mt_allocator.h: Reduce lock contention.
2004-01-23 Stefan Olsson <stefan@snon.net> * include/ext/mt_allocator.h: Reduce lock contention. From-SVN: r76474
This commit is contained in:
Stefan Olsson
Loren J. Rittle
parent
b4eb7029c3
commit
3cfb44c200
@ -1,3 +1,7 @@
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2004-01-23 Stefan Olsson <stefan@snon.net>
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* include/ext/mt_allocator.h: Reduce lock contention.
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2004-01-23 Paolo Carlini <pcarlini@suse.de>
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PR libstdc++/13831
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@ -269,7 +269,7 @@ namespace __gnu_cxx
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size_t thread_id = 0;
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#endif
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block_record* block;
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block_record* block = NULL;
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/*
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* Find out if we have blocks on our freelist.
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@ -280,9 +280,11 @@ namespace __gnu_cxx
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{
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/*
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* Are we using threads?
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* - Yes, lock and check if there are free blocks on the global
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* list (and if not add new ones), get the first one
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* and change owner.
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* - Yes, check if there are free blocks on the global
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* list. If so, grab up to block_count blocks in one
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* lock and change ownership. If the global list is
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* empty, we allocate a new chunk and add those blocks
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* directly to our own freelist (with us as owner).
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* - No, all operations are made directly to global pool 0
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* no need to lock or change ownership but check for free
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* blocks on global list (and if not add new ones) and
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@ -291,57 +293,83 @@ namespace __gnu_cxx
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#ifdef __GTHREADS
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if (__gthread_active_p())
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{
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size_t bin_t = 1 << bin;
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size_t block_count =
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_S_chunk_size /(bin_t + sizeof(block_record));
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__gthread_mutex_lock(_S_bin[bin].mutex);
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if (_S_bin[bin].first[0] == NULL)
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{
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_S_bin[bin].first[0] =
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/*
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* No need to hold the lock when we are adding a
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* whole chunk to our own list
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*/
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__gthread_mutex_unlock(_S_bin[bin].mutex);
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_S_bin[bin].first[thread_id] =
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(block_record*)malloc(_S_chunk_size);
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if (!_S_bin[bin].first[0])
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{
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__gthread_mutex_unlock(_S_bin[bin].mutex);
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__throw_bad_alloc();
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}
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if (!_S_bin[bin].first[thread_id])
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__throw_bad_alloc();
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size_t bin_t = 1 << bin;
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size_t block_count =
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_S_chunk_size /(bin_t + sizeof(block_record));
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_S_bin[bin].free[0] = block_count;
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_S_bin[bin].free[thread_id] = block_count;
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block_count--;
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block = _S_bin[bin].first[0];
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block = _S_bin[bin].first[thread_id];
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while (block_count > 0)
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{
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block->next = (block_record*)((char*)block +
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(bin_t + sizeof(block_record)));
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block->thread_id = thread_id;
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block = block->next;
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block_count--;
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}
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block->next = NULL;
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_S_bin[bin].last[0] = block;
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block->thread_id = thread_id;
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_S_bin[bin].last[thread_id] = block;
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}
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else
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{
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size_t global_count = 0;
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while( _S_bin[bin].first[0] != NULL &&
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global_count < block_count )
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{
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block = _S_bin[bin].first[0];
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if (_S_bin[bin].first[thread_id] == NULL)
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_S_bin[bin].first[thread_id] = block;
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else
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_S_bin[bin].last[thread_id]->next = block;
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_S_bin[bin].last[thread_id] = block;
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block->thread_id = thread_id;
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_S_bin[bin].free[thread_id]++;
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_S_bin[bin].first[0] = _S_bin[bin].first[0]->next;
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global_count++;
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}
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block->next = NULL;
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__gthread_mutex_unlock(_S_bin[bin].mutex);
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}
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block = _S_bin[bin].first[0];
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/*
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* Remove from list and count down the available counter on
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* global pool 0.
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* Return the first newly added block in our list and
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* update the counters
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*/
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_S_bin[bin].first[0] = _S_bin[bin].first[0]->next;
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_S_bin[bin].free[0]--;
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block = _S_bin[bin].first[thread_id];
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_S_bin[bin].first[thread_id] =
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_S_bin[bin].first[thread_id]->next;
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__gthread_mutex_unlock(_S_bin[bin].mutex);
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/*
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* Now that we have removed the block from the global
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* freelist we can change owner and update the used
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* counter for this thread without locking.
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*/
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block->thread_id = thread_id;
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_S_bin[bin].free[thread_id]--;
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_S_bin[bin].used[thread_id]++;
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}
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else
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@ -354,9 +382,7 @@ namespace __gnu_cxx
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size_t bin_t = 1 << bin;
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size_t block_count =
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_S_chunk_size / (bin_t + sizeof(block_record));
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_S_bin[bin].free[0] = block_count;
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_S_chunk_size / (bin_t + sizeof(block_record));
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block_count--;
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block = _S_bin[bin].first[0];
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@ -375,12 +401,9 @@ namespace __gnu_cxx
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block = _S_bin[bin].first[0];
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/*
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* Remove from list and count down the available counter on
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* global pool 0 and increase it's used counter.
