Hi,
There was a thread a few months ago about drawing speed of ROOT. I'm
trying to replace PAW routines by ROOT ones in an online data display
program. The main observed difference is the drawing speed in the case
of ROOT, which is much slower than PAW. While I can understand this (a
factor of two in the best case) it is difficult to understand the
variation of drawing speed with the canvas size. Try the following macro
:
{
gBenchmark->Start("toto");
c1 = new TCanvas("c1","test",10,10,700,700);
h = new TH1F("h","h",1000,0,10);
for (int i=1;i<100;i++) {
h->Fill(gRandom->Gaus(5,1.5),1);
h->Draw();
gPad->Update();
}
gBenchmark->Show("toto");
}
on my machine this needs around 14 s real time to be completed (Alpha
XP1000).
change the size of the canvas to 50x50 (not usable, it's just for
demonstrating the effect), the real time goes down to 2.8s !
Though fons explained the speed difference between PAW and ROOT, he
stated that the drawing speed should not depend much on the canvas size.
This is true for CPU time but not for real time.
I also tested on a distant display, and the results are the same (14s
and 3s).
In our context, and if this figure cannot be changed, I don't see yet
how to use root to display in real time a set of 10 histograms or plots.
Anyone has a suggestion ? it will be welcome !
Cheers
Damir
--
=====================================================================
| Damir Buskulic | Universite de Savoie/LAPP |
| | Chemin de Bellevue, B.P. 110 |
| Tel : +33 (0)450091600 | F-74941 Annecy-le-Vieux Cedex |
| e-mail: buskulic@lapp.in2p3.fr | FRANCE |
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mailto:buskulic@lapp.in2p3.fr
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