[Halld-offline] memory usage for bggen events

[Kei Moriya]

To follow up on the discussion at the Data Challenge meeting
regarding memory usage for bggen jobs, I ran over 10 runs for
each configuration of EM background level and had the cluster report
back the maximum vmem used (see attached plot).

Note that the spikes in max vmem happened most frequently for
standard EM background (the dashed lines are the average for
each EM background type, but they are influenced strongly by
the outliers), while the set with high rate and long gate time
has no large spikes.

The jobs were set up so that for each run, the original thrown hddm
file was the same for each EM background set. The RNDM variable
specified in control.in for hdgeant was always the same. Does
anybody know if the simulation of the detector hits is done
independent of the EM background, or if the EM background offsets
the random number sequence for each hit?

I also monitored the time it took for each job type to finish.
The results are
type        time (hrs)
no EM bg    1 - 1.5
standard    2 - 3.5
high rate   5 - 5.5
long gate   3 - 3.5
high rate, long gate  10 - 15

Most of the time is being spent on hdgeant. I don't know why
some jobs take 50% more time than others. The increase in
processing time is a much larger penalty than the small increase
we see in the final REST file sizes.

I've also started looking into the number of tracks and track quality,
and also photon timing information.

	Kei


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