FC3 and the oom-killer

[Matthew Saltzman]

On Thu, 17 Feb 2005, Andy Barclay wrote:

> Hi,
>
> Matthew Saltzman wrote:
>> On Wed, 16 Feb 2005, Andy Barclay wrote:
>> 
>>> I am running 2.6.10-1.760_FC3 on my home machine.
>>> 
>>> The machine has 2 GB of RAM and 4 GB of swap.
>>> 
>>> I need to run windows XP in a vmware session (for accessing a customer's 
>>> network with a windows-only vpn).
>>> 
>>> I have allocated 1596 MB for my XP virtual machine. When I launch the 
>>> guest OS,
>>> after a short while, it gets killed.
>>> 
>>> Looking in /var/log/messages, I find that this is because of the 
>>> oom-killer. This just sucks. I don't ever want the kernel to randomly kill 
>>> my processes. After researching this, I found that
>>> if I echo "2" >/proc/sys/vm/overcommit_memory, it is supposed to disable 
>>> the oom-killer.
>>> 
>>> I've done this, and I *thought* this was working (I worked for a day 
>>> without it kicking in), but now, I'm sure the value is "2", but oom-killer 
>>> is still killing my vm. I've seen notes on the net that say the "2" is not 
>>> supported yet.
>>> 
>>> Does anyone know what I can do to stop this thing.....
>> 
>> 
>> Reduce the VM memory foootprint?
>
> I can't do that. I'm running a very memory intensive application which 
> requires at least 1.6 GB of Virtual Mememory.
>
>
>> 
>> I have a 512M machine and vmware's recommendation for maximum memory 
>> footprint is 276M.  (This is VMware-Workstation, not VMX, but I can't 
>> imagine you need much more unless you are doing some heavy-duty serving or 
>> computing.)
>
> VMware's recomended maximum is 1700+ meg for my machine.
>
> This is not a vmware problem. this is a problem with FC3. I still have 3.8GB 
> of swap free. I do NOT want the OS to ever randomly kill my applications. 
> Unless it can read my mind, it cannot know what process to kill.
>
> I just need to disable this oom-killer.

I doubt you can (but I'm not an authority on kernel internals). 
Out-of-memory conditions are machine crashers (as are out-of-disk 
conditions).  The oom-killer will choose to whack a "non-essential" 
process (from the system's point of view, not necessarily yours) in order 
to stay alive.  There are processes that must live in RAM and cannot be 
swapped out.  You may have VMware configured to insist that it is one of 
those, and the total memory they use may exceed your total available.

Things I can think of:

- If you have other processes that you are running and don't mind seeing 
killed, kill them before starting VMware.

- If you can stand the performance hit, set VMware to allow some 
swapping.

- If you don't like those solutions, get more memory.

Not sure what else to suggest.  If someone else has better information, 
they should feel free to chime in.

>
> Andy.
>
>
>

-- 
 		Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs