--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/memory/metaspace/leftOverBins.hpp Fri Nov 01 10:28:15 2019 +0100
@@ -0,0 +1,219 @@
+/*
+ * Copyright (c) 2019, SAP SE. All rights reserved.
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_MEMORY_METASPACE_LEFTOVERBINS_HPP
+#define SHARE_MEMORY_METASPACE_LEFTOVERBINS_HPP
+
+#include "memory/allocation.hpp"
+#include "memory/metaspace/counter.hpp"
+#include "utilities/bitMap.hpp"
+#include "utilities/debug.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+
+class outputStream;
+
+namespace metaspace {
+
+// The LeftOverManager is responsible for managing small leftover-
+// and deallocated blocks.
+// They come from two sources:
+// a) the leftover space left in a chunk when a chunk gets retired
+// because it cannot serve a requested allocation. These blocks
+// can be largeish (100s - 1000s of words).
+// b) when a metaspace allocation is deallocated prematurely - e.g.
+// due to interrupted class loading. These blocks are small or
+// very small.
+
+class BinMap {
+
+ typedef uint32_t mask_type;
+ mask_type _mask;
+
+ static mask_type mask_for_pos(int pos) { return 1 << pos; }
+
+public:
+
+ BinMap() : _mask(0) {}
+
+ bool all_zero() const { return _mask == 0; }
+
+ bool get_bit(int pos) const { return (_mask & mask_for_pos(pos)) != 0 ? true : false; }
+ void set_bit(int pos) { _mask |= mask_for_pos(pos); }
+ void clr_bit(int pos) { _mask &= ~mask_for_pos(pos); }
+
+ // Starting at (including) pos, find the position of the next 1 bit.
+ // Return -1 if not found.
+ inline int find_next_set_bit(int pos) const;
+
+ static int size() { return sizeof(mask_type) * 8; }
+
+};
+
+struct block_t {
+ block_t* next;
+ size_t size;
+};
+
+struct block_stats_t {
+ size_t word_size;
+ int num_blocks;
+};
+
+template <
+ size_t min_word_size,
+ size_t spread,
+ int num_bins
+>
+class Bins {
+
+ STATIC_ASSERT(sizeof(block_t) <= (min_word_size * BytesPerWord));
+
+ block_t* _bins[num_bins];
+
+ BinMap _mask;
+
+ // e.g. spread = 4
+ //
+ // sz bno (put) bno (get)
+ // (guarant)
+ // 0 00 00
+ // 1 00 01
+ // 2 00 01
+ // 3 00 01
+ // 4 01 01
+ // 5 01 02
+ // 6 01 02
+ // 7 01 02
+ // 8 02 02
+ // 9 02 03
+ // 10 02 03
+ // 11 02 03
+ //
+ // put -> no = wordsize / spread
+ //
+ // get -> no = (req_wordsize + spread - 1) / spread
+
+ // The bin number for a given word size.
+ static int bin_for_size(size_t word_size) {
+ assert(word_size >= min_word_size && word_size < maximal_word_size(),
+ "Word size oob (" SIZE_FORMAT ")", word_size);
+ return (word_size - min_word_size) / spread;
+ }
+
+ // [minimal, maximal) size of blocks which are held in a bin.
+ // Note that when taking a block out of the bin, only the minimum block size
+ // is guaranteed.
+ static size_t minimal_word_size_in_bin(int bno) {
+ return min_word_size + (bno * spread);
+ }
+ static size_t maximal_word_size_in_bin(int bno) {
+ return minimal_word_size_in_bin(bno) + spread;
+ }
+
+public:
+
+ Bins() : _mask() {
+ assert(BinMap::size() >= num_bins, "mask too small");
+ ::memset(_bins, 0, sizeof(_bins));
+ }
+
+ // [min, max) word size
+ static size_t minimal_word_size() { return min_word_size; }
+ static size_t maximal_word_size() { return min_word_size + (spread * num_bins); }
+
+ inline void put(MetaWord* p, size_t word_size);
+
+ inline block_t* get(size_t word_size);
+
+#ifdef ASSERT
+ void verify() const;
+#endif
+
+ void statistics(block_stats_t* stats) const;
+
+ void print(outputStream* st) const;
+
+};
+
+
+class LeftOverManager : public CHeapObj<mtInternal> {
+
+ typedef Bins<2, 2, 16> VerySmallBinsType;
+ VerySmallBinsType _very_small_bins;
+
+ block_t* _large_block_reserve;
+
+ // The current large block we gnaw on
+ MetaWord* _current;
+ size_t _current_size;
+
+ SizeCounter _total_word_size;
+
+ // Take the topmost block from the large block reserve list
+ // and make it current.
+ inline void prime_current();
+
+ // Allocate from current block. Returns NULL if current block
+ // is too small.
+ inline MetaWord* alloc_from_current(size_t word_size);
+
+ void large_block_statistics(block_stats_t* stats) const;
+
+public:
+
+ static size_t minimal_word_size() {
+ return VerySmallBinsType::minimal_word_size();
+ }
+
+ LeftOverManager() :
+ _very_small_bins(),
+ _large_block_reserve(NULL),
+ _current(NULL),
+ _current_size(0)
+ {}
+
+ inline void add_block(MetaWord* p, size_t word_size);
+
+ inline MetaWord* get_block(size_t requested_word_size);
+
+#ifdef ASSERT
+ void verify() const;
+#endif
+
+ void statistics(block_stats_t* stats) const;
+
+ void print(outputStream* st, bool detailed = false) const;
+
+ size_t total_word_size() const { return _total_word_size.get(); }
+
+};
+
+
+
+
+} // namespace metaspace
+
+#endif // SHARE_MEMORY_METASPACE_CHUNKMANAGER_HPP