Re: [PATCH 2/5] writeback: dirty position control

Peter Zijlstra
2011-08-12T13:08:49Z

On Fri, 2011-08-12 at 20:59 +0800, Wu Fengguang wrote:
> On Fri, Aug 12, 2011 at 08:54:17PM +0800, Peter Zijlstra wrote:
> > On Fri, 2011-08-12 at 00:56 +0200, Peter Zijlstra wrote:
> > >
> > > s - x 3
> > > f(x) := 1 + (-----)
> > > d
> > >
> > btw, if you want steeper slopes for rampup and brake you can add another
> > factor like:
> >
> > s - x 3
> > f(x) := 1 + a(-----)
> > d
> >
> > And solve the whole f(l)=0 thing again to determine d in l and a.
> >
> > For 0 < a < 1 the slopes increase.
>
> Yes, we can leave it as a future tuning option. For now I'm pretty
> satisfied with the current function's shape :)

Oh for sure, it just occurred to me when looking at your plots and
thought I'd at least mention it.. You know something to poke at on a
rainy afternoon ;-)