linux-kernel - [patch] 2.6.21-rc4 nicksched v32

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Date:	Thu, 22 Mar 2007 17:40:47 +0300
From:	Al Boldi <a1426z@...ab.com>
To:	linux-kernel@...r.kernel.org
Subject: [patch] 2.6.21-rc4 nicksched v32

Nick Piggin wrote:
> Forward port of nicksched to 2.6.21-rc4.

Great!

> Can't find my old
> design/description document for it, but it is yet another scheduler. Focus
> is on simplicity and fairness.

Simplicity is really key.

> This one tends to require X to be reniced to -10 or so for best results
> (renice -10 `pidof X`).

No problem.

> Timeslices get scaled by /proc/sys/kernel/base_timeslice. If you have bad
> interactivity you could try lowering this and see if it helps.

As I am on 2.6.20, I can't really test this patch, but I tried your sched 
from PlugSched and its not bad.

I'm getting strange numbers with chew.c, though.  Try this:
Boot into /bin/sh
Run ./chew on one console.
Run ./chew on another console.
Watch latencies.

Console 1:
pid 671, prio   0, out for  799 ms, ran for  800 ms, load  50%
pid 671, prio   0, out for  799 ms, ran for  801 ms, load  50%
pid 671, prio   0, out for  799 ms, ran for  799 ms, load  49%
pid 671, prio   0, out for  800 ms, ran for  800 ms, load  49%

Console 2:
pid 672, prio   0, out for  800 ms, ran for  799 ms, load  49%
pid 672, prio   0, out for  799 ms, ran for  800 ms, load  50%
pid 672, prio   0, out for  799 ms, ran for  800 ms, load  50%
pid 672, prio   0, out for  799 ms, ran for  799 ms, load  49%
pid 672, prio   0, out for  799 ms, ran for  799 ms, load  49%

Looks good, but now add a cpu-hog, ie. while :; do :; done

Console 1:

pid 671, prio   0, out for  799 ms, ran for  399 ms, load  33%
pid 671, prio   0, out for  799 ms, ran for  399 ms, load  33%
pid 671, prio   0, out for  799 ms, ran for  399 ms, load  33%
pid 671, prio   0, out for  799 ms, ran for  399 ms, load  33%

Console 2:
pid 672, prio   0, out for 1599 ms, ran for  799 ms, load  33%
pid 672, prio   0, out for 1599 ms, ran for  799 ms, load  33%
pid 672, prio   0, out for 1599 ms, ran for  800 ms, load  33%
pid 672, prio   0, out for 1599 ms, ran for  799 ms, load  33%

It's smooth, but latencies are double on console2.  Easy enough to fix, 
though, just press scrollock to induce a sleep and then release.

Also, latencies are huge.  Is there a way to fix latencies per nice?


Thanks!

--
Al



View attachment "chew.c" of type "text/x-csrc" (1149 bytes)