[Simgrid-user] SimDAG troubles

João Paulo P Tonelli jtonelli at ic.uff.br
Thu Jan 14 22:54:38 CET 2010


Hi,
I would like to apologize for the lacking of provided information and the
missing of a reduced example. Next time I shall provide as much info as I
can in order to help you helping me.
By the way, I would also like to thank you for the tips.
I partially solved the problem by forcing the serialization of the
independent tasks, that is, adding dependencies among them, just like you
said.

2010/1/14 Frédéric Suter <frederic.suter at cc.in2p3.fr>

> Hi,
>
> Even though I do agree with Martin's remark, I have to say that I
> experienced the same kind of problem recently. I didn't found the SG
> cause of the problem, just a way to correct the problem in my code.
>
> My guess is that the chain task dependencies may be broken at some
> place. In this case, the SD_simulate function stops when there no more
> action (execution or removal of a dependency) to do. You can try to
> create two  zero costs tasks (a source and a sink), create dependencies
> between these tasks and yours and see some tasks are still not simulated.
>
> One thing you also have to be aware of is that two independent tasks
> schedule sequentially on the same resource will be executed concurrently
> by SD_simulate (as there is no dependency between them). For instance if
> task A is schedule from t=0 to t=10 on host H and task B is scheduled on
> H from t=10 to t=15, with A and B two independent tasks, the results
> will be different with SD_simulate: A and B will both start at t=0 and
> share the processing power of H. So A will will finish at t=15 and B at
> t=10. The solution is to add a new dependency between A and B before
> calling SD_Simulate.
>
> It may not be the source of your problem, but to help you more, a
> reduced example is needed.
>
> Cheers
>
> Fred
>
>
> Martin Quinson a écrit :
> > Hello Joao,
> >
> > you're asking a hard question. We of course are willing to help you
> > using the tool, but we don't have the time to debug the code of every
> > user, unfortunately. What would really help would be if you could come
> > up with a reduced example with this example. The smaller and simpler you
> > make it, the easier it is for us to track down the issue and solve it.
> > If you manage to do so, I guess that we can track the issue very
> > quickly.
> >
> > We need you to help us helping you ;)
> > Mt.
> >
> > Le mercredi 13 janvier 2010 à 12:08 -0200, João Paulo P Tonelli a
> > écrit :
> >
> >> Hello,
> >> I have developed a scheduler of DAG applications using SimDAG.
> >> Now, I am trying to use it for scheduling an application of 280 tasks
> >> on 4 hosts, but the simulation finishes without executing all tasks.
> >> I have checked whether all tasks were correctly scheduled, and they
> >> were (I saw the state of each task before the "SD_simulate()" call).
> >>
> >> I have noticed that after the simulation the tasks which were not
> >> executed either remain in  the SD_SCHEDULED state or were in the
> >> SD_IN_FIFO state.
> >> These tasks which remain in the SD_SCHEDULED state were not executed
> >> because they depend indirectly on those in SD_IN_FIFO state.
> >>
> >> I do not know what to do.
> >> Could someone help me?
> >>
> >>
> >> Regards,
> >> João Paulo Pereira Tonelli.
> >> _______________________________________________
> >> Simgrid-user mailing list
> >> Simgrid-user at lists.gforge.inria.fr
> >> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/simgrid-user
> >>
> >
> > -- I don't suffer from Insanity, I enjoy every minute of it...
> >
> >
> > _______________________________________________
> > Simgrid-user mailing list
> > Simgrid-user at lists.gforge.inria.fr
> > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/simgrid-user
>
>
> --
> Quand ça change, ça change. Faut jamais se laisser démonter !
>                                                Maître Folace
>
>
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>



-- 
Regards,
João Paulo Pereira Tonelli.
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