Dear Rogere and Rene, I'm using root 3.03.04 on a Linux Red Hat 7.2 2.00GHz CPU, and about Roger's problem I had exactly the opposite situation: I was performing some speed tests on a code reading a tree with TCloneArrays and TRefArrays and when turning on only the branches I'm interested in, the execution is faster. Cheers Davide Grandi On Fri, 27 Sep 2002, Rene Brun wrote: > Hi Roger, > > Could you move to version 3.03/09 and tell me if this symptom persists? > If it does, please send me the result of > tree.Print(); > for your old and new Trees > > Rene Brun > > On Fri, 27 Sep 2002, Roger Moore wrote: > > > Converting some analysis code from using a ROOT-tuple to using a ROOT Tree > > (i.e. from individual variables in arrays to real objects) I've noted some > > very strange behaviour with the readout speed. > > > > With the old ROOT-tuple I could vastly increase the speed of the code by > > turning off all branches and then just turning back on the branches that I > > was interested in looking at. > > > > However with the shift to the ROOT-Tree whose branches consist of > > TClonesArray the exact reverse is true! When I turn off all the branches > > except the one I am interested in the GetEntry() method of the tree takes > > 50-60ms to execute. However when I to not turn the branches off the time > > taken for GetEntry() drops to ~3ms/event. > > > > Does anyone understand what is going on here? I don't see how not > > unpacking a branch can possibly slow the code down! > > > > I'm using ROOT 3.03/07 and in both cases I only do SetBranchAddress (to a > > TClonesArray) for the branches I am interested in reading out. > > > > Roger > > > > ********************************************************************** $ Davide Grandi % $ INFN Milano e-mail Davide.Grandi@mib.infn.it % $ P.zza delle Scienze 3 phone +39 02 6448 2306 % $ 20126 MILANO fax +39 02 6448 2367 % $ ITALY % $ % $ at CERN e-mail Davide.Grandi@cern.ch % $ CH-1211 Geneve CH phone +41 22 767 9403 % $ Bldg. 506 room R018 % $ or phone +41 22 767 7560 % $ Bldg. 576 room R002 % &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
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