diff --git a/src/io/libsvm_parser.h b/src/io/libsvm_parser.h
index 6579d80e3cc0..d9712c1f1a51 100644
--- a/src/io/libsvm_parser.h
+++ b/src/io/libsvm_parser.h
@@ -47,7 +47,7 @@ class LibSVMPageFactory  {
     int maxthread;
     #pragma omp parallel
     {
-      maxthread = omp_get_num_threads();
+      maxthread = omp_get_num_procs();
     }
     maxthread = std::max(maxthread / 2, 1);
     nthread_ = std::min(maxthread, nthread);
diff --git a/src/io/page_dmatrix-inl.hpp b/src/io/page_dmatrix-inl.hpp
index 9cc41fa5fc64..80bd080a3e81 100644
--- a/src/io/page_dmatrix-inl.hpp
+++ b/src/io/page_dmatrix-inl.hpp
@@ -20,7 +20,7 @@ namespace io {
 class ThreadRowPageIterator: public utils::IIterator<RowBatch> {
  public:
   ThreadRowPageIterator(void) {
-    itr.SetParam("buffer_size", "2");
+    itr.SetParam("buffer_size", "4");
     page_ = NULL;
     base_rowid_ = 0;
   }
@@ -109,7 +109,7 @@ class DMatrixPageBase : public DataMatrix {
     std::string fname = fname_;
     int tmagic;
     utils::Check(fi.Read(&tmagic, sizeof(tmagic)) != 0, "invalid input file format");
-    utils::Check(tmagic == magic, "invalid format,magic number mismatch");
+    this->CheckMagic(tmagic);
     this->info.LoadBinary(fi);
     // load in the row data file
     fname += ".row.blob";
@@ -203,6 +203,7 @@ class DMatrixPageBase : public DataMatrix {
 
  protected:
   virtual void set_cache_file(const std::string &cache_file)  = 0;
+  virtual void CheckMagic(int tmagic)  = 0;
   /*! \brief row iterator */
   ThreadRowPageIterator *iter_;
 };
@@ -221,6 +222,11 @@ class DMatrixPage : public DMatrixPageBase<0xffffab02> {
   virtual void set_cache_file(const std::string &cache_file) {
     fmat_->set_cache_file(cache_file);
   }
+  virtual void CheckMagic(int tmagic) {
+    utils::Check(tmagic == DMatrixPageBase<0xffffab02>::kMagic ||
+                 tmagic == DMatrixPageBase<0xffffab03>::kMagic,
+                 "invalid format,magic number mismatch");
+  }
   /*! \brief the real fmatrix */
   FMatrixPage *fmat_;
 };
@@ -238,7 +244,12 @@ class DMatrixHalfRAM : public DMatrixPageBase<0xffffab03> {
   virtual IFMatrix *fmat(void) const {
     return fmat_;
   }
-  virtual void set_cache_file(const std::string &cache_file) {
+  virtual void set_cache_file(const std::string &cache_file) {    
+  }
+  virtual void CheckMagic(int tmagic) {
+    utils::Check(tmagic == DMatrixPageBase<0xffffab02>::kMagic ||
+                 tmagic == DMatrixPageBase<0xffffab03>::kMagic,
+                 "invalid format,magic number mismatch");   
   }
   /*! \brief the real fmatrix */
   IFMatrix *fmat_;
diff --git a/src/io/page_fmatrix-inl.hpp b/src/io/page_fmatrix-inl.hpp
index 0883998f4332..58038a87403e 100644
--- a/src/io/page_fmatrix-inl.hpp
+++ b/src/io/page_fmatrix-inl.hpp
@@ -52,6 +52,124 @@ class ThreadColPageIterator: public utils::IIterator<ColBatch> {
   std::vector<SparseBatch::Inst> col_data_;
   utils::ThreadBuffer<SparsePage*, SparsePageFactory> itr;
 };
+
+struct ColConvertFactory {
+  inline bool Init(void) {
+    return true;
+  }
+  inline void Setup(float pkeep,
+                    size_t num_col,
+                    utils::IIterator<RowBatch> *iter,
+                    std::vector<bst_uint> *buffered_rowset,
+                    const std::vector<bool> *enabled) {
+    pkeep_ = pkeep;
+    num_col_ = num_col;
+    iter_ = iter;
+    buffered_rowset_ = buffered_rowset;
+    enabled_ = enabled;
+  }
+  inline SparsePage *Create(void) {
+    return new SparsePage();
+  }
