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Date: Mon, 24 Jul 2017 17:16:30 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: torvalds@linux-foundation.org, akpm@linux-foundation.org
Cc: dave@stgolabs.net, aksgarg1989@gmail.com, tglx@linutronix.de,
        mingo@kernel.org, will.deacon@arm.com, joe@perches.com,
        peterz@infradead.org, linux-kernel@vger.kernel.org
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.