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src/hotspot/share/memory/metaspace/virtualSpaceNode.hpp
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rev 60538 : imported patch jep387-core.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.
@@ -23,141 +24,270 @@
*/
#ifndef SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
#define SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
-#include "memory/virtualspace.hpp"
+
+#include "memory/allocation.hpp"
+#include "memory/metaspace/counter.hpp"
+#include "memory/metaspace/commitMask.hpp"
+#include "memory/metaspace/rootChunkArea.hpp"
+#include "memory/metaspace/settings.hpp"
#include "memory/memRegion.hpp"
+#include "memory/virtualspace.hpp"
#include "utilities/debug.hpp"
+#include "utilities/bitMap.hpp"
#include "utilities/globalDefinitions.hpp"
+
class outputStream;
namespace metaspace {
-class Metachunk;
-class ChunkManager;
-class OccupancyMap;
+class CommitLimiter;
+class FreeChunkListVector;
+
+// VirtualSpaceNode manages a single contiguous address range of metaspace. Logically that memory
+// region is split up into a sequence of "root chunk areas", each one containing one root chunk
+// or splinters of a root chunk.
+//
+// The underlying memory is also logically divided into a number of "commit granules", units of memory
+// which may be committed or uncommitted independently from each other.
+//
+// (Both root chunk areas and commit granules have not much to do with each other - one is a way to
+// reserve memory for the upper regions, see ChunkManager. One is a way to manage commited memory.)
+//
+// VirtualSpaceNode:
+// - exposes a function to allocate a new root chunk (see VirtualSpaceNode::allocate_root_chunk()).
+//
+// - knows about the commit state of the memory region - which commit granule are committed, which
+// are not. It exposes functions to commit and uncommit regions (without actively committing
+// itself)
+//
+// - It has a reference to a "CommitLimiter", an interface to query whether committing is
+// possible. That interface hides the various ways committing may be limited (GC threshold,
+// MaxMetaspaceSize, ...)
+//
+// - It uses ReservedSpace to reserve its memory. It either owns the ReservedSpace or that
+// space got handed in from outside (ccs).
+//
+//
+//
+//
+// | root chunk area | root chunk area | root chunk area | <-- root chunk areas
+//
+// +-----------------------------------------------------------------------------------------------+
+// | |
+// | `VirtualSpaceNode` memory |
+// | |
+// +-----------------------------------------------------------------------------------------------+
+//
+// |x| |x|x|x| | | | |x|x|x| | | |x|x| | | |x|x|x|x| | | | | | | | |x| | | |x|x|x|x| | | |x| | | |x| <-- commit granules
+//
+// (x = committed)
+//
-// A VirtualSpaceList node.
class VirtualSpaceNode : public CHeapObj<mtClass> {
- friend class VirtualSpaceList;
// Link to next VirtualSpaceNode
VirtualSpaceNode* _next;
- // Whether this node is contained in class or metaspace.
- const bool _is_class;
-
- // total in the VirtualSpace
+ // The underlying space. This has been either created by this node
+ // and is owned by it, or has been handed in from outside (e.g. in
+ // case of CompressedClassSpace).
ReservedSpace _rs;
- VirtualSpace _virtual_space;
- MetaWord* _top;
- // count of chunks contained in this VirtualSpace
- uintx _container_count;
-
- OccupancyMap* _occupancy_map;
-
- // Convenience functions to access the _virtual_space
- char* low() const { return virtual_space()->low(); }
- char* high() const { return virtual_space()->high(); }
- char* low_boundary() const { return virtual_space()->low_boundary(); }
- char* high_boundary() const { return virtual_space()->high_boundary(); }
-
- // The first Metachunk will be allocated at the bottom of the
- // VirtualSpace
- Metachunk* first_chunk() { return (Metachunk*) bottom(); }
-
- // Committed but unused space in the virtual space
- size_t free_words_in_vs() const;
-
- // True if this node belongs to class metaspace.
- bool is_class() const { return _is_class; }
-
- // Helper function for take_from_committed: allocate padding chunks
- // until top is at the given address.
- void allocate_padding_chunks_until_top_is_at(MetaWord* target_top);
-
- public:
-
- VirtualSpaceNode(bool is_class, size_t byte_size);
- VirtualSpaceNode(bool is_class, ReservedSpace rs) :
- _next(NULL), _is_class(is_class), _rs(rs), _top(NULL), _container_count(0), _occupancy_map(NULL) {}
- ~VirtualSpaceNode();
-
- // Convenience functions for logical bottom and (committed) end
- MetaWord* bottom() const { return (MetaWord*) _virtual_space.low(); }
- MetaWord* end() const { return (MetaWord*) _virtual_space.high(); }
-
- const OccupancyMap* occupancy_map() const { return _occupancy_map; }
- OccupancyMap* occupancy_map() { return _occupancy_map; }
-
- bool contains(const void* ptr) { return ptr >= low() && ptr < high(); }
- size_t reserved_words() const { return _virtual_space.reserved_size() / BytesPerWord; }
- size_t committed_words() const { return _virtual_space.actual_committed_size() / BytesPerWord; }
+ // True if the node owns the reserved space, false if not.
