From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: Disk spin-up optimization during system resume Date: Sat, 18 Jan 2014 09:04:39 -0500 Message-ID: <20140118140439.GC3640@htj.dyndns.org> References: <20140117202433.GB23024@htj.dyndns.org> <52D998C2.7080302@ubuntu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-qc0-f182.google.com ([209.85.216.182]:37305 "EHLO mail-qc0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752155AbaAROEn (ORCPT ); Sat, 18 Jan 2014 09:04:43 -0500 Received: by mail-qc0-f182.google.com with SMTP id c9so4647923qcz.27 for ; Sat, 18 Jan 2014 06:04:42 -0800 (PST) Content-Disposition: inline In-Reply-To: <52D998C2.7080302@ubuntu.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Phillip Susi Cc: Alan Stern , Dan Williams , Todd E Brandt , Aaron Lu , SCSI development list Hello, Phillip. On Fri, Jan 17, 2014 at 03:55:30PM -0500, Phillip Susi wrote: > > What kind of use cases are we expecting for the lazy behavior? > > Not all systems only have a single drive. There may be a tendency for > IO to the drive with the root fs on it after a resume, but multi drive > systems often end up not touching the other disks so they go back into > suspend shortly after resume, so the start/stop cycle was just > needless wear and tear on the drive. The problem is that the relevance of lazy behavior moves together with the frequency of suspend/resume cycles. So, it's something which could be useful for machines with multiple rotating disks which suspend and resume frequently? It's a hard sell. If it can be done trivially, and I really mean "trivially", maybe. If it involves almost any level of complexity, I'd be highly reluctant to apply the changes. Its usefulness is not only marginal now, but it'll also continue to fall rather rapidly. Adding maintenance overhead for that seems rather ill advised to me. Thanks. -- tejun