Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752809Ab0DIN36 (ORCPT ); Fri, 9 Apr 2010 09:29:58 -0400 Received: from mailservice.tudelft.nl ([130.161.131.5]:58190 "EHLO mailservice.tudelft.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752271Ab0DIN35 (ORCPT ); Fri, 9 Apr 2010 09:29:57 -0400 X-Spam-Flag: NO X-Spam-Score: -14.389 Message-ID: <4BBF2BD1.5050107@tremplin-utc.net> Date: Fri, 09 Apr 2010 15:29:53 +0200 From: =?ISO-8859-1?Q?=C9ric_Piel?= User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100331 Mandriva/3.0.4-1mdv2010.1 (2010.1) Thunderbird/3.0.4 MIME-Version: 1.0 To: Jiri Kosina CC: Andrew Morton , Samu Onkalo , Pavel Machek , lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, Marcin Derlukiewicz Subject: Re: [PATCH] lis3lv02d: provide means to disable polled input interface References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1432 Lines: 31 On 09/04/10 14:56, Jiri Kosina wrote: > lis3lv02d driver creates emulated joystick interface for events reported > by the sensor. > Because of HW, this has to be implemented as polled input device, with > 20Hz frequency. > > 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? Cheers, Eric -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/