Messages in this thread | | | Date | Mon, 24 Jul 2017 17:16:30 +0200 | From | Peter Zijlstra <> | Subject | [PATCH 0/3] lib/int_sqrt: Fix, optimize and document |
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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.
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