Only the scheduler knows which job will start next so only the scheduler
can give the estimated response time. Maui provides
showstart [JOB]
http://www.clusterresources.com/products/maui/docs/commands/showstart.shtml
This gives the best guess at the start time for the job. The only possible
improvement on this could come from Jeff's method but this is a 2nd order
effect. Every other scheme of counting free cpus, queued job, total cpus
is bound to fail when using an educated scheduler with a site policy.
So the ERT is the showstart time of the last job in the queue. This
assumes all jobs in a queue are equal(FIFO). If there are no queueing jobs
then ERT=0.
Cheers,
Rod.
On Fri, 11 Feb 2005, Steve Traylen wrote:
> On Fri, Feb 11, 2005 at 07:33:35AM -0800 or thereabouts, Rod Walker wrote:
> > Hi,
> > How does this give anything useful at all? This is the estimated response
> > time for pbs:
> > $MaxTime=(($TotalJobs * $WallTime) - $UsedTime) / $TCPU;
> > where TCPU is the smaller of total number of cpus or the max running jobs.
>
> The old one used to have
>
> if ( $queuedJobs = 0 ) {
> ETT=0
> }
>
> which was good, I see it as clear that if you are not queuing a job
> for someone then chances are you will run a job from them immediately.
>
> The only rule that really matters is that ETT must go up for a queue
> as soon as you start to queue jobs in that queue. Until a job is queued
> ETT should not go up at all. I would say these two things should
> be true for any calculation that use.
>
> See.
> https://savannah.cern.ch/bugs/?func=detailitem&item_id=6213
>
> where this is being commented on.
>
> Steve
>
> >
> > Our cluster has 18 cpus and 2 jobs in the atlas queue, with a combined
> > used wall time of around 72 hours. The max walltime is 72 hrs. So
> > $MaxTime=((2*72)-72)/18=4hours
> > Give or take, this is what lcgce01.triumf.ca is publishing, but it clearly
> > should be zero as there are 16 free cpus.
> > I know it difficult to get a consistent estimation of ERT for both full
> > and empty grids, but is this really the best estimate?
> >
> > I know the logic, if freecpus>0 then ERT=0, does not work due to site
> > policies. How about setting ERT=0 if there are no jobs queued for that
> > CE(queue)? This will only be wrong when the site is exactly full, which
> > almost never happens. Otherwise do your stuff with used times.
> >
> > Or maybe, if no jobs queued and freecpus>0 ...
> > Ideally there is some way to extract the estimate from Maui, as this is
> > the only truth. MOAB has a 'showstart' command for example.
> >
> > Cheers,
> > Rod.
> >
> >
> >
> > --
> > Rod Walker +1 6042913051
>
> --
> Steve Traylen
> [log in to unmask]
> http://www.gridpp.ac.uk/
>
--
Rod Walker +1 6042913051
