Re: [PATCH] VM fix for 2.4.0-test9 & OOM handler

From: Ingo Molnar (mingo@elte.hu)
Date: Mon Oct 09 2000 - 13:47:51 EST


On Mon, 9 Oct 2000, Rik van Riel wrote:

> In that case the time the process has been running and the
> CPU time used will save the process if it's been running for
> a long time.

'importance' is not something we can measure reliably within the kernel.
And assuming that a niced, not long-running process is unimportant misses
the bus as well. What if i just started an important simulation before
going to vacation for two weeks?

> would you really care if a simulation would be killed after
> 5 minutes? [...]

yes, i would. I would probably end up not using nice values. Please, Rik,
dont penalize an unrelated kernel feature!

> [...] The objective is to destroy the least amount of work, which
> means giving a bonus to processes which have used a lot of CPU time
> already ... regardless of nice value.

your OOM code does not follow this objective:

+ /*
+ * Niced processes are most likely less important, so double
+ * their badness points.
+ */
+ if (p->nice > 0)
+ points *= 2;

Niced processes *can be just as important*.

> If you have a better algorithm, feel free to send patches.

yes. Please remove the above part.

        Ingo

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