linux-kernel - Re: [PATCH v3] Add generic exponentially weighted moving average (EWMA) function

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Message-Id: <201010220953.30148.br1@einfach.org>
Date:	Fri, 22 Oct 2010 09:53:30 +0900
From:	Bruno Randolf <br1@...fach.org>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	randy.dunlap@...cle.com, akpm@...ux-foundation.org,
	kevin.granade@...il.com, Lars_Ericsson@...ia.com,
	blp@...stanford.edu, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] Add generic exponentially weighted moving average (EWMA) function

On Thu October 21 2010 19:31:47 KOSAKI Motohiro wrote:
> Hi
> 
> I'm plaing this a bit and I have to say this doesn't works as I expected
> because ewma_init() has very easy confusable.
> 
> so, I have one request.
> 
> > +/**
> > + * ewma_init() - Initialize EWMA parameters
> > + * @avg: Average structure
> > + * @factor: Factor to use for the scaled up internal value. The maximum
> > value + *	of averages can be UINT_MAX/(factor*weight).
> > + * @weight: Exponential weight, or decay rate. This defines how fast the
> > + * 	influence of older values decreases. Has to be bigger than 1.
> > + *
> > + * Initialize the EWMA parameters for a given struct ewma @avg.
> > + */
> > +struct ewma*
> > +ewma_init(struct ewma *avg, const unsigned int factor,
> > +	  const unsigned int weight)
> > +{
> > +	WARN_ON(weight <= 1 || factor == 0);
> > +	avg->weight = weight;
> > +	avg->factor = factor;
> > +	return avg;
> > +}
> > +EXPORT_SYMBOL(ewma_init);
> 
> Please initalize avg->internal too.

Oh, sorry! I forgot that!
 
> and nit, I don't understand what you intend by 'const unsigned int'. I
> think we can remove this const safely. it's more easy readable.

O.K. Will resend.

Apart from that, what didn't work as you expected?

Bruno
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