Re: [Xen-users] vcpus and the virtual machine manager

[Diego Dave <diego.dave.s@xxxxxxxxx>]

Hi Mike,

The vcpus option should be together the cpus option, to assign each
vcpu to each phy cpu.

See one of my cfg files:

---------------------------------------------------------------------------------------------------------------------------------------------------------------
import os, re
arch = os.uname()[4]
if re.search('64', arch):
   arch_libdir = 'lib64'
else:
   arch_libdir = 'lib'

kernel = "/usr/lib/xen-default/boot/hvmloader"

builder='hvm'

memory = 8192

cpus = '6-7'

vcpus = 2

shadow_memory = 8

name = "correo"

pci = [ '02:00.0', '02:00.1' ]

disk = [ 'file:/home/correo.img,hda,w' ]

boot="dc"

vnc = 1
#vncunused=0
sdl = 0
vncconsole=1
vncdisplay=0
#vnclisten='0.0.0.0'
acpi = 1
apic = 1
device_model = '/usr/' + arch_libdir + '/xen-default/bin/qemu-dm'
stdvga=0
serial='pty'

usbdevice='tablet'

on_poweroff = 'destroy'
on_reboot = 'restart'
on_crash = 'restart'
---------------------------------------------------------------------------------------------------------------------------------------------------------------

Regards,

Diego



2011/8/26 Mike Sievers <saturngeist@xxxxxxxxxxxxxx>:
> Hi Diego,
>
> I wrote in my config: vcpus=4
> and I thought that the domU has the performance of 4 cpus.
>
> 1nd)
> xm vcpu-list | grep vm7
> vm7                              35     0     5   -b-     235.8 1,3,5,7
> vm7                              35     1     5   -b-     167.9 1,3,5,7
> vm7                              35     2     7   -b-      88.1 1,3,5,7
> vm7                              35     3     5   -b-      92.7 1,3,5,7
>
> 2nd)
> with cpus="4-7"
>
> xm vcpu-list | grep vm7
> vm7                              36     0     4   -b-       8.6 4-7
>
> More performance with the 2nd version?
>
> Best,
> Mike
>
> 2011/8/25 Diego Dave <diego.dave.s@xxxxxxxxx>
>>
>> Hi Mike,
>>
>> "vcpus" option set the virtual cpus, not the physical cpus to use.
>>
>> If your server have 8 cpus, they are numbered from 0 to 7.
>>
>> If you want to assign the last 4 physical cpus, you must add to the
>> DomU cfg file the option "cpus = '4-7'. Then you can see the assigning
>> using "xm vcpu-list" in command line.
>>
>> Is very good practice to manage the cpu assigning, it increases the
>> performance of VMs, and avoid problems when sharing cpus, like
>> freezing because of I/O events.
>>
>> Regards,
>>
>> Diego
>>
>> 2011/8/25 Mike Sievers <saturngeist@xxxxxxxxxxxxxx>:
>> > Hi List,
>> >
>> > with vcpus=4 I can choose the number of cpus.
>> >
>> > My virtual machine manager GUI shows:
>> > Maximum allocation: 2
>> > Host CPUs: 8
>> >
>> > How do I increase the maximum allocations?
>> >
>> > Best,
>> > Mike
>> >
>> > _______________________________________________
>> > Xen-users mailing list
>> > Xen-users@xxxxxxxxxxxxxxxxxxx
>> > http://lists.xensource.com/xen-users
>> >
>
>
> _______________________________________________
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> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users
>

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