Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753574AbZKSOfG (ORCPT ); Thu, 19 Nov 2009 09:35:06 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752729AbZKSOfF (ORCPT ); Thu, 19 Nov 2009 09:35:05 -0500 Received: from gv-out-0910.google.com ([216.239.58.186]:36416 "EHLO gv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751598AbZKSOfD (ORCPT ); Thu, 19 Nov 2009 09:35:03 -0500 MIME-Version: 1.0 In-Reply-To: <20091119143008.GA719@srcf.ucam.org> References: <20091118195342.GA13627@srcf.ucam.org> <20091118200712.GA14026@srcf.ucam.org> <20091118213355.GA16630@srcf.ucam.org> <20091119130107.GB20949@srcf.ucam.org> <20091119141634.GA311@srcf.ucam.org> <20091119143008.GA719@srcf.ucam.org> From: Kay Sievers Date: Thu, 19 Nov 2009 15:34:53 +0100 Message-ID: Subject: Re: [PATCH] [RFC] Add support for uevents on block device idle changes To: Matthew Garrett Cc: David Zeuthen , linux-kernel@vger.kernel.org, axboe@kernel.dk, linux-hotplug@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1335 Lines: 27 On Thu, Nov 19, 2009 at 15:30, Matthew Garrett wrote: > On Thu, Nov 19, 2009 at 03:25:59PM +0100, Kay Sievers wrote: >> On Thu, Nov 19, 2009 at 15:16, Matthew Garrett wrote: >> > It could, but it seems a bit of a hack. It'd still also require the >> > timer to be in the kernel, so we might as well expose that to userspace. >> >> Sure, but a userspace configurable policy for an in-kernel disk-idle >> powermanagent sounds fine, compared to a single-subscriber >> userspace-only disk-idle event interface. :) > > Well, we still need to expose this for the access pattern modifying. I > really don't see the issue with the single subscriber being devkit-disks > - none of the operations involved are atomic, so we're inherently racy > here. Single-subscriber event interfaces are usually a no-go for generic infrastructure like this. We still have the unmodified HAL running until it is dead, and this works only because there are no such awkward interfaces. In a few years we will probably have diskfoo replacing dk-disks, and then ... :) Kay -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/