+ const bool _owns_rs;
- bool is_pre_committed() const { return _virtual_space.special(); }
+ // Start pointer of the area.
+ MetaWord* const _base;
- // address of next available space in _virtual_space;
- // Accessors
- VirtualSpaceNode* next() { return _next; }
- void set_next(VirtualSpaceNode* v) { _next = v; }
+ // Size, in words, of the whole node
+ const size_t _word_size;
- void set_top(MetaWord* v) { _top = v; }
+ // Size, in words, of the range of this node which has been handed out in
+ // the form of root chunks.
+ size_t _used_words;
+
+ // The bitmap describing the commit state of the region:
+ // Each bit covers a region of 64K (see constants::commit_granule_size).
+ CommitMask _commit_mask;
+
+ // An array/lookup table of RootChunkArea objects. Each one describes a root chunk area.
+ RootChunkAreaLUT _root_chunk_area_lut;
+
+ // Limiter object to ask before expanding the committed size of this node.
+ CommitLimiter* const _commit_limiter;
+
+ // Points to outside size counters which we are to increase/decrease when we commit/uncommit
+ // space from this node.
+ SizeCounter* const _total_reserved_words_counter;
+ SizeCounter* const _total_committed_words_counter;
+
+ /// committing, uncommitting ///
+
+ // Given a pointer into this node, calculate the start of the commit granule
+ // the pointer points into.
+ MetaWord* calc_start_of_granule(MetaWord* p) const {
+ DEBUG_ONLY(check_pointer(p));
+ return align_down(p, Settings::commit_granule_bytes());
+ }
+
+ // Given an address range, ensure it is committed.
+ //
+ // The range has to be aligned to granule size.
+ //
+ // Function will:
+ // - check how many granules in that region are uncommitted; If all are committed, it
+ // returns true immediately.
+ // - check if committing those uncommitted granules would bring us over the commit limit
+ // (GC threshold, MaxMetaspaceSize). If true, it returns false.
+ // - commit the memory.
+ // - mark the range as committed in the commit mask
+ //
+ // Returns true if success, false if it did hit a commit limit.
+ bool commit_range(MetaWord* p, size_t word_size);
+
+ //// creation ////
+
+ // Create a new empty node spanning the given given reserved space.
+ VirtualSpaceNode(ReservedSpace rs, bool owns_rs, CommitLimiter* limiter,
+ SizeCounter* reserve_counter, SizeCounter* commit_counter);
+
+public:
+
+ // Create a node of a given size (it will create its own space).
+ static VirtualSpaceNode* create_node(size_t word_size, CommitLimiter* limiter, SizeCounter* reserve_words_counter,
+ SizeCounter* commit_words_counter);
+
+ // Create a node over an existing space
+ static VirtualSpaceNode* create_node(ReservedSpace rs, CommitLimiter* limiter, SizeCounter* reserve_words_counter,
+ SizeCounter* commit_words_counter);
- // Accessors
- VirtualSpace* virtual_space() const { return (VirtualSpace*) &_virtual_space; }
-
- // Returns true if "word_size" is available in the VirtualSpace
- bool is_available(size_t word_size) { return word_size <= pointer_delta(end(), _top, sizeof(MetaWord)); }
-
- MetaWord* top() const { return _top; }
- void inc_top(size_t word_size) { _top += word_size; }
-
- uintx container_count() { return _container_count; }
- void inc_container_count();
- void dec_container_count();
-
- // used and capacity in this single entry in the list
- size_t used_words_in_vs() const;
- size_t capacity_words_in_vs() const;
-
- bool initialize();
-
- // get space from the virtual space
- Metachunk* take_from_committed(size_t chunk_word_size);
-
- // Allocate a chunk from the virtual space and return it.
- Metachunk* get_chunk_vs(size_t chunk_word_size);
-
- // Expands the committed space by at least min_words words.
- bool expand_by(size_t min_words, size_t preferred_words);
+ ~VirtualSpaceNode();
- // In preparation for deleting this node, remove all the chunks
- // in the node from any freelist.
- void purge(ChunkManager* chunk_manager);
+ // Note: public for gtests only, could be private.
+ MetaWord* base() const { return _base; }
- // If an allocation doesn't fit in the current node a new node is created.
- // Allocate chunks out of the remaining committed space in this node
- // to avoid wasting that memory.
- // This always adds up because all the chunk sizes are multiples of
- // the smallest chunk size.
