Re: configurability of OOM killer

On Mon, 2008-02-04 at 13:31 -0800, Ron Mayer wrote:
> Alvaro Herrera wrote:
> > Yeah, the only way to improve the OOM problem would be to harass the
> > Linux developers to tweak badness() so that it considers the postmaster
> > to be an essential process rather than the one to preferentially kill.
>
> Wouldn't the more general rule that Jeff Davis pointed out upstream
> make more sense?
>
> That shared memory of the children should not be added to the size
> of the parent process multiple times regardless of if something's
> an essential process or not. Since those bytes are shared, it
> seems such bytes should only be added to the badness once, no?
>
>
> (assuming I understood Jeff correctly)

Yes, that is exactly my complaint.

I am not trying to delve into the heuristics used by badness. It is not
some subtle thing that I think linux should tweak in the favor of
postgresql.

I just see something that (as I see it) is clearly wrong with the
calculation that they are using, and I want linux to fix it. It's very
easy to see, if you look at the badness algorithm, that even a well-
behaved idle postgresql daemon (or any other software of similar
architecture) will almost always be the target of the OOM killer -- even
if another process has a larger VM size (larger than postgresql
*including shared memory*, just to be clear) and is growing. And I can
demonstrate the problem with a simple test, too.

Regards,
Jeff Davis