Re: [PATCH 09/13] writeback: reduce per-bdi dirty threshold rampup time

From: Peter Zijlstra
Date: Wed Nov 24 2010 - 07:57:11 EST


On Wed, 2010-11-24 at 20:39 +0800, Wu Fengguang wrote:
> > > @@ -125,7 +125,7 @@ static int calc_period_shift(void)
> > > else
> > > dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) /
> > > 100;
> > > - return 2 + ilog2(dirty_total - 1);
> > > + return ilog2(dirty_total - 1) - 1;
> > > }
> > >
> > > /*
> >
> > You could actually improve upon this now that you have per-bdi bandwidth
> > estimations, simply set the period to (seconds * bandwidth) to get
> > convergence in @seconds.
>
> I'd like to, but there is the global vs. bdi discrepancy to be
> addressed first :)
>
> How about doing this simple fix first, and then revisit doing per-bdi
> vm_dirties after the bandwidth estimation goes upstream?

Sure
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