linux-kernel - Re: [PATCH v6] Add generic exponentially weighted moving average (EWMA) function

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Date:	Sun, 14 Nov 2010 09:51:08 +0100
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
CC:	Bruno Randolf <br1@...fach.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	randy.dunlap@...cle.com, peterz@...radead.org, blp@...stanford.edu,
	linux-kernel@...r.kernel.org, Lars_Ericsson@...ia.com,
	kevin.granade@...il.com,
	"John W. Linville" <linville@...driver.com>
Subject: Re: [PATCH v6] Add generic exponentially weighted moving average
 (EWMA) function

KOSAKI Motohiro wrote:
>>> Why do ewma_init() and ewma_add() return their first argument?  They look
>>> to me like they can be straight-forward void functions.
>> You are right, for ewma_init() it does not make sense.
>>
>> For ewma_add() I think it does. This has been discussed before (e.g. 
>> http://linux.derkeiler.com/Mailing-Lists/Kernel/2010-10/msg09124.html).
>> Some people might want to get the value when they add a sample by using 
>> ewma_get(ewma_add(&ewma, val));
> 
> 	ewma_add(&ewma, val);
> 	ewma_get(&ewma);
> 
> is enough simpler and cleaner. I don't oppse this :)

There are more candidate colors for the bike shed: :-)
  - an ewma_add_return could do what ewma_get(ewma_add(...)) is meant for,
  - or ewma_add itself could return the result.

BTW, isn't "get" more usually used as a prefix for these kinds of functions in
kernel APIs?  "get" as a suffix more often means "get a reference" alias
increase reference count rather than "get the value".
-- 
Stefan Richter
-=====-==-=- =-== -===-
http://arcgraph.de/sr/
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