Comparison between Pass7 (P202) and Pass8 (P300) reconstruction

A comparison has been made between Pass7 and Pass8 reconstruction based on a single run (the 2nd run in the Fermi science data). There are three primary findings: timing, recon file size, and memory usage.

Details

P202 GR

17-35-24

P300 GR

20-08-12

Run

239559565

2008-08-04 16:19:24 UTC

#Evts

2,010,995

Reconstruction processing time (Gleam)

Spreadsheet of job execution details:

https://docs.google.com/spreadsheet/ccc?key=0AveNVqKMtmVEdHJfbUNLMGs0S0NBcV9iaVhvMl9mdHc&usp=sharing

P202 (events/s)

P300 (events/s)

P202\:P300 ratio

6.71

2.45

2.74

RECON File size

P202 (kB/event)

P300 (kB/event)

P300\:P202

14.67

37.27

2.54

Also see spreadsheet for exact numerology.

Memory footprint

Max memory reported by LSF

P202 (MB)

P300 (MB)

1800 (after 100,000 evts)

1730 (after 20,000 evts – but with memory leak)

Notes:

  1. P202 max mem after processing ~96,000 events
  2. P300 max mem after processing only ~20,000 events
  3. P300 starts at ~600MB and has a mem leak of ~55kB/event, which limits clump size. At ~60k-80k events, memory consumption has grown to make crashes inevitable, e.g., 
    terminate called after throwing an instance of 'std::bad_alloc'
  what():  St9bad_alloc
sh: line 1: 25973 Aborted                 Gleam
    The exact time of a crash is unpredictable as it depends on the total memory resources and usage on a particular machine.
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