benchmarking TClonesArray vs STL vector

From: Pasha Murat (murat@cdfsga.fnal.gov)
Date: Wed Dec 16 1998 - 02:51:47 MET


Hi Rooters, 

	I finally found some time to benchmark ROOT TClonesArray against STL vectors.
Briefly the results: for HEP-like applications (loop over the events) TClonesArray seems 
to be more efficient than STL vectors even if no sorting of the objects is involved. 
On SGI IRIX6.2 (R10000) the test code using TClonesArray runs about 50% faster than 
similar code using STL vector of objects and about 3 times faster than the code using STL 
vector of pointers.

	The results on Linux are similar, those are preliminary though.

While satisfied, I do not quite understand why TClonesArray performed in this test 
faster than vector. It is also clear that when the sorting will be involved the 
difference should become even more striking. May be there is something in my code 
I don't see?

See the description of the test conditions and the complete source code of the program 
executed (including the Makefile) at URL

http://www-cdf.fnal.gov/upgrades/computing/projects/run2mc/run2mc.html

(see news from Dec 14, this includes a little bit of advertisement of new CDF MC web page), 

a direct pointer is:

http://www-cdf.fnal.gov/upgrades/computing/projects/run2mc/minutes/1998_12_10/TClonesArray_vs_vector.html

			I appreciate any comments, regards, pasha.



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