good method to do CPU reservation in KVM? > > > > Thanks, > > -Gonglei Not entirely sure what your particular requirements are Gonglei, but you might be interested to know that there has been research work [1,2,3, just to name a few] that used a mainline real-time scheduling policy (SCHED_DEADLINE) to provide Qos support to virtual machines (KVM). I won't enter in too much detail, but the basic idea is to use reservation based scheduling mechanisms to enforce temporal isolation and guaranteed CPU bandwidth to VM's vcpu(s). I'm Cc-ing Tommaso, Luca and Carlo, whom can provide more information as needed. Best, - Juri [1] - http://retis.sssup.it/~nino/publication/rtlws14sdnnfs.pdf [2] - http://retis.sssup.it/~tommaso/publications/VHPC-2010.pdf [3] - http://retis.sssup.it/~tommaso/publications/RTSOAA-2009-RTV.pdf Skimming through Tommaso and Luca publications might be interesting as well. I'm pretty sure I missed the most importants papers. :) http://retis.sssup.it/~tommaso/eng/publications.html https://scholar.google.co.uk/citations?user=C3a6glEAAAAJ&hl=en