From: Peter Zijlstra <peterz@infradead.org>
To: Kees Cook <keescook@chromium.org>
Cc: Joe Perches <joe@perches.com>, Michael Davidson <md@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
David Miller <davem@davemloft.net>,
Matthew Wilcox <mawilcox@microsoft.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] lib/int_sqrt.c: optimize for small argument values
Date: Fri, 20 Oct 2017 18:22:27 +0200 [thread overview]
Message-ID: <20171020162227.GE6524@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <CAGXu5jL6g3QU4QshBiD=Zhf-5NJFX99eJ1sMkdOwn3ywW41TTA@mail.gmail.com>
On Fri, Oct 20, 2017 at 07:18:51AM -0700, Kees Cook wrote:
> On Thu, Oct 19, 2017 at 11:13 PM, Joe Perches <joe@perches.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?
Oh, crud, forgot all about it. I'd have to double check I addressed the
concerns Linus had with my Changelogs, but other than that he seemed to
be OK.
prev parent reply other threads:[~2017-10-20 16:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-19 20:31 [PATCH] lib/int_sqrt.c: optimize for small argument values Michael Davidson
2017-10-19 20:42 ` Kees Cook
2017-10-19 20:56 ` Jason A. Donenfeld
2017-10-19 21:04 ` Kees Cook
2017-10-20 6:13 ` Joe Perches
2017-10-20 14:18 ` Kees Cook
2017-10-20 16:22 ` Peter Zijlstra [this message]
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