lkml.org 
[lkml]   [2003]   [Dec]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] 2.6.0 batch scheduling, HT aware


Con Kolivas wrote:

>On Tue, 23 Dec 2003 12:36, Nick Piggin wrote:
>
>>Con Kolivas wrote:
>>
>>>I discussed this with Ingo and that's the sort of thing we thought of.
>>>Perhaps a relative crossover of 10 dynamic priorities and an absolute
>>>crossover of 5 static priorities before things got queued together. This
>>>is really only required for the UP HT case.
>>>
>>Well I guess it would still be nice for "SMP HT" as well. Hopefully the
>>code can be generic enough that it would just carry over nicely.
>>
>
>I disagree. I can't think of a real world scenario where 2+ physical cpus
>would benefit from this.
>

Well its the same problem. A nice -20 process can still lose 40-55% of its
performance to a nice 19 process, a figure of 10% is probably too high and
we'd really want it <= 5% like what happens with a single logical processor.

>
>>It does
>>have complications though because the load balancer would have to be taught
>>about it, and those architectures that do hardware priorities probably
>>don't even want it.
>>
>
>Probably the simple relative/absolute will have to suffice. However it still
>doesn't help the fact that running something cpu bound concurrently at nice 0
>with something interactive nice 0 is actually slower if you use a UP HT
>processor in SMP mode instead of UP.
>

It will be based on dynamic priorities, possibly with some feedback from
nice as well, but it probably still won't be perfect and it will probably
be very complex *cough* hardware priorities *cough* ;)

I might try to fit it into a more general priority balancing system because
we currently have similar sorts of failings on regular SMP as well.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:59    [from the cache]
©2003-2011 Jasper Spaans