From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: Generic battery interface Date: Fri, 28 Jul 2006 14:25:08 +0200 Message-ID: <20060728122508.GC4158@elf.ucw.cz> References: <41840b750607271332q5dea0848y2284b30a48f78ea7@mail.gmail.com> <20060727232427.GA4907@suse.cz> <41840b750607271727q7efc0bb2q706a17654004cbbc@mail.gmail.com> <20060728074202.GA4757@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from gprs189-60.eurotel.cz ([160.218.189.60]:6346 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S1161131AbWG1MZY (ORCPT ); Fri, 28 Jul 2006 08:25:24 -0400 Content-Disposition: inline In-Reply-To: <20060728074202.GA4757@suse.cz> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Vojtech Pavlik Cc: Shem Multinymous , "Brown, Len" , Matthew Garrett , kernel list , linux-thinkpad@linux-thinkpad.org, linux-acpi@vger.kernel.org Hi! > > >The applets that were doing it (yes, up to 100 times per second) > > >corrected their ways pretty quickly, because some machines became > > >unusable with the applet enabled. > > > > Exactly -- and they've been working merrily ever since. > > And if you don't want to trust applet developers, cache the latest > > reads and refresh them only if X jiffies have passed. > > The timer interrupt still has to happen every time their select() or > sleep() expires, with the system having to wake up, even when nothing > happened. Polling from userspace is bad. I do not understand this. Any polling (in kernel or in userspace) will wake the CPU, wasting power. OTOH "high/low/very low" battery applet can reasonably query battery every 5 minutes, while detailed, graphical thingie displaying the current power consumption will probably poll every 10 seconds... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html