linux-kernel - Re: [PATCH 06/12] hdaps: Limit hardware query rate

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Date:	Tue, 8 Aug 2006 12:08:39 +0000
From:	Pavel Machek <pavel@...e.cz>
To:	Shem Multinymous <multinymous@...il.com>
Cc:	Robert Love <rlove@...ve.org>, Jean Delvare <khali@...ux-fr.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	linux-kernel@...r.kernel.org, hdaps-devel@...ts.sourceforge.net
Subject: Re: [PATCH 06/12] hdaps: Limit hardware query rate

Hi!

> The current hdaps driver queries the hardware on (almost) any sysfs read.
> Since fresh readouts are genereated by the hardware at a constant rate,
> this means apps are eating each other's events. Also, polling multiple
> attributes will genereate excessive hardware queries and excessive CPU
> load due to the duration of the hardware query transaction.
> 
> With this patch, the driver will normally update its cached readouts
> only in its timer function (which exists anyway, for the input device).
> If that read failed, it will be retried upon the actual sysfs access.
> In all cases, query rate is bounded and apps will get reasonably
> fresh and usually cached readouts.
> 
> The polling rate is increased to 50Hz, as needed by the hdaps daemon.
> A later patch makes this configurable.
> 
> Signed-off-by: Shem Multinymous <multinymous@...il.com>

I'd insert fewer blank lines, otherwise patch looks ok to me.

Signed-off-by: Pavel Machek <pavel@...e.cz>

-- 
Thanks for all the (sleeping) penguins.
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