RE: [ROOT] execution speed of compiled programs using ROOT

From: Philippe Canal (pcanal@fnal.gov)
Date: Wed Aug 13 2003 - 23:20:07 MEST 

Hi Thomas,

I can indeed reproduce the same slowdown by a factor of 2.  I suspect that
this is due to the multi-thread nature of the ROOT implementation on
Windows.  (I.e. the other thread are probably being run).  We will
check further.

Cheers,
Philippe.

-----Original Message-----
From: owner-roottalk@pcroot.cern.ch
[mailto:owner-roottalk@pcroot.cern.ch]On Behalf Of Thomas Nisius
Sent: Friday, August 08, 2003 7:28 AM
To: roottalk@pcroot.cern.ch
Subject: [ROOT] execution speed of compiled programs using ROOT


Hi,

when I compile a program that include some root objects, execution speed
drops significantly.
please see the following example:

#include <time.h>
#include <iostream>
using namespace std;

#include <TH2D.h>
#define USE_ROOT

int main(int argc, char* argv[]) {

#ifdef USE_ROOT
  TH2D *h = new TH2D("test","test",64,0,1,64,0,1);
  h->FillRandom("gaus",1000);
#endif

  double r=0;
  double time = clock(); // save the clock
  for(long int i=0; i<100000000; i++) {
    r += 0.5;
  }
  cout << r << endl;
  cout << "Duration: " << clock() - time << endl;
  return 0;
}

if in this example 'USE_ROOT' is defined the duration is nearly twice as
long as without it.
(note, that only the execution of the loop is taken into account, not the
histo filling)

I'm using Root 3.05/07 (win32gdk-version) on WinXP & Win2000
Compiler: MSVC++ 6
I link libCore.lib and libHist.lib to my Project

Any suggestions?

Kind Regards
Thomas Nisius
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