From: Paolo Bonzini <pbonzini@redhat.com>
To: Riccardo Brunetti <riccardo.brunetti@dnshosting.it>, kvm@vger.kernel.org
Subject: Re: CPU Overcommitting question
Date: Fri, 18 Jul 2014 17:30:37 +0200 [thread overview]
Message-ID: <53C93D9D.3010503@redhat.com> (raw)
In-Reply-To: <53C91BF3.6030507@dnshosting.it>
Il 18/07/2014 15:06, Riccardo Brunetti ha scritto:
>
>
> 1) Assign vCPUs so that vCPU(VM1) + vCPU(VM2) = total number of physical
> cores (12) (both VMs have < 12 vCPUs) (ie. 8+4)
> 2) Assign vCPUs so that vCPU(VM1) + vCPU(VM2) > total number of physical
> cores (12) (both VMs have <= 12 vCPUs) (ie. 12+8)
> 3) Assign vCPUs so that vCPU(VM1) + vCPU(VM2) > total number of physical
> cores (12) (one VM has > 12 vCPUs) (ie. 16+8)
> 4) Assign vCPUs so that vCPU(VM1) + vCPU(VM2) > total number of physical
> cores (12) (both VMs have > 12 vCPUs) (ie. 16+16)
The last two are usually bad ideas. The first two should be okay.
Overcommitting works best if the VM are I/O bound (disk or network).
If you're overcommitting, hyperthreading should in general be enabled.
Answers for very specific scenarios are hard to give though, so you
should also benchmark your deployment with realistic workloads.
Paolo
next prev parent reply other threads:[~2014-07-18 15:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-18 13:06 CPU Overcommitting question Riccardo Brunetti
2014-07-18 15:30 ` Paolo Bonzini [this message]
2014-07-18 16:49 ` riccardo.brunetti
2014-07-18 21:30 ` Paolo Bonzini
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