From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261490AbVGYVZy (ORCPT ); Mon, 25 Jul 2005 17:25:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261479AbVGYVZy (ORCPT ); Mon, 25 Jul 2005 17:25:54 -0400 Received: from mustang.oldcity.dca.net ([216.158.38.3]:61830 "HELO mustang.oldcity.dca.net") by vger.kernel.org with SMTP id S261490AbVGYVZw (ORCPT ); Mon, 25 Jul 2005 17:25:52 -0400 Subject: RE: Variable ticks From: Lee Revell To: "Brown, Len" Cc: Bill Davidsen , Linux Kernel Mailing List In-Reply-To: References: Content-Type: text/plain Date: Mon, 25 Jul 2005 17:25:49 -0400 Message-Id: <1122326750.1472.46.camel@mindpipe> Mime-Version: 1.0 X-Mailer: Evolution 2.2.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2005-07-25 at 17:19 -0400, Brown, Len wrote: > >>>Question one, are there other actions to consider? > >> > >> > >> Yes. > >> Speaking for ACPI C3 state, note that DMA also > >> wakes up the CPU -- even if there was no device interrupt. > >> (aka, "the trouble with USB") > > > >Trouble? Why would USB do DMA unless there was a device activity? > > look here: > http://www.google.com/search?hl=en&q=usb+selective+suspend > > Linux is working on it too, but it is in development. What about audio? If there is a sound server running then you're going to have a constant stream of interrupts and DMA activity from the sound card even if the machine is idle and there aren't any sounds playing. Lee