[ROOT] drawing speed problem with release 3/05 of ROOT ?

From: Damir Buskulic (buskulic@lapp.in2p3.fr)
Date: Fri Jul 11 2003 - 18:39:20 MEST 

Hi,

There seems to be a drawing speed problem in the version 3/05.04 that 
we use for online display. The small macro attached gives the following 
results :

Under OSF1/v5 (alpha XP1000 667 MHz):
root/v3/05.04:  Real Time = 12.25 seconds  Cpu Time = 6.40 seconds
root/v3/03.08:  Real Time =  8.47 seconds  Cpu Time = 3.52 seconds

Under Linux/RedHat v7.1 (PC i686 1.8 GHz):
root/v3/05.04:  Real Time = 14.40 seconds  Cpu Time = 5.06 seconds
root/v3/03.08:  Real Time = 10.13 seconds  Cpu Time = 3.36 seconds

Does anyone see this ? Were there changes in the low level layers of 
ROOT or in TH painter that could explain this ? On some of our programs 
we saw a speed decrease of a factor 4 but this is much more difficult 
to characterize simply. So here is the program :

______________________________________________________________
#include "TPad.h"
#include "TBenchmark.h"
#include "TH1.h"

void test_speed()
{
   gBenchmark->Reset();
   gBenchmark->Start("testspeed");
   TH1F* h = new TH1F("h","test_speed",20000,0,1);
   h->FillRandom("pol1",10000);
   for (int i=0;i<100;i++) {
      h->Draw();
      gPad->Update();
   }
   gBenchmark->Show("testspeed");
}
______________________________________________________________

By the way, the difference is seen in interpreted as well as compiled 
mode.

We would be grateful if anybody can help

Cheers

Damir

====================================
Damir Buskulic,  Universite de Savoie/LAPP
Chemin de Bellevue, B.P. 110, F-74941 Annecy-le-Vieux Cedex, FRANCE
Tel : +33 (0)450091600
e-mail: buskulic@lapp.in2p3.fr
====================================

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