Xen users - Mar 2010 - vcpus and vcpu_avail

Hi,
i want to start domain with 2 cpus avail, but also have the opportunity
to change on-the-fly the number of cpus to, for example, 4.

in my domain.cfg i have:

vcpus       = 2
vcpu_avail =  7

The domain starts with 2 cpus, as expected, but rising the number
does not work. It silently fails. Lowering the number works as expected.

$ xm vcpu-set domain 3

$ xm list
Name                                        ID   Mem VCPUs      State   
Time(s)
Domain-0                                     0  7016     8     r-----   
1445.7
domain                                      53   256     2     -b----    
 45.8

Did I miss something? Any suggestions?

Dom0 system is Debian/lenny based.
xm info:
host                   : dom0
release                : 2.6.26-2-xen-amd64
version                : #1 SMP Wed Jan 13 00:12:41 UTC 2010
machine                : x86_64
nr_cpus                : 8
nr_nodes               : 1
cores_per_socket       : 4
threads_per_core       : 1
cpu_mhz                : 1995
total_memory           : 8185
free_memory            : 515
node_to_cpu            : node0:0-7
xen_major              : 3
xen_minor              : 2
xen_extra              : -1
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 
hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler          : credit
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          : unavailable
cc_compiler            : gcc version 4.3.1 (Debian 4.3.1-2)
cc_compile_by          : waldi
cc_compile_domain      : debian.org
cc_compile_date        : Sat Jun 28 09:32:18 UTC 2008
xend_config_format     : 4

Regadrs,
   Pawel



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2010/3/5 Pawel J. <sq6elt@wp.pl>:
> in my domain.cfg i have:
>
> vcpus       = 2
> vcpu_avail =  7
you have it backwards. It should be

vcpus       = 7
vcpu_avail =  2

IIRC it only works for PV domUs, and only if your xen version knows
how to handle vcpu_avail directive. Run "xm create --help_config |
grep cpu" to make sure.

-- 
Fajar

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