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SubjectRe: Nick's scheduler v17


Andrew Theurer wrote:

>On Friday 24 October 2003 13:10, Nick Piggin wrote:
>
>>Hi,
>>http://www.kerneltrap.org/~npiggin/v17/
>>
>>Still working on SMP and NUMA. Some (maybe) interesting things I put in are
>>- Sequential CPU balancing so you don't get a big storm of balances
>>every 1/4s.
>>- Balancing is trying to err more on the side of caution, I have to start
>> analysing it more thoroughly though.
>>
>
>+
>+ *imbalance /= 2;
>+ *imbalance = (*imbalance + FPT - 1) / FPT;
>
>I think I see what is going on here, but would something like this work out
>better?
>

Yeah, sorry its not well commented. Its still changing quite quickly.

>
> *imbalance = min(this_load - load_avg, load_avg - max_load)
>
>That way you take just enough to either have busiest_queue or this_rq's length
>be the load_avg. I suppose you could take even less, but IMO, the /=2 is
>what I really don't like. Perhaps:
>

That is _exactly_ what I had before! Thats probably the way to go. Thanks
for having a look at it.

>
>
>*imbalance = min(this_load - load_avg, load_avg - max_load);
>*imbalance = (*imbalance + FPT - 1) / FPT;
>
>This should work well for intranode balances, internode balances may need a
>little optimization, since the load_avg really does not really represent the
>load avg of the two nodes in question, just one cpu from one of them and all
>the cpus from another.
>

Yeah that does need a bit of rethinking.


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