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Date: Fri, 20 Oct 2017 07:18:51 -0700 From: Kees Cook <keescook@...omium.org> To: Joe Perches <joe@...ches.com>, Peter Zijlstra <peterz@...radead.org> Cc: Michael Davidson <md@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>, Ingo Molnar <mingo@...nel.org>, David Miller <davem@...emloft.net>, Matthew Wilcox <mawilcox@...rosoft.com>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] lib/int_sqrt.c: optimize for small argument values On Thu, Oct 19, 2017 at 11:13 PM, Joe Perches <joe@...ches.com> wrote: > On Thu, 2017-10-19 at 13:31 -0700, Michael Davidson wrote: >> int_sqrt() currently takes approximately constant time >> regardless of the value of the argument. By using the >> magnitude of the operand to set the initial conditions >> for the calculation the cost becomes proportional to >> log2 of the argument with the worst case behavior not >> being measurably slower than it currently is. > > https://lkml.org/lkml/2017/7/24/408 Ah! Cool. I don't see this version queued up for -next. Where does Peter's version stand? -Kees -- Kees Cook Pixel Security
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