Re: [PATCH] sched: fix/optimise calculation of weight-inverse

[Peter Zijlstra]

On Wed, 2011-05-11 at 18:20 +0200, Ingo Molnar wrote:
> > -            lw->inv_weight = 1 + (WMULT_CONST-lw->weight/2)
> > -                / (lw->weight+1);
> > +            lw->inv_weight = WMULT_CONST / lw->weight;
> 
> hm, i definitely think there was a rounding reason for that - but apparently 
> i'm an idiot who does not add comments to non-obvious code! :-)

I suspect I might be the idiot,

> Peter, do you remember this? 

I think what we wanted to do was minimize the error:
  err = weight - inv*WMULT_CONST

by adding another term. But we could well have simply made a mess of it
instead.

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