Re: [PATCH] V-3.0 Single Priority Array O(1) CPU Scheduler Evaluation

Peter Williams
2004-08-03T04:39:47Z

Andrew Morton wrote:
> Peter Williams <pwil3058@bigpond.net.au> wrote:
>
>>>Have you considered submitting one to -mm* for wider testing?
>>
>> I've made patches available for 2.6.8-rc2-mm1 and I'll provide them for
>> mm2 as soon as possible. Is there something else I should be doing?
>
>
> I'll probably drop staircase soon, give nicksched a whizz for a couple of
> cycles. You're welcome to join the queue ;)

OK, thanks.

>
> But let me re-repeat again that CPU scheduler problems tend to take a
> _long_ time to turn up - you make some change and two months later some
> person with a weird workload on expensive hardware hits a nasty corner
> case. So I do think that we'd have to hit a nasty problem with the current
> scheduler to go making deep changes.
>
> Although most of the fragility has been in CPU/node/HT balancing rather
> than in the timeslice allocation area. I assume you're not touching the
> former.

Correct. No (algorithmic) changes have been made to load balancing type
code. There have been some modifications so that my statistics
gathering copes with a task moving to different CPU and some
modifications due to changes in data structures but these should not
change the way that load balancing etc. work.

> It's the desktop users who seem to be more affected by the
> timeslice allocation algorithms, and the testing turnaround is much faster
> there.

OK.