From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [RFC][PATCH 12/12] PM / r8169: Add simplified run-time PM support Date: Mon, 4 Jan 2010 09:31:08 +0100 Message-ID: <20100104083108.GD1372@ucw.cz> References: <200911160047.46299.rjw@sisk.pl> <201001022149.05553.rjw@sisk.pl> <20100103195544.GC11928@elf.ucw.cz> <201001032201.14087.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <201001032201.14087.rjw@sisk.pl> Sender: linux-pci-owner@vger.kernel.org To: "Rafael J. Wysocki" Cc: pm list , LKML , Linux PCI , ACPI Devel Maling List , Alan Stern , Jesse Barnes , Matthew Garrett , Oliver Neukum , Shaohua Li , Bjorn Helgaas , Francois Romieu , Len Brown List-Id: linux-acpi@vger.kernel.org > > > Using /proc/acpi/battery/BAT1/state I measured the energy drawn in 10 minutes > > > both with the network adapter in D0 and D3hot. The results were that with the > > > network adapter in D0 the box drew 2476 mWh, while with the network adapter in > > > D3hot it drew 2361 mWh. The difference is 115 mWh, or about 5% on this > > > particular box. > > > > > > This means about 0.1 Wh in 10 minutes, so we can save about 0.6 Wh per hour. > > > > Which means it saves 0.6W :-). Measuring power in Wh/h is "interesting". > > You can't save power, you can only save energy. Wh is just an energy unit. Of course we can save power, you just did :-). (And in some cases -- data centers, limited cooling -- you are limited by power, not energy. You are right that on notebooks, energy is more important.) Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html