[dm-devel] Re: IO scheduler based IO controller V10

[Vivek Goyal <vgoyal redhat com>]

On Wed, Sep 30, 2009 at 10:05:39PM +0200, Mike Galbraith wrote:
> 
>  
> >  		/*
> > +		 * We may have seeky queues, don't throttle up just yet.
> > +		 */
> > +		if (time_before(jiffies, cfqd->last_seeker + CIC_SEEK_THR))
> > +			return 0;
> > +
> 
> bzzzt.  Window too large, but the though is to let them overload, but
> not instantly.
> 

CIC_SEEK_THR is 8K jiffies so that would be 8seconds on 1000HZ system. Try
using one "slice_idle" period of 8 ms. But it might turn out to be too
short depending on the disk speed.

Thanks
Vivek