[pve-devel] RFC : qemu-server : add cpu_hotplug

Alexandre DERUMIER aderumier at odiso.com
Tue Jan 7 09:36:00 CET 2014


>>I don't known if the event is the same for kvm cpu hotplug. 

This udev rule is working (I take it from opensuse and rhel)

80-hotplug-cpu-mem.rules

# Hotplug physical CPU
SUBSYSTEM=="cpu", ACTION=="add", TEST=="online", ATTR{online}=="0", \
 ATTR{online}="1"

# Hotplug physical memory
SUBSYSTEM=="memory", ACTION=="add", TEST=="state", ATTR{state}=="offline", \
 ATTR{state}="online"


Don't work with debian wheezy (3.10 kernel), but work with jessie. (So maybe it's udev version related).
Works out of the box with rhel7 guest.


----- Mail original ----- 

De: "Alexandre DERUMIER" <aderumier at odiso.com> 
À: pve-devel at pve.proxmox.com 
Envoyé: Mardi 7 Janvier 2014 07:06:48 
Objet: Re: [pve-devel] RFC : qemu-server : add cpu_hotplug 

>>(I'm not sure,but maybe this could be done auto with qemu-ga) 

I see some guy doing it with qemu-ga, but maybe it's also possible with a clean udev rule in guest. 


xen is doing it with this udev rules 

SUBSYSTEM=="cpu",ACTION=="add",RUN+="/bin/sh -c '[ ! -e /sys$devpath/online ] || echo 1 > /sys$devpath/online'" 

I don't known if the event is the same for kvm cpu hotplug. 



----- Mail original ----- 

De: "Alexandre Derumier" <aderumier at odiso.com> 
À: pve-devel at pve.proxmox.com 
Envoyé: Lundi 6 Janvier 2014 17:56:46 
Objet: [pve-devel] RFC : qemu-server : add cpu_hotplug 

Theses patches are cpu_hotplug feature. 

unplug is not yet available in current qemu. 

This introduce a new "maxcpus" config value. 

If maxcpus is defined, sockets should be set to 1, as we can only hotplug 1cpu/core step by step, up to maxcpus value. 

Tested under debian with kernel 3.2. 

cpu need to be enabled after hotplug in guest with "echo 1 > /sys/devices/system/cpu/cpuX/online". 
(I'm not sure,but maybe this could be done auto with qemu-ga) 


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