Hi , I recently changed my code to use Eventlists before looping over a TChain. First I create a Eventlist via TChain::Draw(">>elis","selction") Second I read from the Tree only entries which are in the eventlist via for (Int_t i =0; i< NSelectedEvents; i++){ GetEvent(MyList->GetEntry(i)); } The list contains approx 10 percent of the events in the TChain. (20 Mio) It seems that the correct events are extracted from the tree, but the performace does not improve. The running process uses approx only 18 - 20 percent of the availible CPU time. I guess root tries to find the entry but since ist is not the next in the tree but somwhere else it has to access the disk for each GetEntry(). Does it help to increase the BasketBuffer Size ? Or maybe fmaxvirtual size ? Thanks Norbert -- Norbert Danneberg ETH Zurich - Institute for Particle Physics Laboratory for Nuclear Physics Phone.: +41-1-633-2034 Hoenggerberg Fax.: +41-1-633-1067 CH-8093 Zurich ETH Zurich - Institute for Particle Physics Paul Scherrer Institute Phone.: +41-56-310-3284 CH-5232 Villigen PSI Fax.: +41-56-310-4362 email: Norbert.Danneberg@psi.ch
This archive was generated by hypermail 2b29 : Tue Jan 02 2001 - 11:50:37 MET