Re: Linux2.6 overcommit behaviour

Bruce Momjian wrote:

>Andrew Dunstan wrote:
>  
>
>>I believe that the swap slot can be subsequently freed, though. In 
>>theory your available virtual memory should be (almost) RAM+swap. In 
>>practice, Linux can run too close to that limit, (or way over it if you 
>>turn the checks off). But restricting the maximum possible pages to 
>>RAM/2 + swap should normally be fine. IANAKH, though.
>>
>>Also note that the truly bad thing about the OOM killer is that it can 
>>affect a process that is not making any new memory demands at all.
>>    
>>
>
>How does the OOM killer kill processes, kill -9 or kill -1 and wait?
>  
>

It sends a SIGKILL (9) unless the process is doing raw io, in which case 
it sends SIGTERM (15). It can't really wait - at this stage the kernel 
is in trouble - it can either kill processes or panic. The whole idea of 
strict accounting is not to let it get to this stage in the first place.

see mm/oom_kill.c

cheers

andrew