Benchmark test for Objectivity/DB performance
This note summarises the preliminary results obtained by integrating
the Objectivity/DB Management System
in Geant4. The benchmark is referring to a simulation based on the
honey-comb calorimeter detector defined for the CERN School of Computing
1994 exercises on GEANT. It produces and stores calorimeter or tracker hits
as collection of ordered values or pointers in DB containers.
Events produced consist of two collections of hits ("even" and "odd", 17
and 19 elements for Calorimeter-hits, 1700 and 1900 elements for Tracker-
hits respectively). The test will generate 10 events of 100 "geantinos" each in total.
The time needed for generate persistent hits in the DB, is compared to
that needed for the "transient" case, that's when the DB is not used.
The results demonstrate that there's no significant overhead in performance
between the transient version and the persistent Objectivity-based one.
It has also been measured that the overhead in storage-size is not
significant, as well as the time spent in accessing the DB (as it can be
observed from the timings of the Tracker-hits vs Calorimeter-hits).
The test has been made in collaboration with the
RD45 team.
Timings are expressed in seconds (user-time and real-time). The tests
have been run on an IBM-AIX machine (cernsp) ...
-------------------------------------------------------------
| Calorimeter | Tracker
Collection |------------------------|------------------------
| Transient | Persistent | Transient | Persistent
-----------|-----------|------------|-----------|------------
Pointer | u=7.96 | u=9.63 | u=8.80 | u=13.09
ordered | r=12.2 | r=14.22 | r=9.63 | r=26.33
-----------|-----------|------------|-----------|------------
Value | u=8.66 | u=8.37 | u=9.66 | u=8.89
ordered | r=10.96 | r=15.87 | r=11.28 | r=14.41
-------------------------------------------------------------
Thu Dec 12 1996 GC