[Beowulf] scheduler policy design
toon.knapen at fft.be
Tue Apr 24 08:30:31 EDT 2007
Tim Cutts wrote:
>> but what if you have a bi-cpu bi-core machine to which you assign 4
>> slots. Now one slot is being used by a process which performs heavy
>> IO. Suppose another process is launched that performs heavy IO. In
>> that case the latter process should wait until the first one is done
>> to avoid slowing down the efficiency of the system. Generally however,
>> clusters take only time and memory requirements into account.
> I think that varies. LSF records the current I/O of a node as one of
> its load indices, so you can request a node which is doing less than a
> certain amount of I/O. I imagine the same is true of SGE, but I
> wouldn't know.
Indeed, using SGE you could also take this into account. However if
someone submits 4 jobs, the jobs do not directly start to generate heavy
I/O. So the scheduler might think that the 4 jobs can easily coexist on
this same node. However, after a few minutes all 4 jobs start eating
disk BW and slow the node down horribly. What would your suggestion be
to solve this ?
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