linux-kernel - Re: [RFC] lib/vsprintf.c: Even faster decimal conversion

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Date:	Thu, 05 Mar 2015 08:03:33 -0800
From:	Joe Perches <joe@...ches.com>
To:	Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:	linux-kernel@...r.kernel.org,
	"Peter Zijlstra (Intel)" <peterz@...radead.org>,
	Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC] lib/vsprintf.c: Even faster decimal conversion

On Thu, 2015-03-05 at 16:22 +0100, Rasmus Villemoes wrote:
> On Sat, Feb 21 2015, Rasmus Villemoes <linux@...musvillemoes.dk> wrote:
> 
> > [...] decimal conversion [...] it does indeed seem like there is
> > something to be gained, especially on 64 bits.
> >
> > $ ./test64
> > Distribution              Function         Cycles/conv  Conv/1 sec
> > uniform([10, 2^64-1])     linux_put_dec          127.72         23047567
> > uniform([10, 2^64-1])     rv_put_dec              60.73         45932786
> >                           +/-                   -52.45%          +99.30%
> [...]
> > 3 + neg_binom(0.50)       linux_put_dec           16.85        159560933
> > 3 + neg_binom(0.50)       rv_put_dec              12.59        204607570
> >                           +/-                   -25.31%          +28.23%
> 
> I'm assuming the underwhelming response means NAK.

Dunno why you assume that, sometimes it just takes
awhile for people to look at non-critical, infrequent
optimization changes like this.

Seems sensible enough to me though.

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