Using only RootTree patch:

Index: src/IOPool/Input/src/RootFile.cc
===================================================================
RCS file: /cvs_server/repositories/CMSSW/CMSSW/IOPool/Input/src/RootFile.cc,v
retrieving revision 1.195.2.2
diff -u -r1.195.2.2 RootFile.cc
--- src/IOPool/Input/src/RootFile.cc    3 Dec 2009 20:52:00 -0000       1.195.2.2
+++ src/IOPool/Input/src/RootFile.cc    20 Jan 2010 01:44:31 -0000
@@ -850,6 +850,9 @@
     while(fileIndexIter_ != fileIndexEnd_ && fileIndexIter_->getEntryType() != FileIndex::kEvent) {
       ++fileIndexIter_;
     }
+
+    eventTree_.fHasTrained_ = kFALSE;
+
     return (fileIndexIter_ == fileIndexEnd_);
   }

Index: src/IOPool/Input/src/RootTree.cc
===================================================================
RCS file: /cvs_server/repositories/CMSSW/CMSSW/IOPool/Input/src/RootTree.cc,v
retrieving revision 1.50
diff -u -r1.50 RootTree.cc
--- src/IOPool/Input/src/RootTree.cc    20 Aug 2009 15:31:44 -0000      1.50
+++ src/IOPool/Input/src/RootTree.cc    20 Jan 2010 01:44:31 -0000
@@ -12,6 +12,7 @@
 #include "TTreeCache.h"

 #include <iostream>
+using namespace std;

 namespace edm {
   namespace {
@@ -43,6 +44,7 @@
     entryNumber_(-1),
     branchNames_(),
     branches_(new BranchMap),
+    fHasTrained_(kFALSE),
     productStatuses_(), // backward compatibility
     pProductStatuses_(&productStatuses_), // backward compatibility
     infoTree_(dynamic_cast<TTree *>(filePtr_.get() != 0 ? filePtr->Get(BranchTypeToInfoTreeName(branchType).c_str()) : 0)), // backward compatibility
@@ -123,6 +125,7 @@
   RootTree::setCacheSize(unsigned int cacheSize) {
     tree_->SetCacheSize(static_cast<Long64_t>(cacheSize));
     treeCache_ = dynamic_cast<TTreeCache *>(filePtr_->GetCacheRead());
+    cout << "setCacheSize " << cacheSize << ", TTreeCache " << treeCache_ << endl;
     filePtr_->SetCacheRead(0);
   }

@@ -134,18 +137,11 @@
   void
   RootTree::setEntryNumber(EntryNumber theEntryNumber) {
     filePtr_->SetCacheRead(treeCache_);
-    if (treeCache_) {
-      assert(treeCache_->GetOwner() == tree_);
-      if (theEntryNumber >= 0 && treeCache_->IsLearning()) {
-       treeCache_->SetLearnEntries(1);
-       treeCache_->SetEntryRange(0, tree_->GetEntries());
-        for (BranchMap::const_iterator i = branches_->begin(), e = branches_->end(); i != e; ++i) {
-         if (i->second.productBranch_) {
-           treeCache_->AddBranch(i->second.productBranch_, kTRUE);
-         }
-       }
-        treeCache_->StopLearningPhase();
-      }
+    if (treeCache_ && !fHasTrained_ && theEntryNumber >= 0) {
+        cout << "Training started on event " << theEntryNumber << endl;
+        treeCache_->SetLearnEntries(20);
+        treeCache_->SetEntryRange(theEntryNumber, tree_->GetEntries());
+        fHasTrained_ = kTRUE;
     }
     entryNumber_ = theEntryNumber;
     tree_->LoadTree(theEntryNumber);
@@ -160,6 +156,7 @@
     auxBranch_  = branchEntryInfoBranch_ = statusBranch_ = 0;
     tree_ = metaTree_ = infoTree_ = 0;
     treeCache_ = 0;
+    fHasTrained_ = kFALSE;
     filePtr_.reset();
   }

Index: src/IOPool/Input/src/RootTree.h
===================================================================
RCS file: /cvs_server/repositories/CMSSW/CMSSW/IOPool/Input/src/RootTree.h,v
retrieving revision 1.39
diff -u -r1.39 RootTree.h
--- src/IOPool/Input/src/RootTree.h     1 Sep 2009 23:31:59 -0000       1.39
+++ src/IOPool/Input/src/RootTree.h     20 Jan 2010 01:44:31 -0000
@@ -69,6 +69,7 @@
     } // backward compatibility

     TBranch *const branchEntryInfoBranch() const {return branchEntryInfoBranch_;}
+    bool fHasTrained_;

   private:
     boost::shared_ptr<TFile> filePtr_;
cvs diff: Diffing src/IOPool/Input/test

• CSCS-PAT1-QCD_Pt80Summer09.MC_31X_V3_AODSIM.v1AODSIM-10000-CMSSW_3_3_2-201001041019.root: CSCS-PAT1-QCD_Pt80Summer09.MC_31X_V3_AODSIM.v1AODSIM-10000-CMSSW_3_3_2-201001041019.root

• CSCS-PAT1-QCD_Pt80Summer09-Overview.jpg:
  

All patches

 /usr/bin/curl -k https://twiki.cern.ch/twiki/pub/Sandbox/CmsIOWork/ttreecache_rollup.patch | patch -p 0
 /usr/bin/curl https://twiki.cern.ch/twiki/pub/Sandbox/CmsIOWork/read_coalesce.patch | patch -p0

CSCS

KNU

--+++ Nebraska

Pisa

Wisconsin