re PR libstdc++/29179 (bugs in mt_allocator)

2006-09-25  Paolo Carlini  <pcarlini@suse.de>

	PR libstdc++/29179
	* include/ext/mt_allocator.h (__pool_base): Adjust/extend
	documentation in comments.

From-SVN: r117193

1 files changed, 10 insertions, 6 deletions

diff --git a/libstdc++-v3/include/ext/mt_allocator.h b/libstdc++-v3/include/ext/mt_allocator.h
index 4dcd4373e4e..bc2d61f6eec 100644
--- a/libstdc++-v3/include/ext/mt_allocator.h
+++ b/libstdc++-v3/include/ext/mt_allocator.h
@@ -50,7 +50,7 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
   struct __pool_base
   {
     // Using short int as type for the binmap implies we are never
-    // caching blocks larger than 65535 with this allocator.
+    // caching blocks larger than 32768 with this allocator.
     typedef unsigned short int _Binmap_type;
 
     // Variables used to configure the behavior of the allocator,
@@ -73,19 +73,23 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
       // Allocation requests (after round-up to power of 2) below
       // this value will be handled by the allocator. A raw new/
       // call will be used for requests larger than this value.
+      // NB: Must be much smaller than _M_chunk_size and in any
+      // case <= 32768.
       size_t	_M_max_bytes; 
-      
+
       // Size in bytes of the smallest bin.
-      // NB: Must be a power of 2 and >= _M_align.
+      // NB: Must be a power of 2 and >= _M_align (and of course
+      // much smaller than _M_max_bytes).
       size_t	_M_min_bin;
-      
+
       // In order to avoid fragmenting and minimize the number of
       // new() calls we always request new memory using this
       // value. Based on previous discussions on the libstdc++
       // mailing list we have choosen the value below.
       // See http://gcc.gnu.org/ml/libstdc++/2001-07/msg00077.html
+      // NB: At least one order of magnitude > _M_max_bytes. 
       size_t	_M_chunk_size;
-      
+
       // The maximum number of supported threads. For
       // single-threaded operation, use one. Maximum values will
       // vary depending on details of the underlying system. (For
@@ -93,7 +97,7 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
       // /proc/sys/kernel/threads-max, while Linux 2.6.6 reports
       // 65534)
       size_t 	_M_max_threads;
-      
+
       // Each time a deallocation occurs in a threaded application
       // we make sure that there are no more than
       // _M_freelist_headroom % of used memory on the freelist. If