From: <samu.p.onkalo@nokia.com>
To: <marcin@derlukiewicz.pl>, <jkosina@suse.cz>, <eric.piel@tremplin-utc.net>
CC: <akpm@linux-foundation.org>, <pavel@ucw.cz>, <lm-sensors@lm-sensors.org>,
       <linux-kernel@vger.kernel.org>
Date: Fri, 16 Apr 2010 14:00:15 +0200
Subject: RE: [PATCH] lis3lv02d: provide means to disable polled input
 interface
Thread-Topic: [PATCH] lis3lv02d: provide means to disable polled input
 interface
Thread-Index: AcrdWd0DseU83KcJTquojGMiu9I2dgAAh6MA
Message-ID: <62697B07E9803846BC582181BD6FB6B826A8525E8A@NOK-EUMSG-02.mgdnok.nokia.com>
References: <alpine.LNX.2.00.1004091453530.8345@pobox.suse.cz>
 <4BBF2BD1.5050107@tremplin-utc.net>
 <alpine.LNX.2.00.1004091532150.8345@pobox.suse.cz>
 <op.va86rulwgp7y00@linux-r26l.site>
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>-----Original Message-----
>From: ext Marcin Derlukiewicz [mailto:marcin@derlukiewicz.pl]
>Sent: 16 April, 2010 14:42
>To: Jiri Kosina; Éric Piel
>Cc: Andrew Morton; Onkalo Samu.P (Nokia-D/Tampere); Pavel Machek; lm-
>sensors@lm-sensors.org; linux-kernel@vger.kernel.org
>Subject: Re: [PATCH] lis3lv02d: provide means to disable polled input
>interface
>
>Dnia 09-04-2010 o 15:32:59 Jiri Kosina <jkosina@suse.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
>

Could you check what is the polling period of the device.
something like:
cat /sys/devices/platform/lis3lv02d/input/input9/poll

it is current polling period in milliseconds. 0 disables polling.

-Samu

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