linux-kernel - Re: [PATCH 2/3] lib: Improve EWMA efficiency by using bitshifts

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Message-Id: <201012021937.44368.br1@einfach.org>
Date:	Thu, 2 Dec 2010 19:37:44 +0900
From:	Bruno Randolf <br1@...fach.org>
To:	Johannes Berg <johannes@...solutions.net>
Cc:	linville@...driver.com, randy.dunlap@...cle.com,
	peterz@...radead.org, blp@...stanford.edu,
	linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
	Lars_Ericsson@...ia.com, j@...fi, stefanr@...6.in-berlin.de,
	kosaki.motohiro@...fujitsu.com, akpm@...ux-foundation.org,
	kevin.granade@...il.com
Subject: Re: [PATCH 2/3] lib: Improve EWMA efficiency by using bitshifts

On Thu December 2 2010 19:20:22 Johannes Berg wrote:
> On Thu, 2010-12-02 at 19:12 +0900, Bruno Randolf wrote:
> > +	/* get bitshift for weight */
> > +	for (n = 0; !(weight & 1); n++)
> > +		weight = weight >> 1;
> > +	WARN_ON(weight > 1 || n < 1);
> 
> I'm sure there's something like log2() (and is_power_of_2() for the
> warning) in the kernel already -- no need to reimplement it...

Ah, thanks for that! Will resend an improved version.

bruno
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