- void retire(ChunkManager* chunk_manager);
+ // Reserved size of the whole node.
+ size_t word_size() const { return _word_size; }
- void print_on(outputStream* st) const { print_on(st, K); }
- void print_on(outputStream* st, size_t scale) const;
- void print_map(outputStream* st, bool is_class) const;
+ //// Chunk allocation, splitting, merging /////
- // Debug support
- DEBUG_ONLY(void mangle();)
- // Verify counters and basic structure. Slow mode: verify all chunks in depth and occupancy map.
- DEBUG_ONLY(void verify(bool slow);)
- // Verify that all free chunks in this node are ideally merged
- // (there should not be multiple small chunks where a large chunk could exist.)
- DEBUG_ONLY(void verify_free_chunks_are_ideally_merged();)
+ // Allocate a root chunk from this node. Will fail and return NULL if the node is full
+ // - if we used up the whole address space of this node's memory region.
+ // (in case this node backs compressed class space, this is how we hit
+ // CompressedClassSpaceSize).
+ // Note that this just returns reserved memory; caller must take care of committing this
+ // chunk before using it.
+ Metachunk* allocate_root_chunk();
+
+ // Given a chunk c, split it recursively until you get a chunk of the given target_level.
+ //
+ // The resulting target chunk resides at the same address as the original chunk.
+ // The resulting splinters are added to freelists.
+ void split(chunklevel_t target_level, Metachunk* c, FreeChunkListVector* freelists);
+
+ // Given a chunk, attempt to merge it recursively with its neighboring chunks.
+ //
+ // If successful (merged at least once), returns address of
+ // the merged chunk; NULL otherwise.
+ //
+ // The merged chunks are removed from the freelists.
+ //
+ // !!! Please note that if this method returns a non-NULL value, the
+ // original chunk will be invalid and should not be accessed anymore! !!!
+ Metachunk* merge(Metachunk* c, FreeChunkListVector* freelists);
+
+ // 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, FreeChunkListVector* freelists);
+
+ // Attempts to purge the node:
+ //
+ // If all chunks living in this node are free, they will all be removed from
+ // the freelist they currently reside in. Then, the node will be deleted.
+ //
+ // Returns true if the node has been deleted, false if not.
+ // !! If this returns true, do not access the node from this point on. !!
+ bool attempt_purge(FreeChunkListVector* freelists);
+
+ // Attempts to uncommit free areas according to the rules set in settings.
+ // Returns number of words uncommitted.
+ size_t uncommit_free_areas();
+
+ /// misc /////
+
+ // Returns size, in words, of the used space in this node alone.
+ // (Notes:
+ // - This is the space handed out to the ChunkManager, so it is "used" from the viewpoint of this node,
+ // but not necessarily used for Metadata.
+ // - This may or may not be committed memory.
+ size_t used_words() const { return _used_words; }
+
+ // Returns size, in words, of how much space is left in this node alone.
+ size_t free_words() const { return _word_size - _used_words; }
+
+ // Returns size, in words, of committed space in this node alone.
+ // Note: iterates over commit mask and hence may be a tad expensive on large nodes.
+ size_t committed_words() const;
+
+ //// Committing/uncommitting memory /////
+
+ // Given an address range, ensure it is committed.
+ //
+ // The range does not have to be aligned to granule size. However, the function will always commit
+ // whole granules.
+ //
+ // Function will:
+ // - check how many granules in that region are uncommitted; If all are committed, it
+ // returns true immediately.
+ // - check if committing those uncommitted granules would bring us over the commit limit
+ // (GC threshold, MaxMetaspaceSize). If true, it returns false.
+ // - commit the memory.
+ // - mark the range as committed in the commit mask
+ //
+ // Returns true if success, false if it did hit a commit limit.
+ bool ensure_range_is_committed(MetaWord* p, size_t word_size);
+
+ // Given an address range (which has to be aligned to commit granule size):
+ // - uncommit it
+ // - mark it as uncommitted in the commit mask
+ void uncommit_range(MetaWord* p, size_t word_size);
+
+ //// List stuff ////
+ VirtualSpaceNode* next() const { return _next; }
+ void set_next(VirtualSpaceNode* vsn) { _next = vsn; }
+
+
+ /// Debug stuff ////
+
+ // Print a description about this node.
+ void print_on(outputStream* st) const;
+
+ // Verify counters and basic structure. Slow mode: verify all chunks in depth
+ bool contains(const MetaWord* p) const {
+ return p >= _base && p < _base + _used_words;
+ }
+
+#ifdef ASSERT
+ void check_pointer(const MetaWord* p) const {
+ assert(contains(p), "invalid pointer");
+ }
+ void verify(bool slow) const;
+ void verify_locked(bool slow) const;
+#endif
};
+
} // namespace metaspace
#endif // SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
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