Re: Linux 2.6.0-test6

Nick Piggin
2003-09-29T04:56:50Z

Rob Landley wrote:

>On Sunday 28 September 2003 02:03, Con Kolivas wrote:
>
>>On Sun, 28 Sep 2003 11:27, Linus Torvalds wrote:
>>
>>>from Andrew Morton. Most notably perhaps Con's scheduler changes that
>>>have been discussed extensively and made it into the -mm tree for
>>>testing.
>>>
>>For those who are trying this for the first time, please note that the
>>scheduler has been tuned to tell the difference between tasks of the _same_
>>nice level. This means do NOT renice X or it will make audio skip unless
>>you also renice your audio application by the same amount. Lots of
>>distributions have done this for the old 2.4 scheduler which could not
>>treat equal "nice" levels as differently as the new scheduler does and 2.6
>>shouldn't need special treatment.
>>
>>So for testing note the following points:
>>
>>Make sure X is NOT reniced to -10 as many distributions are doing.
>>Some shells spawn processes at nice +5 by default and this will make audio
>>apps suffer.
>>Make sure your hard disk, graphics card and audio card are performing at
>>equal standard to your 2.4 kernel (ie dma is working, graphics is fully
>>accelerated etc).
>>
>
>I.E. with your new scheduler, priority levels actually have enough of an
>effect now that things that aren't reniced can be noticeably starved by
>things that are.
>

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.