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mt_allocator.html: Add docs for _Tune.

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2004-07-13  Benjamin Kosnik  <bkoz@redhat.com>

	* docs/html/ext/mt_allocator.html: Add docs for _Tune.
	* include/ext/mt_allocator.h (__mt_alloc::_S_get_options): Make public.
	(__mt_alloc::_S_set_options): Same.
	Add to comments.

2004-07-13  Benjamin Kosnik  <bkoz@redhat.com>

	* acinclude.m4 (GLIBCXX_ENABLE_ALLOCATOR): Add allocator defaults
	for linux.
	* configure: Regenerated.

From-SVN: r84674
This commit is contained in:
Benjamin Kosnik 2004-07-14 06:37:17 +00:00 committed by Benjamin Kosnik
parent 70049c7ce2
commit 780028b6cf
5 changed files with 1932 additions and 944 deletions
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13
libstdc++-v3/ChangeLog
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@ -1,3 +1,16 @@
2004-07-13 Benjamin Kosnik <bkoz@redhat.com>
* docs/html/ext/mt_allocator.html: Add docs for _Tune.
* include/ext/mt_allocator.h (__mt_alloc::_S_get_options): Make public.
(__mt_alloc::_S_set_options): Same.
Add to comments.
2004-07-13 Benjamin Kosnik <bkoz@redhat.com>
* acinclude.m4 (GLIBCXX_ENABLE_ALLOCATOR): Add allocator defaults
for linux.
* configure: Regenerated.
2004-07-13 Paolo Carlini <pcarlini@suse.de>
* testsuite/22_locale/locale/cons/12658_thread.cc: Move/rename

6
libstdc++-v3/acinclude.m4
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@ -1163,13 +1163,17 @@ AC_DEFUN([GLIBCXX_ENABLE_ALLOCATOR], [
enable_libstdcxx_allocator=auto
fi
# Either a known package, or "auto"
# Either a known package, or "auto". Auto implies the default choice
# for a particular platform.
enable_libstdcxx_allocator_flag=$enable_libstdcxx_allocator
# Probe for host-specific support if no specific model is specified.
# Default to "new".
if test $enable_libstdcxx_allocator_flag = auto; then
case ${target_os} in
linux* | gnu* | kfreebsd*-gnu | knetbsd*-gnu)
enable_libstdcxx_allocator_flag=mt
;;
*)
enable_libstdcxx_allocator_flag=new
;;

2765
libstdc++-v3/configure vendored
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62
libstdc++-v3/docs/html/ext/mt_allocator.html
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@ -53,6 +53,61 @@ The aim of this document is to describe - from a application point of
view - the "inner workings" of the allocator.
</p>
<h3 class="left">
<a name="init">Tunable parameters</a>
</h3>
<p>Certain allocation parameters can be modified on a per-type
basis. There exists a nested <pre>struct _Tune</pre> that contains all
these parameters, which include settings for
</p>
<ul>
<li>Alignment </li>
<li>Maximum bytes before calling <code>::operator new</code> directly</li>
<li>Minimum bytes</li>
<li>Size of underlying global allocations</li>
<li>Maximum number of supported threads</li>
<li>Migration of deallocations to the global free list</li>
<li>Shunt for global <code>new</code> and <code>delete</code></li>
</ul>
<p>Adjusting parameters for a given instance of an allocator can only
happen before any allocations take place, when the allocator itself is
initialized. For instance:
</p>
<pre>
#include &lt;ext/mt_allocator.h&gt;
struct pod
{
int i;
int j;
};
int main()
{
typedef pod value_type;
typedef __gnu_cxx::__mt_alloc&lt;value_type&gt; allocator_type;
typedef allocator_type::_Tune tune_type;
tune_type t_default;
tune_type t_opt(16, 5120, 32, 5120, 20, 10, false);
tune_type t_single(16, 5120, 32, 5120, 1, 10, false);
tune_type t;
t = allocator_type::_S_get_options();
allocator_type::_S_set_options(t_opt);
t = allocator_type::_S_get_options();
allocator_type a;
allocator_type::pointer p1 = a.allocate(128);
allocator_type::pointer p2 = a.allocate(5128);
a.deallocate(p1, 128);
a.deallocate(p2, 5128);
return 0;
}
</pre>
<h3 class="left">
<a name="init">Initialization</a>
@ -60,14 +115,9 @@ view - the "inner workings" of the allocator.
<p>
The static variables (pointers to freelists, tuning parameters etc)
are initialized to their default values at file scope, i.e.:
are initialized as above, or are set to the global defaults.
</p>
<pre>
template&lt;typename _Tp&gt; size_t
__mt_alloc&lt;_Tp&gt;::_S_freelist_headroom = 10;
</pre>
<p>
The very first allocate() call will always call the _S_init() function.
In order to make sure that this function is called exactly once we make use

30
libstdc++-v3/include/ext/mt_allocator.h
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@ -139,8 +139,12 @@ namespace __gnu_cxx
// See http://gcc.gnu.org/ml/libstdc++/2001-07/msg00077.html
size_t _M_chunk_size;
// The maximum number of supported threads. Our Linux 2.4.18
// reports 4070 in /proc/sys/kernel/threads-max
// The maximum number of supported threads. For
// single-threaded operation, use one. Maximum values will
// vary depending on details of the underlying system. (For
// instance, Linux 2.4.18 reports 4070 in
// /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
@ -172,6 +176,17 @@ namespace __gnu_cxx
{ }
};
static const _Tune
_S_get_options()
{ return _S_options; }
static void
_S_set_options(_Tune __t)
{
if (!_S_init)
_S_options = __t;
}
private:
// We need to create the initial lists and set up some variables
// before we can answer to the first request for memory.
@ -186,17 +201,6 @@ namespace __gnu_cxx
// Configuration options.
static _Tune _S_options;
static const _Tune
_S_get_options()
{ return _S_options; }
static void
_S_set_options(_Tune __t)
{
if (!_S_init)
_S_options = __t;
}
// Using short int as type for the binmap implies we are never
// caching blocks larger than 65535 with this allocator
typedef unsigned short int _Binmap_type;