diff --git a/include/stxxl/bits/containers/sorter.h b/include/stxxl/bits/containers/sorter.h
index 08d6fe570..f8c24876b 100644
--- a/include/stxxl/bits/containers/sorter.h
+++ b/include/stxxl/bits/containers/sorter.h
@@ -248,6 +248,20 @@ class sorter
         return m_runs_merger.empty();
     }
 
+    //! Return the number of elements in a single run of the runs_creator
+    size_t num_els_in_run() const {
+      return m_runs_creator.num_els_in_run();
+    }
+
+    //! This number of elements will be merged at one
+    size_t num_els_in_output_block() const {
+      return m_runs_merger.num_els_in_output_block();
+    }
+    //! Will the next call to operator++ block, because it needs to merge?
+    bool next_call_would_block() const {
+      return m_runs_merger.next_call_would_block();
+    }
+
     //! \}
 
     //! \name Operators
@@ -274,6 +288,14 @@ class sorter
         return *this;
     }
 
+    bool next_output_would_block() const {
+      return m_runs_merger.next_output_would_block();
+    }
+
+    size_t output_block_size() const {
+      return m_runs_merger.output_block_size();
+    }
+
     //! \}
 };
 
diff --git a/include/stxxl/bits/stream/sort_stream.h b/include/stxxl/bits/stream/sort_stream.h
index 7bb126ec1..7ea46496d 100644
--- a/include/stxxl/bits/stream/sort_stream.h
+++ b/include/stxxl/bits/stream/sort_stream.h
@@ -718,6 +718,11 @@ class runs_creator<
     {
         return m_memory_to_use;
     }
+
+    //! return number of elements in a single sort run
+    size_t num_els_in_run() const {
+      return m_el_in_run;
+    }
 };
 
 //! Input strategy for \c runs_creator class.
@@ -1342,6 +1347,12 @@ class basic_runs_merger
         return &(operator * ());
     }
 
+    bool next_output_would_block() const {
+      return m_current_ptr + 1 == m_current_end;
+    }
+
+    size_t output_block_size() const { return out_block_type::size; }
+
     //! Standard stream method.
     basic_runs_merger& operator ++ ()       // preincrement operator
     {