Re: Some questions about linux kernel.

From: David Whysong (
Date: Thu Mar 16 2000 - 17:58:10 EST

On Wed, 15 Mar 2000, Alex Belits wrote:
>On Wed, 15 Mar 2000, Horst von Brand wrote:

> Last time I have checked, scheduler handles priority of processes
>without any "time hog detector" in userspace, yet nice(1) is used all the
>time. It can argued that daemon can help to set policies for running
>processes, but the possibility to at least set policy on the program
>startup by some wrapper should improve situation a lot compared to what it
>is now.

I think that's a good approach: use something much like Rik van Riel's
patch to kill processes in an OOM situation, but allow a user-space daemon
to alter the calculation he uses to determine which process to kill. If
we're OOM the daemon can't be run, so the daemon should not try to handle
OOM situations directly.

Here is an example (poor, but it demonstrates the idea): by default, when
OOM kill the process with highest x=memory/sqrt(CPU time). But each
process might have some priority value which is added to x. This priority
may be modified by root via a userspace daemon or a tool like nice.

The daemon might not be necessary; it would be better to set priority when
the task is loaded.

The only difference between this approach and Rik's patch is that it keeps
(some) policy in userspace.


David Whysong
Astrophysics graduate student University of California, Santa Barbara
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