8d0e04d42f
Recent huge allocation refactoring associates huge allocations with arenas, but it remains necessary to quickly look up huge allocation metadata during reallocation/deallocation. A global radix tree remains a good solution to this problem, but locking would have become the primary bottleneck after (upcoming) migration of chunk management from global to per arena data structures. This lock-free implementation uses double-checked reads to traverse the tree, so that in the steady state, each read or write requires only a single atomic operation. This implementation also assures that no more than two tree levels actually exist, through a combination of careful virtual memory allocation which makes large sparse nodes cheap, and skipping the root node on x64 (possible because the top 16 bits are all 0 in practice).
66 lines
2.1 KiB
C
66 lines
2.1 KiB
C
/******************************************************************************/
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#ifdef JEMALLOC_H_TYPES
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/*
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* Size and alignment of memory chunks that are allocated by the OS's virtual
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* memory system.
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*/
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#define LG_CHUNK_DEFAULT 22
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/* Return the chunk address for allocation address a. */
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#define CHUNK_ADDR2BASE(a) \
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((void *)((uintptr_t)(a) & ~chunksize_mask))
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/* Return the chunk offset of address a. */
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#define CHUNK_ADDR2OFFSET(a) \
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((size_t)((uintptr_t)(a) & chunksize_mask))
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/* Return the smallest chunk multiple that is >= s. */
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#define CHUNK_CEILING(s) \
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(((s) + chunksize_mask) & ~chunksize_mask)
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#endif /* JEMALLOC_H_TYPES */
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/******************************************************************************/
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#ifdef JEMALLOC_H_STRUCTS
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#endif /* JEMALLOC_H_STRUCTS */
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/******************************************************************************/
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#ifdef JEMALLOC_H_EXTERNS
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extern size_t opt_lg_chunk;
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extern const char *opt_dss;
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/* Protects stats_chunks; currently not used for any other purpose. */
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extern malloc_mutex_t chunks_mtx;
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/* Chunk statistics. */
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extern chunk_stats_t stats_chunks;
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extern rtree_t chunks_rtree;
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extern size_t chunksize;
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extern size_t chunksize_mask; /* (chunksize - 1). */
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extern size_t chunk_npages;
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void *chunk_alloc_base(size_t size);
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void *chunk_alloc_arena(chunk_alloc_t *chunk_alloc,
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chunk_dalloc_t *chunk_dalloc, unsigned arena_ind, void *new_addr,
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size_t size, size_t alignment, bool *zero);
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void *chunk_alloc_default(void *new_addr, size_t size, size_t alignment,
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bool *zero, unsigned arena_ind);
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void chunk_unmap(void *chunk, size_t size);
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bool chunk_dalloc_default(void *chunk, size_t size, unsigned arena_ind);
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bool chunk_boot(void);
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void chunk_prefork(void);
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void chunk_postfork_parent(void);
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void chunk_postfork_child(void);
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#endif /* JEMALLOC_H_EXTERNS */
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/******************************************************************************/
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#ifdef JEMALLOC_H_INLINES
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#endif /* JEMALLOC_H_INLINES */
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/******************************************************************************/
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#include "jemalloc/internal/chunk_dss.h"
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#include "jemalloc/internal/chunk_mmap.h"
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