linux-kernel - Re: [PATCH] lis3lv02d: provide means to disable polled input interface

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Date:	Fri, 16 Apr 2010 13:41:49 +0200
From:	"Marcin Derlukiewicz" <marcin@...lukiewicz.pl>
To:	"Jiri Kosina" <jkosina@...e.cz>,
	Éric Piel <eric.piel@...mplin-utc.net>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Samu Onkalo" <samu.p.onkalo@...ia.com>,
	"Pavel Machek" <pavel@....cz>, lm-sensors@...sensors.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lis3lv02d: provide means to disable polled input
 interface

Dnia 09-04-2010 o 15:32:59 Jiri Kosina <jkosina@...e.cz> napisał(a):

> On Fri, 9 Apr 2010, Éric Piel wrote:
>
>> > This is reported to create 20% CPU usage increase (and proportionaly  
>> higher
>> > power consumption) just for the ipolldevd kernel thread (which is used
>> > to read the sensor).
>> >
>> > As most users probably only use the freefall functionality of the  
>> driver
>> > and not the joystick interface, provide means for disabling the  
>> registration
>> > of joystick device altogether via module parameter.
>> > (I'd rather make it default to 0, but this will break backwards  
>> compatibility).
>> Are you saying there is a 20% CPU usage even when the joystick interface
>> is not open? This should not happen (and this is not happening on my
>> laptop). The polling should happen only when a userspace app opens the
>> joystick interface (like running neverball).
>>
>> So I'd tend to think it's more due to a misconfiguration of the system
>> (like xserver using the joystick interface as a pointer device) or it's
>> a bug in the way we set up the polling. Could you investigate and let me
>> know?
>
> Marcin originally reported this to me.
>
> Marcin, could you please check 'lsof' output to see whether the joystick
> interface has been open by some application?
>
> Thanks,
>

sorry for the delay, had a crunch time

here is the link for this lsof:
https://bugzilla.novell.com/attachment.cgi?id=354953


Best regards,
Marcin.
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