[SCore-users] Gang scheduling details

[John Uhlmann]

You'll have to wait for the official response to confirm this, but my
interpretation and is that the scheduling on the time-sharing queues in
SCore is loosely based on the Distributed Hierarchical Control gang
scheduling algorithm from Feitelson.  I say loosely since SCore does not
seem to define the logical hierarchy of controllers that Feitelson
proposes and also had to make some allowances for use on a real
machine.  Basically, jobs are allocated in a buddy fashion if possible
but will be squeezed in anyway if this isn't possible (i.e. resources
are low).  A centralised controller then coordinates the gang scheduling
of the processes (where gang scheduling is the simultaneous
running/preemption of processes within the same job).

The short answer - buddy based gang scheduling.

For the definitive answer, look in and around
/opt/score/score-src/scored/scored/tss.cc (I think)
Also I believe there are some papers by Hori et al on the
implementation.  And for details of the buddy allocation scheme start
with Feitelson.

John Uhlmann

Shreenivasa Venkataramaiah wrote:
> 
> Hello,
> 
> I wanted to know the exact details about the implementation of gang
> scheduling in Score. I am looking for a gang scheduing system which
> works in this fashion:
>     - imagine a parallel application to be scheduled on 'n' nodes as 'n'
> processes
>     - the scheduling must be such that when this application is run such
> that it has to share the nodes with other jobs, then all the processes
> of this application must be scheduled on all the nodes at the same time.
> Similarly all the processes must be preempted from all the nodes at the
> same time (i.e. if there are still in the running state).
>     - I know there are a lot of impelementation issues to be dealt with
> here, but I wanted to know whether something similar is done in SCore
> and if yes, what are the details of the implementation.
> 
> thanks,
> shreeni.
> 
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