partition.h (__parallel_partition): Correctly initialize chunk size.

2009-11-19  Johannes Singler  <singler@kit.edu>

        * include/parallel/partition.h (__parallel_partition): Correctly
        initialize chunk size.
        (__parallel_nth_element): Respect nth_element_minimal_n.  Use
        sequential nth_element as base case, instead of sequential sort.

From-SVN: r154333

libstdc++-v3/ChangeLog

+2009-11-19  Johannes Singler  <singler@kit.edu>
+
+        * include/parallel/partition.h (__parallel_partition): Correctly
+        initialize chunk size.
+        (__parallel_nth_element): Respect nth_element_minimal_n.  Use
+        sequential nth_element as base case, instead of sequential sort.
+
 2009-11-17  Benjamin Kosnik  <bkoz@redhat.com>
 
 	* include/profile/impl/profiler.h: Remove namespace markup.

libstdc++-v3/include/parallel/partition.h

@@ -73,7 +73,7 @@ namespace __gnu_parallel
 
       bool* __reserved_left = NULL, * __reserved_right = NULL;
 
-      _DifferenceType __chunk_size;
+      _DifferenceType __chunk_size = __s.partition_chunk_size;
 
       omp_lock_t __result_lock;
       omp_init_lock(&__result_lock);
@@ -345,8 +345,9 @@ namespace __gnu_parallel
       _RAIter __split;
       _RandomNumber __rng;
 
-      _DifferenceType __minimum_length =
-	std::max<_DifferenceType>(2, _Settings::get().partition_minimal_n);
+      const _Settings& __s = _Settings::get();
+      _DifferenceType __minimum_length = std::max<_DifferenceType>(2,
+        std::max(__s.nth_element_minimal_n, __s.partition_minimal_n));
 
       // Break if input range to small.
       while (static_cast<_SequenceIndex>(__end - __begin) >= __minimum_length)
@@ -412,7 +413,7 @@ namespace __gnu_parallel
 	}
 
       // Only at most _Settings::partition_minimal_n __elements __left.
-      __gnu_sequential::sort(__begin, __end, __comp);
+      __gnu_sequential::nth_element(__begin, __nth, __end, __comp);
     }
 
   /** @brief Parallel implementation of std::partial_sort().