+  inline void FreeSpace(SparsePage *a) {
+    delete a;
+  }
+  inline void SetParam(const char *name, const char *val) {}
+  inline bool LoadNext(SparsePage *val) {
+    tmp_.Clear();
+    size_t btop = buffered_rowset_->size();
+    while (iter_->Next()) {
+      const RowBatch &batch = iter_->Value();
+      for (size_t i = 0; i < batch.size; ++i) {
+        bst_uint ridx = static_cast<bst_uint>(batch.base_rowid + i);
+        if (pkeep_ == 1.0f || random::SampleBinary(pkeep_)) {
+          buffered_rowset_->push_back(ridx);
+          tmp_.Push(batch[i]);
+        }
+      }
+      if (tmp_.MemCostBytes() >= kPageSize) {
+        this->MakeColPage(tmp_, BeginPtr(*buffered_rowset_) + btop,
+                          *enabled_, val);
+        return true;
+      }
+    }
+    if (tmp_.Size() != 0){
+        this->MakeColPage(tmp_, BeginPtr(*buffered_rowset_) + btop,
+                          *enabled_, val);
+        return true;
+    } else {
+      return false;
+    }
+  }
+  inline void Destroy(void) {}  
+  inline void BeforeFirst(void) {}
+  inline void MakeColPage(const SparsePage &prow,
+                          const bst_uint *ridx,
+                          const std::vector<bool> &enabled,
+                          SparsePage *pcol) {
+    pcol->Clear();
+    int nthread;
+    #pragma omp parallel
+    {
+      nthread = omp_get_num_threads();
+      int max_nthread = std::max(omp_get_num_procs() / 2 - 4, 1); 
+      if (nthread > max_nthread) {
+        nthread = max_nthread;
+      }
+    }
+    pcol->Clear();
+    utils::ParallelGroupBuilder<SparseBatch::Entry>
+        builder(&pcol->offset, &pcol->data);
+    builder.InitBudget(num_col_, nthread);
+    bst_omp_uint ndata = static_cast<bst_uint>(prow.Size());
+    #pragma omp parallel for schedule(static) num_threads(nthread)
+    for (bst_omp_uint i = 0; i < ndata; ++i) {
+      int tid = omp_get_thread_num();
+      for (size_t j = prow.offset[i]; j < prow.offset[i+1]; ++j) {
+        const SparseBatch::Entry &e = prow.data[j];
+        if (enabled[e.index]) { 
+          builder.AddBudget(e.index, tid);
+        }
+      }    
+    }
+    builder.InitStorage();
+    #pragma omp parallel for schedule(static) num_threads(nthread)
+    for (bst_omp_uint i = 0; i < ndata; ++i) {
+      int tid = omp_get_thread_num();
+      for (size_t j = prow.offset[i]; j < prow.offset[i+1]; ++j) {
+        const SparseBatch::Entry &e = prow.data[j];
+        builder.Push(e.index,
+                     SparseBatch::Entry(ridx[i], e.fvalue),
+                     tid);
+      }
+    }
+    utils::Assert(pcol->Size() == num_col_, "inconsistent col data");
+    // sort columns
+    bst_omp_uint ncol = static_cast<bst_omp_uint>(pcol->Size());
+    #pragma omp parallel for schedule(dynamic, 1) num_threads(nthread)
+    for (bst_omp_uint i = 0; i < ncol; ++i) {
+      if (pcol->offset[i] < pcol->offset[i + 1]) {
+        std::sort(BeginPtr(pcol->data) + pcol->offset[i],
+                  BeginPtr(pcol->data) + pcol->offset[i + 1],
+                  SparseBatch::Entry::CmpValue);
+      }
+    }
+  }
+  // probability of keep
+  float pkeep_;
+  // number of columns
+  size_t num_col_;
+  // row batch iterator
+  utils::IIterator<RowBatch> *iter_;
+  // buffered rowset
+  std::vector<bst_uint> *buffered_rowset_;
+  // enabled marks
+  const std::vector<bool> *enabled_;  
+  // internal temp cache
+  SparsePage tmp_;
+  /*! \brief page size 256 M */
+  static const size_t kPageSize = 256 << 20UL;
+};
 /*!
