Alpgen Time and Size Studies

Goal

To measure the time and size performance of ALPGEN runs (grid production, event production) in a typical CMS T2 farm, like SPRACE.

Modus Operandi

IMPORTANT NOTE: do everything in a subdirectory of /hdacs, so that you have more working space and the WNs can see that space.

1. Setup a CMSSW area: cmsrel CMSSW_2_2_9; cd CMSSW_2_2_9/src; cmsenv
2. Use whatever method to be able to CVS code from CERN.
3. Get the ALPGEN grids: cvs co -r CMSSW_2_2_9 GeneratorInterface/AlpgenInterface
4. Setup CONDOR: . /OSG/setup.sh
5. Use the script to submit ALPGEN jobs to SPRACE

The script takes three arguments: the config file for ALPGEN, the name of the ALPGEN executable you want to run, and the name of the grid. It is the user's task to make sure all of those are coherent among themselves! For instance, if you want to run ttbar+4 jets, at 40 GeV threshold, starting from an already existing grid, you should use

python sprace_ALPGEN_submit.py input /OSG_app/app/cmssoft/cms/slc4_ia32_gcc345/external/alpgen/213-cms2/bin/2Qgen GeneratorInterface/AlpgenInterface/data/ttbar4j_40GeV.grid2

where input is of the form

1          ! generation mode
ttbar4j_40 ! string labeling the output files
0          ! start with: 0=new grid, 1=previous warmup grid, 2=previous generation grid
0 0        ! N(events)/iteration and N(iter's) for initial grid optimiz. Use 0 0 if starting from existing grid
50000000   ! number evts to generate
*** The above 5 lines provide mandatory inputs for all processes
*** (Comment lines are introduced by the three asteriscs)
*** The lines below modify existing defaults for the hard process under study
*** For a complete list of accessible parameters and their values,
*** input 'print 1' (to display on the screen) or 'print 2' to write to file
njets 4
ebeam 5000
ih2 1
ickkw 1
ptjmin 40
etajmax 5
drjmin 0.7
mt 175
ihvy 6
itdecmode 7

Tasks

• Check running times and event sizes for ttbar+1,3,5 jets at 40 GeV threshold, starting from already-existing grids.
• (more to be added later).

Tools

• Script to submit jobs to condor in SPRACE: sprace_ALPGEN_submit.py.txt

• Standard location of ALPGEN executables (from CMSSW): $CMS_PATH/slc4_ia32_gcc345/external/alpgen

(there are many subdirectories with different versions, pick the latest one).

Some Results

For reference, these jobs were processed in hardware configuration, using condor 7.0.3 as batch scheduler and Scientific Linux 4.6

events	average time (s)	standard deviation	size(b)
1000	0.000	0.000	1653
2000	0.000	0.000	3021
5000	0.000	0.000	5757
10000	0.667	0.943	6099
20000	6.667	1.247	7125
50000	20.667	2.494	9975
100000	43.667	2.055	15333
200000	96.333	3.399	21090
500000	248.667	2.867	29412
1000000	498.667	3.301	36765
2000000	1013.667	1.687	47652
5000000	2562.000	33.978	69711
10000000	5095.750	37.456	90288
20000000	10149.250	56.167	121866
50000000	25425.750	192.689	195567

-- ThiagoTomei - 19 May 2009