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src/hotspot/share/memory/metaspace/chunkManager.hpp
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rev 60538 : imported patch jep387-all.patch
@@ -1,7 +1,8 @@
/*
- * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2020 SAP SE. 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.
@@ -24,175 +25,168 @@
#ifndef SHARE_MEMORY_METASPACE_CHUNKMANAGER_HPP
#define SHARE_MEMORY_METASPACE_CHUNKMANAGER_HPP
#include "memory/allocation.hpp"
-#include "memory/binaryTreeDictionary.hpp"
-#include "memory/freeList.hpp"
+#include "memory/metaspace/chunkLevel.hpp"
+#include "memory/metaspace/counter.hpp"
+#include "memory/metaspace/freeChunkList.hpp"
#include "memory/metaspace/metachunk.hpp"
-#include "memory/metaspace/metaspaceStatistics.hpp"
-#include "memory/metaspaceChunkFreeListSummary.hpp"
-#include "utilities/globalDefinitions.hpp"
-
-class ChunkManagerTestAccessor;
namespace metaspace {
-typedef class FreeList<Metachunk> ChunkList;
-typedef BinaryTreeDictionary<Metachunk, FreeList<Metachunk> > ChunkTreeDictionary;
+class VirtualSpaceList;
+struct cm_stats_t;
-// Manages the global free lists of chunks.
-class ChunkManager : public CHeapObj<mtInternal> {
- friend class ::ChunkManagerTestAccessor;
-
- // Free list of chunks of different sizes.
- // SpecializedChunk
- // SmallChunk
- // MediumChunk
- ChunkList _free_chunks[NumberOfFreeLists];
-
- // Whether or not this is the class chunkmanager.
- const bool _is_class;
-
- // Return non-humongous chunk list by its index.
- ChunkList* free_chunks(ChunkIndex index);
-
- // Returns non-humongous chunk list for the given chunk word size.
- ChunkList* find_free_chunks_list(size_t word_size);
-
- // HumongousChunk
- ChunkTreeDictionary _humongous_dictionary;
-
- // Returns the humongous chunk dictionary.
- ChunkTreeDictionary* humongous_dictionary() { return &_humongous_dictionary; }
- const ChunkTreeDictionary* humongous_dictionary() const { return &_humongous_dictionary; }
-
- // Size, in metaspace words, of all chunks managed by this ChunkManager
- size_t _free_chunks_total;
- // Number of chunks in this ChunkManager
- size_t _free_chunks_count;
-
- // Update counters after a chunk was added or removed removed.
- void account_for_added_chunk(const Metachunk* c);
- void account_for_removed_chunk(const Metachunk* c);
-
- // Given a pointer to a chunk, attempts to merge it with neighboring
- // free chunks to form a bigger chunk. Returns true if successful.
- bool attempt_to_coalesce_around_chunk(Metachunk* chunk, ChunkIndex target_chunk_type);
-
- // Helper for chunk merging:
- // Given an address range with 1-n chunks which are all supposed to be
- // free and hence currently managed by this ChunkManager, remove them
- // from this ChunkManager and mark them as invalid.
- // - This does not correct the occupancy map.
- // - This does not adjust the counters in ChunkManager.
- // - Does not adjust container count counter in containing VirtualSpaceNode.
- // Returns number of chunks removed.
- int remove_chunks_in_area(MetaWord* p, size_t word_size);
-
- // Helper for chunk splitting: given a target chunk size and a larger free chunk,
- // split up the larger chunk into n smaller chunks, at least one of which should be
- // the target chunk of target chunk size. The smaller chunks, including the target
- // chunk, are returned to the freelist. The pointer to the target chunk is returned.
- // Note that this chunk is supposed to be removed from the freelist right away.
- Metachunk* split_chunk(size_t target_chunk_word_size, Metachunk* chunk);
-
- public:
-
- ChunkManager(bool is_class);
-
- // Add or delete (return) a chunk to the global freelist.
- Metachunk* chunk_freelist_allocate(size_t word_size);
-
- // Map a size to a list index assuming that there are lists
- // for special, small, medium, and humongous chunks.
- ChunkIndex list_index(size_t size);
-
- // Map a given index to the chunk size.
- size_t size_by_index(ChunkIndex index) const;
-
- bool is_class() const { return _is_class; }
-
- // Convenience accessors.
