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SubjectRe: 2.5.2-pre performance degradation on an old 486

On Mon, 7 Jan 2002, Matthias Hanisch wrote:
>
> To answer your question, I wanted to profile 2.5.2-pre8 against
> 2.5.2-pre8-old-scheduler. _Fortunately_ I made some mistake and forgot to
> back out the following chunk of memory.
>
> --- v2.5.1/linux/arch/i386/kernel/process.c Thu Oct 4 18:42:54 2001
> +++ linux/arch/i386/kernel/process.c Thu Dec 27 08:21:28 2001
> @@ -125,7 +125,6 @@
> /* endless idle loop with no priority at all */
> init_idle();
> current->nice = 20;
> - current->counter = -100;
>
> while (1) {
> void (*idle)(void) = pm_idle;

Hey, that would do it. It looks like the idle task ends up being a
_normal_ process (just nice'd down), so it will get real CPU time instead
of only getting scheduled when nothing else is runnable.

Davide, I think the bounce-buffer is a red herring, it's simply that we're
wasting time in idle..

Linus

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