[Beowulf] Re: Memory limit enforcement

[Andrew Shewmaker]

On 10/10/07, David Mathog <mathog at caltech.edu> wrote:
> David Kewley <kewley at gps.caltech.edu> wrote:
>
>
> > But the kernel doesn't really enforce anything useful.
>
> I agree, the kernel should be able to enforce these sorts of limits
> on all processes of a user at once.
>
> Write Linus or whichever kernel developer you think is most likely to
> know now to implement this and request it as a new feature, and explain
> the situation.

The kernel developer Matt Mackall has been working on making the
question of how much memory an app is using more easily answered.

http://lwn.net/Articles/230975/

According to the Linux Weather Forecast, we might see these patches
included in 2.6.25

http://www.linux-foundation.org/en/Linux_Weather_Forecast

Like Kilian, I've used the sysctl overcommit_memory and overcommit_ratio
settings.  Partly because for some RHEL4 on diskless nodes (4 socket
opterons with 32GB RAM), the OOM killer didn't actually work and the
watchdog would panic the kernel.  I also saw bad behavior under RHEL4
for diskful systems with 8GB RAM and plenty of swap.  Swapping
seemed to hang machines when it should have only slowed down the
system and then recovered.

-- 
Andrew Shewmaker