From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: KVM call agenda for Apr 27 Date: Tue, 27 Apr 2010 08:15:01 -0500 Message-ID: <4BD6E355.1060107@codemonkey.ws> References: <20100426172634.GC15278@x200.localdomain> <4BD5D28C.7080700@codemonkey.ws> <20100426221258.GH15278@x200.localdomain> <4BD61584.9080208@codemonkey.ws> <4BD69D03.2050502@redhat.com> <4BD6A4CA.6070306@redhat.com> <4BD6A6BA.1090600@redhat.com> <4BD6A995.2010006@redhat.com> <4BD6ACDF.8090705@redhat.com> <4BD6AF41.2090909@redhat.com> <4BD6B12C.1010908@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: dlaor@redhat.com, Avi Kivity , Chris Wright , kvm@vger.kernel.org, qemu-devel@nongnu.org To: Kevin Wolf Return-path: Received: from mail-qy0-f179.google.com ([209.85.221.179]:41213 "EHLO mail-qy0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754613Ab0D0NP6 (ORCPT ); Tue, 27 Apr 2010 09:15:58 -0400 Received: by qyk9 with SMTP id 9so19304627qyk.1 for ; Tue, 27 Apr 2010 06:15:58 -0700 (PDT) In-Reply-To: <4BD6B12C.1010908@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 04/27/2010 04:41 AM, Kevin Wolf wrote: > Am 27.04.2010 11:32, schrieb Dor Laor: > >> On 04/27/2010 12:22 PM, Avi Kivity wrote: >> >>> On 04/27/2010 12:08 PM, Dor Laor wrote: >>> >>>> On 04/27/2010 11:56 AM, Avi Kivity wrote: >>>> >>>>> On 04/27/2010 11:48 AM, Dor Laor wrote: >>>>> >>>>>> IMHO the whole thing is way over engineered: >>>>>> a) Having another channel into qemu is complicating management >>>>>> software. Isn't the monitor should be the channel? Otherwise we'll >>>>>> need to create another QMP (or nbd like Avi suggest) for these >>>>>> actions. It's extra work for mgmt and they will have hard time to >>>>>> understand events interleaving of the various channels >>>>>> >>>>> block layer plugins allow intercepting all interesting block layer >>>>> events, not just write-past-a-watermark, and allow actions based on >>>>> those events. It's a more general solution. >>>>> >>>> No problem there, as long as we do try to use the single existing QMP >>>> with the plugins. Otherwise we'll create QMP2 for the block events in >>>> a year from now. >>>> >>> I don't see how we can interleave messages from the plugin into the qmp >>> stream without causing confusion. >>> >> Those are QMP async events. >> >> Since Kevin suggested adding even more events (was is cynical?) >> > The part about adding a scripting engine was. > > The idea of adding a generic event (one event, not even more!) for a QMP > query-* result change doesn't sound that bad on second thought, though. > It's not specific for watermarks and looks less complicated than all the > plugin, NBD and QMP2 stuff. > > It's almost the same as Anthony's polling suggestion (works with query-* > results from user perspective), just without polling. > Is this really necessary other than making people feel less bad about polling? How I understand the use case, polling every five seconds would be completely reasonable in addressing the use-case. It might not be as sexy as a generic event notification mechanism but not everything can't be JSON. Regards, Anthony Liguori > Kevin >