From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261177AbVFFFqg (ORCPT ); Mon, 6 Jun 2005 01:46:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261182AbVFFFqg (ORCPT ); Mon, 6 Jun 2005 01:46:36 -0400 Received: from smtpout.mac.com ([17.250.248.72]:26561 "EHLO smtpout.mac.com") by vger.kernel.org with ESMTP id S261177AbVFFFqe (ORCPT ); Mon, 6 Jun 2005 01:46:34 -0400 In-Reply-To: <1117966262.5027.9.camel@localhost.localdomain> References: <20050601195922.GA589@openzaurus.ucw.cz> <1117966262.5027.9.camel@localhost.localdomain> Mime-Version: 1.0 (Apple Message framework v728) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: Cc: Pavel Machek , Roy Keene , linux-kernel@vger.kernel.org Content-Transfer-Encoding: 7bit From: Kyle Moffett Subject: Re: Problem with 2.6 kernel and lots of I/O Date: Mon, 6 Jun 2005 01:46:18 -0400 To: Erik Slagter X-Mailer: Apple Mail (2.728) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Jun 5, 2005, at 06:11:02, Erik Slagter wrote: > On Wed, 2005-06-01 at 21:59 +0200, Pavel Machek wrote: > >>> Start RAID in degraded mode with remote device (nbd1) >>> Hot-add local device (nbd0) >> >> Stop right here. You may not use nbd over loopback. > > Any specific reason (just curious)? IIRC, because of the way the loopback delivers packets from the same context as they are sent, it is possible (and quite easy) to either deadlock or peg the CPU and make everything hang and be unuseable. DRBD likewise used to have problems with testing over the loopback until they added a special configuration option to be extra careful and yield CPU. Cheers, Kyle Moffet