Re: Nick's scheduler v17

[Nick Piggin <piggin@cyberone.com.au>]

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.