[ROOT] hsimple speed root_v3.04.02 vs root_v3.05.0x on Linux RH7.1-3

From: Andrzej Kupsc (kupsc@tsl.uu.se)
Date: Wed May 07 2003 - 11:55:30 MEST


Hej,

  We have found that some of our root based applications seems to run 
2-4 times slower with root_v3.05.04 as compared to root_v3.04.02.

In order to find the reason of decreased performance we have run standard  
root benchmarks with precompiled root versions as well as root_v3.05.04 
compiled from sources.
The comparison was done on the same computers with the only difference 
being root version used. Most dramatic difference is with 
$ROOTSYS/test/hsimple.cxx which seems to be more than 4 times slower with 
ROOT 3.05/04.
Does anyone observed similar decrease of performance with root_v3.05.04
or have hints what could be wrong?  

Andrzej Kupsc
---------------------------------------------------------------
                  The Svedberg Laboratory,
                  Uppsala University, Uppsala.
---------------------------------------------------------------



--------------------
Results of the tests
--------------------
 ROOT versions used for tests:
  root_v3.04.02.Linux.RH7.2.gcc296.tar.gz
  root_v3.05.04.Linux.RH7.3.gcc296.tar.gz
    root_v3.05.04 recompiled from sources was also tested but that make 
    no differences with root_v3.05.04.Linux.RH7.3.gcc296   	
    also we have tried root_v3.05.03 which behaves similar
  

**1** Script benchmark.C is 2x slower for hsimple and 
hsum  we run it on our 2 computers (1 and 2 processor)
with RH 7.1 (but results are similar on a computer with RH 7.3)

  computer1:  2x Pentium III
  cpu MHz         : 799.693 
  kernel : 2.4.18-27.7.xsmp
  Processing benchmark: rootmarks.C
---------------ROOT 3.04/02 benchmarks summary--------------------
hsimple   : Real Time =   0.71 seconds Cpu Time =   0.65 seconds
hsum      : Real Time =   0.31 seconds Cpu Time =   0.30 seconds
.....
---------------ROOT 3.05/04 benchmarks summary--------------------
hsimple   : Real Time =   1.32 seconds Cpu Time =   1.21 seconds
hsum      : Real Time =   0.83 seconds Cpu Time =   0.83 seconds
....

  computer2:  1x Intel(R) Pentium(R) 4 CPU 1.80GHz
  gcc version 2.96 20000731 (Red Hat Linux 7.1 2.96-98)
  Linux: 2.4.7-10

Processing benchmark: rootmarks.C
---------------ROOT 3.05/04 benchmarks summary--------------------
hsimple   : Real Time =   1.62 seconds Cpu Time =   0.89 seconds
hsum      : Real Time =   1.10 seconds Cpu Time =   0.60 seconds
....
Processing benchmark: rootmarks.C
---------------ROOT 3.04/02 benchmarks summary--------------------
hsimple   : Real Time =   0.84 seconds Cpu Time =   0.47 seconds
hsum      : Real Time =   0.42 seconds Cpu Time =   0.22 seconds
....

**2**  
Standard  $ROOTSYS/test/hsimple.cxx with standard Makefile was used.
In order to test speed the event loop in the hsimple.cxx were increased to 
1M events and TStopwatch was put at the beginning and at the end of the 
program to measure performance.

computer1:                      
  ROOT 3.05/04 
./hsimple 
Time : RT= 11.53 s  Cpu= 11.44 s
  ROOT 3.04/02 
./hsimple
Time : RT=  2.20 s  Cpu=  2.19 s

computer2:
  ROOT 3.05/04
./hsimple
Time : RT=  7.88 s  Cpu=  7.67 s
  ROOT 3.04/02
./hsimple
Time : RT=  1.87 s  Cpu=  1.84 s



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