From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Np8XY-0003c5-Nj for qemu-devel@nongnu.org; Tue, 09 Mar 2010 18:08:40 -0500 Received: from [199.232.76.173] (port=40138 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Np8XX-0003al-3R for qemu-devel@nongnu.org; Tue, 09 Mar 2010 18:08:39 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1Np8XV-0005uC-Fq for qemu-devel@nongnu.org; Tue, 09 Mar 2010 18:08:38 -0500 Received: from mail-gx0-f209.google.com ([209.85.217.209]:44263) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Np8XV-0005ty-4t for qemu-devel@nongnu.org; Tue, 09 Mar 2010 18:08:37 -0500 Received: by gxk1 with SMTP id 1so2648941gxk.16 for ; Tue, 09 Mar 2010 15:08:36 -0800 (PST) Message-ID: <4B96D4F1.80405@codemonkey.ws> Date: Tue, 09 Mar 2010 17:08:33 -0600 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH 0/3]: BLOCK_WATERMARK QMP event References: <1268175216-3600-1-git-send-email-lcapitulino@redhat.com> In-Reply-To: <1268175216-3600-1-git-send-email-lcapitulino@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luiz Capitulino Cc: kwolf@redhat.com, uril@redhat.com, qemu-devel@nongnu.org On 03/09/2010 04:53 PM, Luiz Capitulino wrote: > Hi, > > This series is based on a previous series submitted by Uri Lublin: > > http://lists.gnu.org/archive/html/qemu-devel/2009-03/msg00864.html > > Details on the patches, except for this question: does it make sense to have > a 'low' watermark for block devices? > > I think it doesn't, then the event (and the monitor accompanying command) > should be called BLOCK_HIGH_WATERMARK. But this makes the event very > unflexible, so I have called it BLOCK_WATERMARK and added parameters for the > high/low watermark type. > The alternative way to implement this is for a management tool to just poll the allocated disk size periodically. It's no more/less safe than generating an event on a "watermark" because the event is still racy with respect to a guest that's writing very quickly to the disk. Regards, Anthony Liguori > It's a machine protocol, so I don't think the additional parameter > matters much. > > >