[Swift-user] Tuning parameters of coaster execution

[Andriy Fedorov]

On Tue, Oct 20, 2009 at 11:55, Mihael Hategan <hategan at mcs.anl.gov> wrote:
> You need a more recent version of the code.
>

Mihael, I actually updated svn for both cog and swift yesterday prior
to running the tests. Here's what swift reports I have right now:

Swift svn swift-r3170 cog-r2529



> A few weeks ago the "parallelism" option was added. By default it's set
> to try to allocate as many nodes as there are jobs (parallelism=0.0),
> whereas the behavior you see would have parallelism=1.0. I should change
> the way the numbers are specified. It's not exactly intuitive unless you
> look at how it works.
>
> Anyway, it boils down to the notion of job size and block size. The
> block size is defined as workers*bwalltime^parallelism, while the job
> size is jwalltime^parallelism. At any given time you can fit roughly
> workers*bwalltime^parallelism/jwalltime^parallelism jobs in a block.
>
> You can see that with parallelism=0, that reduces to
> workers/count(jobs).
>
> Conversely, with parallelism=1 the jobs size is jwalltime and if your
> block had bwalltime you could fit workers*bwalltime/jwalltime jobs in
> it.
>
> At the same time, bwalltime is controlled by the overallocation factors.
> Once the block walltime is decided, the width (number of workers) is
> picked based on the job sizes that need to be fit (according to the
> above scheme).
>
> Anyway, to sum it up, use a more recent version.
>
>