Re: SCHED_4BSD in RELENG_7 disturbs workflow

From: P.U.Kruppa <ulrich_at_pukruppa.net>
Date: Wed, 17 Oct 2007 03:16:49 +0200 (CEST)
On Tue, 16 Oct 2007, Kris Kennaway wrote:

> [LoN]Kamikaze wrote:
>> I know that RELENG_7 is not considered very near-release, but I thought I'd
>> give my 2¢ in the hope that I might have a little influence on the 
>> scheduler
>> development to my benefit.
>> 
>> The switch from RELENG_6 to RELENG_7 went relatively smooth and apart from 
>> ipw
>> causing panics. However there is one thing that's disturbing and this is 
>> the
>> scheduler. I only have single core machines, so whatever I say only applies 
>> to
>> those. If you think single-core machines are no longer important, feel free 
>> to
>> ignore this. In deed, just ignore me however much you like.
>> 
>>> From my perspective scheduling on RELENG_6 was way better. Even on a full
>> workload like a portupgrade the focused application (both in X and on the
>> console) always received enough cycles to run smoothly and applications 
>> that
>> ran in background like audio players also kept on running fine.
>> 
>> Quite the contrary on RELENG_7. During a portupgrade or even worse 'pkgdb 
>> -L'
>> (recovering lost dependencies) audio players (both graphical and mplayer)
>> scatter, either because they don't get the hard-disk or CPU-cycles (which 
>> one,
>> I don't know) and the focused application also often hangs. It just looks 
>> like
>> occasionally (under load) everything freezes for a second and then goes on
>> relatively normal.
>> 
>> I've got the impression that things compile a little faster (that might be 
>> my
>> imagination, though), but I'd rather have a smooth working experience.
>> 
>> This is just my view of the situation and I suppose it is only one of many. 
>> I
>> bid you be merciful with us single-core people, who cannot afford a slick
>> multi-core machine, because we worry how to pay for our food at the end of 
>> the
>> month.
>
> Not to say that any problems that might have developed with SCHED_4BSD should 
> not be fixed, but you should give SCHED_ULE a try since it brings benefits 
> even for single CPU systems (e.g. better interactive response).
I would like to second that. I have seen the same problems on my 
single processor system and using SCHED_ULE instead of SCHED_4BSD 
seems to improve the situation a lot.

Uli.
>
> Kris
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Peter Ulrich Kruppa
Wuppertal
Germany
Received on Tue Oct 16 2007 - 23:16:51 UTC

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