Re: Improving OOM killer

[David Rientjes <rientjes@google.com>]

On Thu, 4 Feb 2010, Rik van Riel wrote:

> > Keep in mind that we're in the oom killer here, though.  So we're out of
> > memory and we need to kill something; should Apache, Oracle, and postgres
> > not be penalized for their cost of running by factoring in something like
> > this?
> 
> No, they should not.
> 
> The goal of the OOM killer is to kill some process, so the
> system can continue running and automatically become available
> again for whatever workload the system was running.
> 
> Killing the parent process of one of the system daemons does
> not achieve that goal, because you now caused a service to no
> longer be available.
> 

The system daemon wouldn't be killed, though.  You're right that this 
heuristic would prefer the system daemon slightly more as a result of the 
forkbomb penalty, but the oom killer always attempts to sacrifice a child 
with a seperate mm before killing the selected task.  Since the forkbomb 
heuristic only adds up those children with seperate mms, we're guaranteed 
to not kill the daemon itself.

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