From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754098Ab2AWVDf (ORCPT ); Mon, 23 Jan 2012 16:03:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:1366 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753947Ab2AWVDe (ORCPT ); Mon, 23 Jan 2012 16:03:34 -0500 Date: Mon, 23 Jan 2012 16:03:27 -0500 From: Vivek Goyal To: Tejun Heo Cc: Lennart Poettering , axboe@kernel.dk, ctalbott@google.com, rni@google.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 08/17] blkcg: shoot down blkio_groups on elevator switch Message-ID: <20120123210327.GO25986@redhat.com> References: <20120123155216.GF25986@redhat.com> <20120123155745.GD12652@google.com> <20120123161042.GG25986@redhat.com> <20120123161619.GE12652@google.com> <20120123162553.GI25986@redhat.com> <20120123171049.GH12652@google.com> <20120123182745.GK25986@redhat.com> <20120123184336.GI12652@google.com> <20120123204352.GB21822@tango.0pointer.de> <20120123204757.GM12652@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120123204757.GM12652@google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 23, 2012 at 12:47:57PM -0800, Tejun Heo wrote: > Hello, Lennart. > > On Mon, Jan 23, 2012 at 09:43:52PM +0100, Lennart Poettering wrote: > > I didn't really follow the whole discussion here, but if this is about > > adjusting parameters of a block device as the block device shows up this > > must necessarily happen in an udev rule (and not in a daemon watching > > block devices using libudev), since you most likely need the > > synchronicity: i.e. you want to avoid that normal (libudev-using) > > userspace code ever sees the device before those params are written to > > the device. A daemon asynchronously watching the devices with libudev > > for adjusting such tunables is necessarily racy. > > Yeap, this needs to be synchronous so that it's configured before the > rest of system notices the device. Vivek, can you please ask the > tuned guys to take a look? Sure I will. Thanks. Vivek