Re: [PATCH 5/5] kvm: optimize GFN to memslot lookup with large slots amount

Paolo Bonzini
2014-12-02T18:45:28Z

On 02/12/2014 18:33, Radim Krčmář wrote:
>> > + while (start < end) {
>> > + slot = start + (end - start) / 2;
>> > +
>> > + if (gfn >= memslots[slot].base_gfn)
> (Even thought division is costly, I think that checking here if 'slot'
> is the one we want wouldn't help very much.)
>

Division by an unsigned is just a right shift. Division by signed
integer is a right shift + conditional move. We can change / 2 to
explicit >> 1, or change start and end to unsigned, or both.

Paolo