KSM - CPU Usage 20 - 50%

[nilski]

I was very enthousiastic about KSM. But now I noticed that ksmd is using a lot of CPU constantly.
Is this normal? I shut down all but 1 VM but to no avail.

pve-manager: 1.5-5 (pve-manager/1.5/4627)
running kernel: 2.6.32-1-pve
proxmox-ve-2.6.32: 1.5-4
pve-kernel-2.6.24-8-pve: 2.6.24-16
pve-kernel-2.6.32-1-pve: 2.6.32-4
pve-kernel-2.6.24-9-pve: 2.6.24-18
qemu-server: 1.1-11
pve-firmware: 1.0-3
libpve-storage-perl: 1.0-8
vncterm: 0.9-2
vzctl: 3.0.23-1pve8
vzdump: 1.2-5
vzprocps: 2.0.11-1dso2
vzquota: 3.0.11-1
pve-qemu-kvm: 0.11.1-2
ksm-control-daemon: 1.0-3

(Hardware is a AMD Phenom(tm) 9650 Quad-Core Processor and 8GB DDR II RAM)

edit:
Stopping ksmtuned doesn't seem to make any difference.
Found another thread with the same problems here:
https://bugzilla.redhat.com/show_bug.cgi?id=541230

 

[dietmar]

Yes, KSM need CPU - you can tune that with /etc/ksmtuned.conf.

 

[nilski]

Yes, KSM need CPU - you can tune that with /etc/ksmtuned.conf.

Hmm, that's a bit of a tradeoff.. Energyconsumption (and fan-noise!) is going up drasticly.

How should ksmtuned.conf be tuned? Does KSM need CPU all the time?

This apparently doesn't work on Debian:
"KSM is enabled by default, but limited to 2000 kernel pages. It is recommended that this be set to a more sane value with the ksm service chkconfig ksm on"
http://fedoraproject.org/wiki/Features/KSM

 

[elkondor]

where is the good tune for /etc/ksmtuned.conf ? documentation? and i don't understand if 2.6.32 is pve stable now... thanks

 

[vorgusa]

I think KSM is a bit too new to have good documentation. Fedora 12 is having the same issue. I actually moved from Proxmox to Fedora 12 for the KSM benefit but it ended up using too much CPU power for me to consider it useful. Then of course I moved back to proxmox just in time for 1.5 Hopefully in the future KSM will be more efficient

 

[elkondor]

I find this and post here: http://forum.proxmox.com/threads/3279-Correct-way-to-KSM-tunig-and-manage-2-6-32?p=18415#post18415
i reduce the cpu.

 

[Robstarusa]

I agree. I ran into this situation as well after almost 20 days of uptime. I turned off KSM.

 

[elkondor]

i config ksmtuned.conf with the paramenter in my post and work good for now....