Re: Linux 2.6.0-test6

From: Nick Piggin
Date: Mon Sep 29 2003 - 20:14:55 EST




bill davidsen wrote:

In article <3F77BB2C.7030402@xxxxxxxxxxxxxxx>,
Nick Piggin <piggin@xxxxxxxxxxxxxxx> wrote:

| AFAIK, Con's scheduler doesn't change the nice implementation at all.
| Possibly some of his changes amplify its problems, or, more likely they
| remove most other scheduler problems leaving this one noticable.
| | If X is running at -20, and xmms at +19, xmms is supposed to still get
| 5% of the CPU. Should be enough to run fine. Unfortunately this is
| achieved by giving X very large timeslices, so xmms's scheduling latency
| becomes large. The interactivity bonuses don't help, either.

Clearly the "some is good, more is better" approach doesn't provide
stable balance between sound and cpu hogs. It isn't a question of "how
much" cpu, just "when"which works or not.

This is sort of like the deadline scheduler in that it trades of
throughput for avoiding jackpot cases. I think that's desired behaviour
in a CPU schedular too, at least if used by humans.


I'm not sure what you mean. There is nothing good to say about Ingo's
nice mechanism though (sorry Ingo, its otherwise a very nice
scheduler!).

In my scheduler, nice -20 processes get small timeslices so scheduling
latency stays low or even gets lower, while nice +19 ones get large
timeslices for lower context switches and better cache efficiency. As
you would like.


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