- size_t medium_chunk_word_size() const { return size_by_index(MediumIndex); }
- size_t small_chunk_word_size() const { return size_by_index(SmallIndex); }
- size_t specialized_chunk_word_size() const { return size_by_index(SpecializedIndex); }
-
- // Take a chunk from the ChunkManager. The chunk is expected to be in
- // the chunk manager (the freelist if non-humongous, the dictionary if
- // humongous).
- void remove_chunk(Metachunk* chunk);
-
- // Return a single chunk of type index to the ChunkManager.
- void return_single_chunk(Metachunk* chunk);
-
- // Add the simple linked list of chunks to the freelist of chunks
- // of type index.
- void return_chunk_list(Metachunk* chunk);
-
- // Total of the space in the free chunks list
- size_t free_chunks_total_words() const { return _free_chunks_total; }
- size_t free_chunks_total_bytes() const { return free_chunks_total_words() * BytesPerWord; }
-
- // Number of chunks in the free chunks list
- size_t free_chunks_count() const { return _free_chunks_count; }
-
- // Remove from a list by size. Selects list based on size of chunk.
- Metachunk* free_chunks_get(size_t chunk_word_size);
-
-#define index_bounds_check(index) \
- assert(is_valid_chunktype(index), "Bad index: %d", (int) index)
-
- size_t num_free_chunks(ChunkIndex index) const {
- index_bounds_check(index);
-
- if (index == HumongousIndex) {
- return _humongous_dictionary.total_free_blocks();
- }
-
- ssize_t count = _free_chunks[index].count();
- return count == -1 ? 0 : (size_t) count;
- }
-
- size_t size_free_chunks_in_bytes(ChunkIndex index) const {
- index_bounds_check(index);
-
- size_t word_size = 0;
- if (index == HumongousIndex) {
- word_size = _humongous_dictionary.total_size();
- } else {
- const size_t size_per_chunk_in_words = _free_chunks[index].size();
- word_size = size_per_chunk_in_words * num_free_chunks(index);
- }
-
- return word_size * BytesPerWord;
- }
-
- MetaspaceChunkFreeListSummary chunk_free_list_summary() const {
- return MetaspaceChunkFreeListSummary(num_free_chunks(SpecializedIndex),
- num_free_chunks(SmallIndex),
- num_free_chunks(MediumIndex),
- num_free_chunks(HumongousIndex),
- size_free_chunks_in_bytes(SpecializedIndex),
- size_free_chunks_in_bytes(SmallIndex),
- size_free_chunks_in_bytes(MediumIndex),
- size_free_chunks_in_bytes(HumongousIndex));
- }
-
-#ifdef ASSERT
- // Debug support
- // Verify free list integrity. slow=true: verify chunk-internal integrity too.
- void verify(bool slow) const;
- void locked_verify(bool slow) const;
-#endif
+// ChunkManager has a somewhat central role.
- void locked_print_free_chunks(outputStream* st);
+// Arenas request chunks from it and, on death, return chunks back to it.
+// It keeps freelists for chunks, one per chunk level, sorted by chunk
+// commit state.
+// To feed the freelists, it allocates root chunks from the associated
+// VirtualSpace below it.
+//
+// ChunkManager directs splitting chunks, if a chunk request cannot be
+// fulfilled directly. It also takes care of merging when chunks are
+// returned to it, before they are added to the freelist.
+//
+// The freelists are double linked double headed; fully committed chunks
+// are added to the front, others to the back.
+//
+// Level
+// +--------------------+ +--------------------+
+// 0 +----| free root chunk |---| free root chunk |---...
+// | +--------------------+ +--------------------+
+// |
+// | +----------+ +----------+
+// 1 +----| |---| |---...
+// | +----------+ +----------+
+// |
+// .
+// .
+// .
+//
+// | +-+ +-+
+// 12 +----| |---| |---...
+// +-+ +-+
+
+
+class ChunkManager : public CHeapObj<mtMetaspace> {
+
+ // A chunk manager is connected to a virtual space list which is used
+ // to allocate new root chunks when no free chunks are found.
+ VirtualSpaceList* const _vslist;
+
+ // Name
+ const char* const _name;
+
+ // Freelists
+ FreeChunkListVector _chunks;
+
+ // Returns true if this manager contains the given chunk. Slow (walks free lists) and
+ // only needed for verifications.
+ DEBUG_ONLY(bool contains_chunk(Metachunk* c) const;)
+
+ // Given a chunk, split it into a target chunk of a smaller size (target level)
+ // at least one, possible more splinter chunks. Splinter chunks are added to the
+ // freelist.
+ // The original chunk must be outside of the freelist and its state must be free.
