Re: [Xen-users] about xm vcpu-set

[yassine ayachi <ayachi.yassine@xxxxxxxxx>]

Thanks for replays,

It's clear now,

But I already add vcpus= 4 to my config file and shutdown and start my VM (not only restart) and it works well, all of the vcpus are up and my VM performance increased.

Thanks you for explanation.

2009/5/28 Fajar A. Nugraha <fajar@xxxxxxxxx>

On Thu, May 28, 2009 at 6:52 PM, yassine ayachi

<ayachi.yassine@xxxxxxxxx> wrote:

> [root@localhost ~]# xm list
> Name                                      ID Mem(MiB) VCPUs   State
> Time(s)
> Domain-0                                 0     4035     4            r-----
>   29851.8
> domU                                       3     2047     1
> r-----   96114.6
>
> [root@localhost ~]# xm vcpu-set 3 2
>

That won't work. The maximum amount of CPU and memory for domU is
determined at domU creation. You can't simply add a CPU like that.

A workaround is to use something like this on domU config file
(old-style config):
#======================
memory = "500"
maxmem = "8000"

vcpus=8
vcpu_avail=1
#======================

that way domU will start with 500MB memory, but you'll be able to
expand it later up to 8000MB. As for CPU, it will actually start with
8 CPU but during kernel boot the other 7 will be hot-unplugged (you'll
see lots of "Breaking affinity for irq ..." message during domU boot.
It's normal). You can then hot-plug other CPUs as needed, up to a
maximum of 8.

Note that these work for xenified PV kernels only. It doesn't work
(yet) for pv_ops kernel or HVM guest.

--
Fajar

--
Yassine AYACHI
Ingénieur réseaux et systèmes

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