Re: KVM and the OOM-Killer

[Athanasius <kvm@miggy.org>]

[-- Attachment #1: Type: text/plain, Size: 1281 bytes --]

On Thu, May 13, 2010 at 01:20:31PM +0100, James Stevens wrote:
> We have a KVM host with 48Gb of RAM and run about 20 KVM clients on it.  
> After some time - different time depending on the kernel version - the  
> VM host kernel will start OOM-Killing the VM clients, even when there is  
> lots of free RAM (>10Gb) and free SWAP (>34Gb).

  It seems going to a 64 bit kernel is what you want, but I thought it
worth mentioning the available method to say "try not to OOM-kill *this*
process":

	echo "-16" > /proc/<pid>/oom_adj

I go through some convolutions in starting KVM VMs so that this gets
done automatically for them.  It basically scores the process *way* down
for consideration to be OOM-killed.  Handy if you might accidentally run
something on the KVM host that chews up all the available memory.  It
should then get killed instead of the VMs.  You can also use '-17' to
exclude the process from consideration entirely.
  See <kernel source>/Documentation/filesystems/proc.txt for details.

-- 
- Athanasius = Athanasius(at)miggy.org / http://www.miggy.org/
                  Finger athan(at)fysh.org for PGP key
	   "And it's me who is my enemy. Me who beats me up.
Me who makes the monsters. Me who strips my confidence." Paula Cole - ME

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 197 bytes --]