+ // The resulting target chunk will be located at the same address as the original
+ // chunk, but it will of course be smaller (of a higher level).
+ // The committed areas within the original chunk carry over to the resulting
+ // chunks.
+ void split_chunk_and_add_splinters(Metachunk* c, chunklevel_t target_level);
+
+ // See get_chunk(s,s,s)
+ Metachunk* get_chunk_locked(size_t preferred_word_size, size_t min_word_size, size_t min_committed_words);
+
+ // Uncommit all chunks equal or below the given level.
+ void uncommit_free_chunks(chunklevel_t max_level);
+
+ // Return a single chunk to the freelist without doing any merging, and adjust accounting.
+ void return_chunk_simple_locked(Metachunk* c);
+
+ // See return_chunk().
+ void return_chunk_locked(Metachunk* c);
+
+public:
+
+ // Creates a chunk manager with a given name (which is for debug purposes only)
+ // and an associated space list which will be used to request new chunks from
+ // (see get_chunk())
+ ChunkManager(const char* name, VirtualSpaceList* space_list);
+
+ // On success, returns a chunk of level of <preferred_level>, but at most <max_level>.
+ // The first first <min_committed_words> of the chunk are guaranteed to be committed.
+ // On error, will return NULL.
+ //
+ // This function may fail for two reasons:
+ // - Either we are unable to reserve space for a new chunk (if the underlying VirtualSpaceList
+ // is non-expandable but needs expanding - aka out of compressed class space).
+ // - Or, if the necessary space cannot be committed because we hit a commit limit.
+ // This may be either the GC threshold or MaxMetaspaceSize.
+ Metachunk* get_chunk(chunklevel_t preferred_level, chunklevel_t max_level, size_t min_committed_words);
+
+ // Convenience function - get a chunk of a given level, uncommitted.
+ Metachunk* get_chunk(chunklevel_t lvl) { return get_chunk(lvl, lvl, 0); }
+
+ // Return a single chunk to the ChunkManager and adjust accounting. May merge chunk
+ // with neighbors.
+ // Happens after a Classloader was unloaded and releases its metaspace chunks.
+ // !! Notes:
+ // 1) After this method returns, c may not be valid anymore. ** Do not access c after this function returns **.
+ // 2) This function will not remove c from its current chunk list. This has to be done by the caller prior to
+ // calling this method.
+ void return_chunk(Metachunk* c);
+
+ // Given a chunk c, which must be "in use" and must not be a root chunk, attempt to
+ // enlarge it in place by claiming its trailing buddy.
+ //
+ // This will only work if c is the leader of the buddy pair and the trailing buddy is free.
+ //
+ // If successful, the follower chunk will be removed from the freelists, the leader chunk c will
+ // double in size (level decreased by one).
+ //
+ // On success, true is returned, false otherwise.
+ bool attempt_enlarge_chunk(Metachunk* c);
+
+ // Attempt to reclaim free areas in metaspace wholesale:
+ // - first, attempt to purge nodes of the backing virtual space list: nodes which are completely
+ // unused get unmapped and deleted completely.
+ // - second, it will uncommit free chunks depending on commit granule size.
+ void purge();
+
+ // Run verifications. slow=true: verify chunk-internal integrity too.
+ DEBUG_ONLY(void verify(bool slow) const;)
+ DEBUG_ONLY(void verify_locked(bool slow) const;)
+
+ // Returns the name of this chunk manager.
+ const char* name() const { return _name; }
+
+ // Returns total number of chunks
+ int total_num_chunks() const { return _chunks.num_chunks(); }
+
+ // Returns number of words in all free chunks (regardless of commit state).
+ size_t total_word_size() const { return _chunks.word_size(); }
+
+ // Returns number of committed words in all free chunks.
+ size_t total_committed_word_size() const { return _chunks.committed_word_size(); }
+
+ // Update statistics.
+ void add_to_statistics(cm_stats_t* out) const;
+
+ void print_on(outputStream* st) const;
+ void print_on_locked(outputStream* st) const;
+
+public:
+
+ // Convenience methods to return the global class-space chunkmanager
+ // and non-class chunkmanager, respectively.
+ static ChunkManager* chunkmanager_class();
+ static ChunkManager* chunkmanager_nonclass();
- // Fill in current statistic values to the given statistics object.
- void collect_statistics(ChunkManagerStatistics* out) const;
};
} // namespace metaspace
-
#endif // SHARE_MEMORY_METASPACE_CHUNKMANAGER_HPP
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