  * \brief sparse matrix that support column access, CSC
  */
@@ -165,44 +283,34 @@ class FMatrixPage : public IFMatrix {
    * \param pkeep probability to keep a row
    */
   inline void InitColData(const std::vector<bool> &enabled, float pkeep) {
-    SparsePage prow, pcol;
-    size_t btop = 0;
     // clear rowset
     buffered_rowset_.clear();
     col_size_.resize(info.num_col());
     std::fill(col_size_.begin(), col_size_.end(), 0);
     utils::FileStream fo;
     fo = utils::FileStream(utils::FopenCheck(col_data_name_.c_str(), "wb"));
-    size_t bytes_write = 0;
-    double tstart = rabit::utils::GetTime();
-    // start working
     iter_->BeforeFirst();
-    while (iter_->Next()) {
-      const RowBatch &batch = iter_->Value();
-      for (size_t i = 0; i < batch.size; ++i) {
-        bst_uint ridx = static_cast<bst_uint>(batch.base_rowid + i);
-        if (pkeep == 1.0f || random::SampleBinary(pkeep)) {
-          buffered_rowset_.push_back(ridx);
-          prow.Push(batch[i]);
-          if (prow.MemCostBytes() >= kPageSize) {
-            bytes_write += prow.MemCostBytes();
-            this->PushColPage(prow, BeginPtr(buffered_rowset_) + btop,
-                              enabled, &pcol, &fo);
-            btop += prow.Size();
-            prow.Clear();
-            
-            double tdiff = rabit::utils::GetTime() - tstart;
-            utils::Printf("Writting to %s in %g MB/s, %lu MB written\n",
-                          col_data_name_.c_str(),
-                          (bytes_write >> 20UL) / tdiff,
-                          (bytes_write >> 20UL));
-          }
-        }
+    double tstart = rabit::utils::GetTime();
+    size_t bytes_write = 0;
+    utils::ThreadBuffer<SparsePage*, ColConvertFactory> citer;
+    citer.SetParam("buffer_size", "2");
+    citer.get_factory().Setup(pkeep, info.num_col(),
+                              iter_, &buffered_rowset_, &enabled);
+    citer.Init();
+    SparsePage *pcol;
+    while (citer.Next(pcol)) {
+      for (size_t i = 0; i < pcol->Size(); ++i) {
+        col_size_[i] += pcol->offset[i + 1] - pcol->offset[i];        
       }
-    }
-    if (prow.Size() != 0) {
-      this->PushColPage(prow, BeginPtr(buffered_rowset_) + btop,
-                        enabled, &pcol, &fo);
+      pcol->Save(&fo);
+      size_t spage = pcol->MemCostBytes();
+      bytes_write += spage;
+      double tnow = rabit::utils::GetTime();      
+      double tdiff = tnow - tstart;
+      utils::Printf("Writting to %s in %g MB/s, %lu MB written current speed:%g MB/s\n",
+                    col_data_name_.c_str(),
+                    (bytes_write >> 20UL) / tdiff,
+                    (bytes_write >> 20UL));
     }
     fo.Close();
     num_buffered_row_ = buffered_rowset_.size();
@@ -210,56 +318,6 @@ class FMatrixPage : public IFMatrix {
     this->SaveMeta(&fo);
     fo.Close();
   }
-  inline void PushColPage(const SparsePage &prow,
-                          const bst_uint *ridx,
-                          const std::vector<bool> &enabled,
-                          SparsePage *pcol,
-                          utils::IStream *fo) {
-    pcol->Clear();
-    int nthread;
-    #pragma omp parallel
-    {
-      nthread = omp_get_num_threads();
-    }
-    pcol->Clear();
-    utils::ParallelGroupBuilder<SparseBatch::Entry>
-        builder(&pcol->offset, &pcol->data);
-    builder.InitBudget(info.num_col(), nthread);
-    bst_omp_uint ndata = static_cast<bst_uint>(prow.Size());
-    #pragma omp parallel for schedule(static)
-    for (bst_omp_uint i = 0; i < ndata; ++i) {
-      int tid = omp_get_thread_num();
-      for (size_t j = prow.offset[i]; j < prow.offset[i+1]; ++j) {
-        const SparseBatch::Entry &e = prow.data[j];
-        if (enabled[e.index]) { 
-          builder.AddBudget(e.index, tid);
-        }
-      }    
-    }
-    builder.InitStorage();
-    #pragma omp parallel for schedule(static)
-    for (bst_omp_uint i = 0; i < ndata; ++i) {
-      int tid = omp_get_thread_num();
-      for (size_t j = prow.offset[i]; j < prow.offset[i+1]; ++j) {
-        const SparseBatch::Entry &e = prow.data[j];
-        builder.Push(e.index,
-                     SparseBatch::Entry(ridx[i], e.fvalue),
-                     tid);
-      }
-    }
-    utils::Assert(pcol->Size() == info.num_col(), "inconsistent col data");
-    // sort columns
-    bst_omp_uint ncol = static_cast<bst_omp_uint>(pcol->Size());
-    #pragma omp parallel for schedule(dynamic, 1)
-    for (bst_omp_uint i = 0; i < ncol; ++i) {
-      if (pcol->offset[i] < pcol->offset[i + 1]) {
-        std::sort(BeginPtr(pcol->data) + pcol->offset[i],
-                  BeginPtr(pcol->data) + pcol->offset[i + 1], Entry::CmpValue);
-      }
-      col_size_[i] += pcol->offset[i + 1] - pcol->offset[i];
-    }    
-    pcol->Save(fo);  
-  }
 
  private:
   /*! \brief page size 256 M */