From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: about CPU QoS in KVM Date: Thu, 20 Apr 2017 16:00:50 +0200 Message-ID: <8a5470cd-0cb2-5019-c7d3-7c407e6a6005@redhat.com> References: <33183CC9F5247A488A2544077AF19020DA237684@DGGEMA505-MBS.china.huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Gonglei , "Jason Wang (jasowang-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org)" , "Huangweidong (C)" , linqiangmin-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, Rik van Riel To: KVM list , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Return-path: In-Reply-To: <33183CC9F5247A488A2544077AF19020DA237684-CArPBO0LKVoFkbVBhwfq5wK1hpo4iccwjNknBlVQO8k@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: kvm.vger.kernel.org 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 > >