From mboxrd@z Thu Jan  1 00:00:00 1970
From: Glauber Costa <glommer@redhat.com>
Subject: Re: migrate_set_downtime bug
Date: Mon, 5 Oct 2009 12:32:06 -0300
Message-ID: <20091005153206.GE8092@mothafucka.localdomain>
References: <20090930044832.GA5149@mothafucka.localdomain> <90D306BE6EBC8D428A824FBBA7A3113DFDCDF184@ronja.maurer-it.com> <20090930112328.GB5149@mothafucka.localdomain> <90D306BE6EBC8D428A824FBBA7A3113DFDCDF18D@ronja.maurer-it.com> <20090930163951.GD5149@mothafucka.localdomain> <90D306BE6EBC8D428A824FBBA7A3113DFDCDF18E@ronja.maurer-it.com> <4AC9E3DA.6000607@redhat.com> <20091005130409.GD8092@mothafucka.localdomain> <4AC9F1E4.4070101@redhat.com> <90D306BE6EBC8D428A824FBBA7A3113D010EFFE8EB@ronja.maurer-it.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Avi Kivity <avi@redhat.com>,
	Anthony Liguori <anthony@codemonkey.ws>,
	kvm <kvm@vger.kernel.org>
To: Dietmar Maurer <dietmar@proxmox.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mx1.redhat.com ([209.132.183.28]:44430 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752958AbZJEPck (ORCPT <rfc822;kvm@vger.kernel.org>);
	Mon, 5 Oct 2009 11:32:40 -0400
Content-Disposition: inline
In-Reply-To: <90D306BE6EBC8D428A824FBBA7A3113D010EFFE8EB@ronja.maurer-it.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On Mon, Oct 05, 2009 at 04:09:43PM +0200, Dietmar Maurer wrote:
> > Heuristics like number of pages, maybe.  But since we don't export
> > iteration information, we can't expect management tools to stop the
> > guest if migration doesn't converge.
> > 
> > I suppose it could issue a 'stop' after some amount of time (constant *
> > memory size / bandwidth).
> 
> 'bandwidth' is something that changes dynamically (or by user settings), so why don't we simply abort after some amount of transferred memory (constant * memory size). This can be implemented by the management application without problems, although it's much easier inside kvm.
> 
Easier, yes.

But then once it is done, people wanting a different behaviour for some valid reason are stuck with that.
This is the very reason we expose information about migration in the monitor to begin with.

Again, I believe the fix for this convergence problem does not belong here.