From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [ugly patch] Save .15W-.5W by AHCI powersaving Date: Mon, 25 Feb 2008 17:42:58 -0500 Message-ID: <47C34472.3090706@garzik.org> References: <20080225134558.GA1611@elf.ucw.cz> <47C34081.5090205@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:36324 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753739AbYBYWnF (ORCPT ); Mon, 25 Feb 2008 17:43:05 -0500 In-Reply-To: <47C34081.5090205@rtr.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Lord Cc: Pavel Machek , kernel list , Linux-pm mailing list , stern@rowland.harvard.edu, linux-ide@vger.kernel.org Mark Lord wrote: > Pavel Machek wrote: >> This is a patch (very ugly, assumes you have just one disk) to bring >> powersaving to AHCI. You need Alan's SCSI autosuspend (attached) patch >> as a base. >> >> It saves .5W compared to config with disk spinning, and even .15W >> compared to hdparm -y... on my thinkpad x60 anyway. > .. > > There was a discussion of this here today. > It makes good use of AHCI-specific features. > > Has it been tested with a Port-Multiplier yet? > > This is cool enough that we really ought to do a hardware-independent > version, so that all SATA interfaces could benefit. Especially ata_piix, > but others too. BTW we can also save power by allowing the user to choose to disable hotplugging support. Then we can power down PHYs that are not in use. That requires the addition of some policy controls, because it is user-specific whether or not to waste power waiting for a plug-in event. Jeff