ZERO_REGION_SIZE

[Alan Cox]

On 11/15/2012 3:07 PM, Warner Losh wrote:
> On Nov 15, 2012, at 1:13 PM, Alan Cox wrote:
>> P.S. I would encourage someone with hardware to look into implementing a
>> non-iterative ffs*() using (d)clz.  The MIPS pmap would benefit from
>> this.  Basically, most pmap_enter() calls are doing an ffs*().
> ffs finds the first bit set. clz counts the number of leading zeros and thus finds the last bit set.  Would a non-iterative fls* be helpful?

The code could probably use fls* in place of ffs*.  In any case, there's 
a standard trick for using (d)clz to implement a non-iterative ffs*.

Alan