From mboxrd@z Thu Jan 1 00:00:00 1970 From: Elias Oltmanns Subject: Re: Laptop shock detection and harddisk protection Date: Wed, 17 Sep 2008 17:21:01 +0200 Message-ID: <87d4j2ol2a.fsf@denkblock.local> References: <48C7FCEE.8060404@kernel.org> <41840b750809110908o54a61f55w7b1b9793abf55634@mail.gmail.com> <48C948A6.3080404@kernel.org> <877i9ipi56.fsf@denkblock.local> <20080817195103.GD4043@ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from nebensachen.de ([195.34.83.29]:59298 "EHLO mail.nebensachen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752628AbYIQPVL (ORCPT ); Wed, 17 Sep 2008 11:21:11 -0400 In-Reply-To: <20080817195103.GD4043@ucw.cz> (Pavel Machek's message of "Sun, 17 Aug 2008 21:51:03 +0200") Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Pavel Machek Cc: Tejun Heo , Shem Multinymous , Thomas Renninger , Linux Kernel Mailing List , IDE/ATA development list Pavel Machek wrote: > Hi! > >> Short of a satisfying proposition regarding the questions raised, I just >> want to add two things that would be nice to solve in the future one way >> or another and should perhaps be taken into consideration from the >> beginning: >> >> 1. Disable polling completely when it isn't required: once the hd has >> spun down, there is no need to keep polling the sensors at all. Only >> when the first request requiring the hd to spin up arrives, the >> kernel needs to hold back for a short while to gather enough data >> from the sensors, so shock protection is up and running again. > > hdparm can already tell if disk is spinning or not. As userland is > polling, already, that may be enough? Yes, I know it *is* possible, I just think it may not be completely trivial to get it right. The only way I can think of, right now, is some sort of polling in the hdparm way, i.e. issuing a ATA_CMD_CHK_POWER from time to time. The question is how we are to decide when and how often we should poll for the current power state of the HD. > >> 2. Make shock protection interact nicely with suspend operations: >> currently, we are out of luck if anything should happen after >> processes have been frozen. This is particularly unfortunatel in the >> case of s2disk. > > I'd say that s2disk is similar to early boot... no protection there. Well, this is true for resume. However, I can't help thinking that we may do better than that until the disk spins down, particularly while writing the image to disk. Regards, Elias