On Wed, Sep 30, 2009 at 10:55:24AM +0200, Dietmar Maurer wrote:
> Another problem occur when max_downtime is too short. This can results in never ending migration task.
>
> To reproduce just play a video inside a VM and set max_downtime to 30ns
>
> Sure, one can argument that this behavior is expected.
>
> But the following would avoid the problem:
>
> + if ((stage == 2) && (bytes_transferred > 2*ram_bytes_total())) {
> + return 1;
> + }
why 2 * ?
This means we'll have to transfer the whole contents of RAM at least twice to hit this condition, right?
>
> Or do you think that is not reasonable?
>
> - Dietmar
>
> > -----Original Message-----
> > From: Glauber Costa [mailto:glommer@xxxxxxxxxx]
> > Sent: Mittwoch, 30. September 2009 06:49
> > To: Dietmar Maurer
> > Cc: Anthony Liguori; kvm
> > Subject: Re: migrate_set_downtime bug
> >
> > On Tue, Sep 29, 2009 at 06:36:57PM +0200, Dietmar Maurer wrote:
> > > > Also, if this is really the case (buffered), then the bandwidth
> > capping
> > > > part
> > > > of migration is also wrong.
> > > >
> > > > Have you compared the reported bandwidth to your actual bandwith ?
> > I
> > > > suspect
> > > > the source of the problem can be that we're currently ignoring the
> > time
> > > > we take
> > > > to transfer the state of the devices, and maybe it is not
> > negligible.
> > > >
> > >
> > > I have a 1GB network (e1000 card), and get values like bwidth=0.98 -
> > which is much too high.
> > The main reason for not using the whole migration time is that it can
> > lead to values
> > that are not very helpful in situation where the network load changes
> > too much.
> >
> > Since the problem you pinpointed do exist, I would suggest measuring
> > the average load of the last,
> > say, 10 iterations. How would that work for you?
>
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