{
  TFile *f = TFile::Open("/tmp/tarrade/user.FabienTarrade.data10_7TeV.periodF.physics_Egamma.PhysCont.AOD.t0pro04_v01.D3PD_DILEP-09-2010_1_GRL.100908171907/user.FabienTarrade.005646.AANT._00479.root");
  T = (TTree*)f->Get("physics");
 
  TTreePerfStats *ps = new TTreePerfStats("ioperf",T);
  
  Long64_t n = T->GetEntries();

  std::string name_file_histo="TEST.root";
  TFile *fout=new TFile(name_file_histo.c_str(),"recreate");
  //Imagine I put a lot of TH1 in file.root
  fout->Close();

  
  T->Draw("el_E");

  // I want to add  TTreePerfStats in my previous TEST.root
  std::string name_file_histo="TEST.root";
  TFile *fout=new TFile(name_file_histo.c_str(),"recreate");
   
  ps->Finish();
  ps->Write(); 
  fout->Write();
  fout->Close();
}