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RE: [Xen-users] DomU load average much higher after hardware change

To: "'Paul Tomblin'" <ptomblin@xxxxxxxxx>, <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-users] DomU load average much higher after hardware change
From: "Dustin Henning" <Dustin.Henning@xxxxxxxxxxx>
Date: Wed, 30 Jun 2010 09:08:17 -0400
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Are you using the hyperthreads as VCPUs?  If so, that could be your problem, I have heard of decent results with them, but also of nightmarish ones.



From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Paul Tomblin
Sent: Wednesday, June 30, 2010 08:54
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] DomU load average much higher after hardware change



2 1GHz Pentium III

2 Gb RAM

dom0 _mem=96M
3 domUs, one with memory=1000 and vcpus=2, the others with memory=425, vcpus=1

using 2.6.26-2-xen-686 kernel and modules.



2 2.8GHz Xeons (with hyperthreading, so it looks like I've got 4 cpus in /proc/cpuinfo)

4 Gb RAM


3 domUs, one with memory=2000 and vcpus=2, the others with memory=900, vcpus=1

using 2.6.26-2-xen-amd64 kernel and modules.


You'd think that in the "After" case, everything would run much faster, but what I'm finding in the big domU is that my load average is consistently much higher - from being in the 0.2-0.3 range, I'm currently averaging 0.69 according to Munin, although it looks like it's spending a lot more time in the 1.0+ range than it ever did before.


Is there something I'm doing wrong?  Should I increase vcpus to 4 and 2 respectively?


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