From ab40b100d3e1676c60d3ccd0765a45736471beaf Mon Sep 17 00:00:00 2001
From: Paolo Carlini <pcarlini@suse.de>
Date: Fri, 2 Apr 2004 19:51:21 +0000
Subject: [PATCH] mt_allocator.h (__mt_alloc<>::deallocate): Rearrange
arithmetic to avoid computing two divisions at each deallocation.
2004-04-02 Paolo Carlini <pcarlini@suse.de>
* include/ext/mt_allocator.h (__mt_alloc<>::deallocate):
Rearrange arithmetic to avoid computing two divisions at
each deallocation.
From-SVN: r80356
---
libstdc++-v3/ChangeLog | 6 ++++++
libstdc++-v3/include/ext/mt_allocator.h | 26 ++++++++++++-------------
2 files changed, 18 insertions(+), 14 deletions(-)
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index b47d26e0a3de..3248c3243bca 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,9 @@
+2004-04-02 Paolo Carlini <pcarlini@suse.de>
+
+ * include/ext/mt_allocator.h (__mt_alloc<>::deallocate):
+ Rearrange arithmetic to avoid computing two divisions at
+ each deallocation.
+
2004-04-01 Paolo Carlini <pcarlini@suse.de>
* include/ext/mt_allocator.h (__mt_alloc<>::_S_initialize):
diff --git a/libstdc++-v3/include/ext/mt_allocator.h b/libstdc++-v3/include/ext/mt_allocator.h
index 8edbaaaf50fb..d69b0e1ebd91 100644
--- a/libstdc++-v3/include/ext/mt_allocator.h
+++ b/libstdc++-v3/include/ext/mt_allocator.h
@@ -434,25 +434,23 @@ namespace __gnu_cxx
#ifdef __GTHREADS
if (__gthread_active_p())
{
- // Calculate the number of records to remove from our freelist.
+ // Calculate the number of records to remove from our freelist:
+ // in order to avoid too much contention we wait until the
+ // number of records is "high enough".
const size_t __thread_id = _S_get_thread_id();
- int __remove = (__bin._M_free[__thread_id]
- - (__bin._M_used[__thread_id]
- / _S_options._M_freelist_headroom));
-
- // The calculation above will almost always tell us to
- // remove one or two records at a time, but this creates too
- // much contention when locking and therefore we wait until
- // the number of records is "high enough".
- int __cond1 = static_cast<int>(100 * (_S_bin_size - __which));
- int __cond2 = static_cast<int>(__bin._M_free[__thread_id]
- / _S_options._M_freelist_headroom);
- if (__remove > __cond1 && __remove > __cond2)
+
+ long __remove = ((__bin._M_free[__thread_id]
+ * _S_options._M_freelist_headroom)
+ - __bin._M_used[__thread_id]);
+ if (__remove > static_cast<long>(100 * (_S_bin_size - __which)
+ * _S_options._M_freelist_headroom)
+ && __remove > static_cast<long>(__bin._M_free[__thread_id]))
{
__gthread_mutex_lock(__bin._M_mutex);
_Block_record* __tmp = __bin._M_first[__thread_id];
_Block_record* __first = __tmp;
- const int __removed = __remove;
+ __remove /= _S_options._M_freelist_headroom;
+ const long __removed = __remove;
while (__remove > 1)
{
__tmp = __tmp->_M_next;
--
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