[PATCH 0/3] lib/int_sqrt: Fix, optimize and document

[Peter Zijlstra]

Hi,

Here are a few patches that should improve things lib/int_sqrt. As stated
elsewhere; I'm looking at using int_sqrt() to calculate the stdev on a normal
distribution and am expecting the input values to be smallish.

In any case, these optimizations should work fine for large numbers too. And
if you have a find-last-set or count-leading-zeros instruction they rock ;-)

I can post the tool used to generate the numbers or do a patch to add it to
tools/testing/ if people care. The cold numbers are fairly sensitive to code
layout (GCC version, random changes etc..), so I expect the branch predictor of
my SKL is only partially confused or there's other things at play. However the
general trend in the numbers seems fairly stable.