165 lines
4.7 KiB
C
165 lines
4.7 KiB
C
#ifndef JEMALLOC_INTERNAL_EXTENT_STRUCTS_H
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#define JEMALLOC_INTERNAL_EXTENT_STRUCTS_H
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typedef enum {
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extent_state_active = 0,
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extent_state_dirty = 1,
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extent_state_muzzy = 2,
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extent_state_retained = 3
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} extent_state_t;
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/* Extent (span of pages). Use accessor functions for e_* fields. */
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struct extent_s {
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/*
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* Bitfield containing several fields:
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*
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* a: arena_ind
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* b: slab
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* c: committed
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* z: zeroed
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* t: state
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* i: szind
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* n: sn
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*
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* nnnnnnnn ... nnnnnnni iiiiiiit tzcbaaaa aaaaaaaa
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*
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* arena_ind: Arena from which this extent came, or all 1 bits if
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* unassociated.
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*
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* slab: The slab flag indicates whether the extent is used for a slab
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* of small regions. This helps differentiate small size classes,
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* and it indicates whether interior pointers can be looked up via
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* iealloc().
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*
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* committed: The committed flag indicates whether physical memory is
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* committed to the extent, whether explicitly or implicitly
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* as on a system that overcommits and satisfies physical
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* memory needs on demand via soft page faults.
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*
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* zeroed: The zeroed flag is used by extent recycling code to track
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* whether memory is zero-filled.
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*
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* state: The state flag is an extent_state_t.
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*
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* szind: The szind flag indicates usable size class index for
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* allocations residing in this extent, regardless of whether the
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* extent is a slab. Extent size and usable size often differ
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* even for non-slabs, either due to large_pad or promotion of
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* sampled small regions.
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*
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* sn: Serial number (potentially non-unique).
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*
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* Serial numbers may wrap around if JEMALLOC_MUNMAP is defined, but
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* as long as comparison functions fall back on address comparison
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* for equal serial numbers, stable (if imperfect) ordering is
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* maintained.
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*
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* Serial numbers may not be unique even in the absence of
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* wrap-around, e.g. when splitting an extent and assigning the same
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* serial number to both resulting adjacent extents.
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*/
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uint64_t e_bits;
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#define EXTENT_BITS_ARENA_SHIFT 0
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#define EXTENT_BITS_ARENA_MASK \
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(((1U << MALLOCX_ARENA_BITS) - 1) << EXTENT_BITS_ARENA_SHIFT)
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#define EXTENT_BITS_SLAB_SHIFT MALLOCX_ARENA_BITS
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#define EXTENT_BITS_SLAB_MASK (0x1U << EXTENT_BITS_SLAB_SHIFT)
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#define EXTENT_BITS_COMMITTED_SHIFT (MALLOCX_ARENA_BITS + 1)
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#define EXTENT_BITS_COMMITTED_MASK (0x1U << EXTENT_BITS_COMMITTED_SHIFT)
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#define EXTENT_BITS_ZEROED_SHIFT (MALLOCX_ARENA_BITS + 2)
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#define EXTENT_BITS_ZEROED_MASK (0x1U << EXTENT_BITS_ZEROED_SHIFT)
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#define EXTENT_BITS_STATE_SHIFT (MALLOCX_ARENA_BITS + 3)
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#define EXTENT_BITS_STATE_MASK (0x3U << EXTENT_BITS_STATE_SHIFT)
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#define EXTENT_BITS_SZIND_SHIFT (MALLOCX_ARENA_BITS + 5)
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#define EXTENT_BITS_SZIND_MASK \
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(((1U << LG_CEIL_NSIZES) - 1) << EXTENT_BITS_SZIND_SHIFT)
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#define EXTENT_BITS_SN_SHIFT \
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(MALLOCX_ARENA_BITS + 5 + LG_CEIL_NSIZES)
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#define EXTENT_BITS_SN_MASK (UINT64_MAX << EXTENT_BITS_SN_SHIFT)
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/* Pointer to the extent that this structure is responsible for. */
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void *e_addr;
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/* Extent size. */
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size_t e_size;
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union {
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/* Small region slab metadata. */
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arena_slab_data_t e_slab_data;
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/* Profile counters, used for large objects. */
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union {
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void *e_prof_tctx_pun;
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prof_tctx_t *e_prof_tctx;
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};
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};
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/*
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* List linkage, used by a variety of lists:
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* - arena_bin_t's slabs_full
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* - extents_t's LRU
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* - stashed dirty extents
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* - arena's large allocations
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* - arena's extent structure freelist
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*/
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ql_elm(extent_t) ql_link;
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/* Linkage for per size class sn/address-ordered heaps. */
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phn(extent_t) ph_link;
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};
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typedef ql_head(extent_t) extent_list_t;
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typedef ph(extent_t) extent_heap_t;
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/* Quantized collection of extents, with built-in LRU queue. */
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struct extents_s {
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malloc_mutex_t mtx;
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/*
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* Quantized per size class heaps of extents.
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*
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* Synchronization: mtx.
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*/
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extent_heap_t heaps[NPSIZES+1];
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/*
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* Bitmap for which set bits correspond to non-empty heaps.
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*
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* Synchronization: mtx.
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*/
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bitmap_t bitmap[BITMAP_GROUPS(NPSIZES+1)];
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/*
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* LRU of all extents in heaps.
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*
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* Synchronization: mtx.
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*/
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extent_list_t lru;
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/*
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* Page sum for all extents in heaps.
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*
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* The synchronization here is a little tricky. Modifications to npages
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* must hold mtx, but reads need not (though, a reader who sees npages
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* without holding the mutex can't assume anything about the rest of the
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* state of the extents_t).
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*/
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atomic_zu_t npages;
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/* All stored extents must be in the same state. */
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extent_state_t state;
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/*
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* If true, delay coalescing until eviction; otherwise coalesce during
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* deallocation.
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*/
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bool delay_coalesce;
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};
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#endif /* JEMALLOC_INTERNAL_EXTENT_STRUCTS_H */
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