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* Remove from list
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*/
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_S_bin[bin].first[0] = _S_bin[bin].first[0]->next;
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_S_bin[bin].free[0]--;
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_S_bin[bin].used[0]++;
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}
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}
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else
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@ -392,8 +415,14 @@ namespace __gnu_cxx
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block = _S_bin[bin].first[thread_id];
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_S_bin[bin].first[thread_id] = _S_bin[bin].first[thread_id]->next;
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_S_bin[bin].free[thread_id]--;
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_S_bin[bin].used[thread_id]++;
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#ifdef __GTHREADS
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if (__gthread_active_p())
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{
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_S_bin[bin].free[thread_id]--;
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_S_bin[bin].used[thread_id]++;
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}
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#endif
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}
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return static_cast<_Tp*>(static_cast<void*>((char*)block + sizeof(block_record)));
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@ -424,7 +453,7 @@ namespace __gnu_cxx
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#endif
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block_record* block = (block_record*)((char*)__p
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- sizeof(block_record));
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- sizeof(block_record));
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/*
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* This block will always be at the back of a list and thus
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@ -465,7 +494,6 @@ namespace __gnu_cxx
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_S_bin[bin].first[thread_id] =
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_S_bin[bin].first[thread_id]->next;
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_S_bin[bin].free[0]++;
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_S_bin[bin].free[thread_id]--;
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remove--;
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@ -509,9 +537,6 @@ namespace __gnu_cxx
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_S_bin[bin].last[0]->next = block;
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_S_bin[bin].last[0] = block;
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_S_bin[bin].free[0]++;
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_S_bin[bin].used[0]--;
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}
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}
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};
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@ -564,7 +589,7 @@ namespace __gnu_cxx
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#ifdef __GTHREADS
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if (__gthread_active_p())
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{
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_S_thread_freelist_first =
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_S_thread_freelist_first =
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(thread_record*)malloc(sizeof(thread_record) * _S_max_threads);
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if (!_S_thread_freelist_first)
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@ -578,7 +603,7 @@ namespace __gnu_cxx
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for (i = 1; i < _S_max_threads; i++)
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{
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_S_thread_freelist_first[i - 1].next =
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&_S_thread_freelist_first[i];
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&_S_thread_freelist_first[i];
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_S_thread_freelist_first[i - 1].id = i;
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}
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@ -605,52 +630,65 @@ namespace __gnu_cxx
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if (!_S_bin)
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__throw_bad_alloc();
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for (size_t bin = 0; bin < _S_no_of_bins; bin++)
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{
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std::size_t __n = _S_max_threads + 1;
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std::size_t __n = 1;
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#ifdef __GTHREADS
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if (__gthread_active_p())
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__n = _S_max_threads + 1;
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#endif
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for (size_t bin = 0; bin < _S_no_of_bins; bin++)
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{
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_S_bin[bin].first = (block_record**)
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malloc(sizeof(block_record*) * __n);
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malloc(sizeof(block_record*) * __n);
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if (!_S_bin[bin].first)
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__throw_bad_alloc();
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_S_bin[bin].last = (block_record**)
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malloc(sizeof(block_record*) * __n);
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malloc(sizeof(block_record*) * __n);
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if (!_S_bin[bin].last)
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__throw_bad_alloc();
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_S_bin[bin].free = (size_t*) malloc(sizeof(size_t) * __n);
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if (!_S_bin[bin].free)
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__throw_bad_alloc();
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_S_bin[bin].used = (size_t*) malloc(sizeof(size_t) * __n);
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if (!_S_bin[bin].used)
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__throw_bad_alloc();
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#ifdef __GTHREADS
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_S_bin[bin].mutex =(__gthread_mutex_t*) malloc(sizeof(__gthread_mutex_t));
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if (__gthread_active_p())
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{
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_S_bin[bin].free = (size_t*) malloc(sizeof(size_t) * __n);
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if (!_S_bin[bin].free)
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__throw_bad_alloc();
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_S_bin[bin].used = (size_t*) malloc(sizeof(size_t) * __n);
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if (!_S_bin[bin].used)
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__throw_bad_alloc();
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_S_bin[bin].mutex =(__gthread_mutex_t*) malloc(sizeof(__gthread_mutex_t));
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#ifdef __GTHREAD_MUTEX_INIT
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{
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// Do not copy a POSIX/gthr mutex once in use.
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__gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
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*_S_bin[bin].mutex = __tmp;
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}
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{
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// Do not copy a POSIX/gthr mutex once in use.
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__gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
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*_S_bin[bin].mutex = __tmp;
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}
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#else
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{ __GTHREAD_MUTEX_INIT_FUNCTION (_S_bin[bin].mutex); }
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{ __GTHREAD_MUTEX_INIT_FUNCTION (_S_bin[bin].mutex); }
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#endif
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}
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#endif
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for (size_t thread = 0; thread <= _S_max_threads; thread++)
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for (size_t thread = 0; thread < __n; thread++)
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{
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_S_bin[bin].first[thread] = NULL;
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_S_bin[bin].last[thread] = NULL;
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_S_bin[bin].free[thread] = 0;
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_S_bin[bin].used[thread] = 0;
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#ifdef __GTHREADS
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if (__gthread_active_p())
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{
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_S_bin[bin].free[thread] = 0;
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_S_bin[bin].used[thread] = 0;
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}
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#endif
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}
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}
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@ -783,6 +821,18 @@ namespace __gnu_cxx
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template<typename _Tp> typename __mt_alloc<_Tp>::bin_record*
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volatile __mt_alloc<_Tp>::_S_bin = NULL;
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template<typename _Tp>
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inline bool
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operator==(const __mt_alloc<_Tp>&,
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const __mt_alloc<_Tp>&)
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{ return true; }
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template<typename _Tp>
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inline bool
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operator!=(const __mt_alloc<_Tp>&,
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const __mt_alloc<_Tp>&)
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{ return false; }
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} // namespace __gnu_cxx
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#endif
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