Hi, Does it make any difference to the performance for the domU when vcpu is increased to use 2 cpu:s? /Peter _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Fri, Mar 26, 2010 at 08:45, Peter Privat <peter.privat@breilind.com> wrote:> Hi, > > Does it make any difference to the performance for the domU when vcpu is > increased to use 2 cpu:s?That rather depends on what you''re doing with that domU. -- Please keep list traffic on the list. Rob MacGregor Whoever fights monsters should see to it that in the process he doesn''t become a monster. Friedrich Nietzsche _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Fri, 2010-03-26 at 12:24 +0000, Rob MacGregor wrote:> > Hi, > > > > Does it make any difference to the performance for the domU when vcpu is > > increased to use 2 cpu:s? > > That rather depends on what you''re doing with that domU. >Sure! But I wondered if they had any real effect or were just there for satisfying software or OS:es that may require more than 1 core or whatever. Will the adding of one more virtual CPU (vcpu) have the same performance effect as like adding one more physical core to a physical hardware? (upgrading a real MB with 1 core cpu to a 2 core cpu). _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hello, Am 26.03.2010 um 13:35 Uhr schrieb Peter Privat <peter.privat@breilind.com>:> On Fri, 2010-03-26 at 12:24 +0000, Rob MacGregor wrote: > > > Does it make any difference to the performance for the domU when vcpu > > > is increased to use 2 cpu:s? > > That rather depends on what you''re doing with that domU. > Sure! But I wondered if they had any real effect or were just there for > satisfying software or OS:es that may require more than 1 core or > whatever. Will the adding of one more virtual CPU (vcpu) have the same > performance effect as like adding one more physical core to a physical > hardware? (upgrading a real MB with 1 core cpu to a 2 core cpu).it depends if you have real cpus! Say, you have 4 cores on your hardware, giving 4 vcpus to your domU will result in maximum performance for this domU on this hardware. But if you assign more than 4, performance may decrease. If you assign only 1 vcpu to your domU, this domU will only use one cpu at a time. I assume the software in your domU will scale over all available cpus. Hope this helps, -- greetings eMHa _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Fri, 2010-03-26 at 15:19 +0100, Markus Hochholdinger wrote:> Hello, > > Am 26.03.2010 um 13:35 Uhr schrieb Peter Privat <peter.privat@breilind.com>: > > On Fri, 2010-03-26 at 12:24 +0000, Rob MacGregor wrote: > > > > Does it make any difference to the performance for the domU when vcpu > > > > is increased to use 2 cpu:s? > > > That rather depends on what you''re doing with that domU. > > Sure! But I wondered if they had any real effect or were just there for > > satisfying software or OS:es that may require more than 1 core or > > whatever. Will the adding of one more virtual CPU (vcpu) have the same > > performance effect as like adding one more physical core to a physical > > hardware? (upgrading a real MB with 1 core cpu to a 2 core cpu). > > it depends if you have real cpus! Say, you have 4 cores on your hardware, > giving 4 vcpus to your domU will result in maximum performance for this domU > on this hardware. But if you assign more than 4, performance may decrease. If > you assign only 1 vcpu to your domU, this domU will only use one cpu at a > time. > > I assume the software in your domU will scale over all available cpus. > > Hope this helps, >Thank you Markus, That''s the answer I was looking for. Changing the amount of vcpus will actually have a real effect. I was just wondering if it was a cosmetic thing for the domU OS or its applications. And of course, giving more virtual cpu:s that I got physical, will then decrease performance. Great addition to the knowledge institute! :) Thanks, Peter _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users