From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robert Hancock Subject: Re: libata timeouts when stressing a Samsung HDD Date: Wed, 11 Feb 2009 22:28:45 -0600 Message-ID: <4993A57D.6010107@gmail.com> References: <20090202164053.4ecca9dd@dhcp-100-2-144.bos.redhat.com> <49922A2D.508@kernel.org> <49924F48.4000009@rtr.ca> <20090211152908.383744cd@dhcp-100-2-144.bos.redhat.com> <49934B20.4060206@rtr.ca> <49934D24.1050204@garzik.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from rn-out-0910.google.com ([64.233.170.191]:50038 "EHLO rn-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752359AbZBLE2v (ORCPT ); Wed, 11 Feb 2009 23:28:51 -0500 Received: by rn-out-0910.google.com with SMTP id k40so604403rnd.17 for ; Wed, 11 Feb 2009 20:28:49 -0800 (PST) In-Reply-To: <49934D24.1050204@garzik.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik Cc: Mark Lord , Chuck Ebbert , Tejun Heo , linux-ide@vger.kernel.org Jeff Garzik wrote: > Mark Lord wrote: >> I wonder if it's just a case of too short a timeout on the cache flushes? > > The answer in general to this question has always been "yes"..... > > Unless this has changed in the past year, the worst case for SATA cache > flush can definitely exceed 30 seconds... it is unbounded as defined in > the spec, and unbounded in practice as well. > > Of course, users' patience is not unbounded :) Yeah, it's pretty ludicrous for a cache flush to potentially take that long. Theoretically if you had a 32MB write cache completely full with completely non-contiguous sectors you could end up with it taking something like 2 minutes or more to write out. However, the drive really should be ensuring that it doesn't build up so much in the write cache that a flush would takes this long - that is a lot of data that could be lost on an unexpected power-off. However, in this case the drive is not reporting Busy status at the timeout, which suggests maybe an interrupt got lost or something. (Could be still the drive's fault.) Chuck, when this happens can you tell if the disk sounds like it is grinding away until the timeout happens or is it just sitting there?