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[Xen-devel] [PATCH] Add maxvcpus support

To: "'xen-devel@xxxxxxxxxxxxxxxxxxx'" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] [PATCH] Add maxvcpus support
From: Michal Novotny <minovotn@xxxxxxxxxx>
Date: Wed, 25 Nov 2009 13:43:44 +0100
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this is patch to add maxvcpus support to xen xm command. It's using
vcpu_avail bitmask and sets the number of vcpus to maxvcpus if present.
If it's not present, old behavior is preserved.

In domain config file you can define it as follows:

maxvcpus = 4
vcpus = 2

this automatically sets vcpus to 4 and corresponding bitmask to present
2 vcpus in the guest with option to increase it up to 4 vcpus. If
maxvcpus is not present, the old behavior for vcpus is preserved, ie.
you can set vcpus to some number of vcpus to be used and the vcpu_avail
is set appropriately to use all of them. Only when you use maxvcpus and
vcpus new vcpu_avail value is calculated to show PV guest the desired
number of vcpus only.

It's been tested using RHEL-5 32-bit PV guest with maxvcpus = 4 and
vcpus = 2 and also the previous setup of vcpus = 2 only... In both cases
I was able to use 'xm vcpu-set {domainId} {numberOfVCPUs}' to increase
move vcpu count from 0 to maxvcpus/vcpus so it was working as designed.


Signed-off-By: Michal Novotny<minovotn@xxxxxxxxxx>

Attachment: xen-xm-maxvcpu-support.patch
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