[Swift-devel] Re: replication vs site score

[Mihael Hategan]

On Wed, 2009-04-08 at 13:46 -0700, Ioan Raicu wrote:
> 
> 
> Mihael Hategan wrote: 
> > > The place where the queue prediction doesn't help, is when there is a
> > > bad node which causes an application to be slow or fail.
> > >     
> > 
> > No. The prediction doesn't help when it fails to predict accurately.
> > 
> >   
> The prediction that I was referring to was only for the queue time,
> not the execution time. A failed node, causing an application run time
> to be longer than expected, has no impact on the prediction of the
> wait queue time. 

You're right. I was trying to say that fundamentally the problem of
uncertainty in queue times will remain by virtue of the fact that the
times when people submit jobs (as well as the amount of jobs) is
unpredictable and it can affect other people's job queue times. 

The predictor in the paper answers the question "if you were to submit
your job before the state of the queue changes in any way, what would be
the expected queue time for the job" and not "what will be the queue
time for the job".