140 lines
3.5 KiB
C
140 lines
3.5 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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/* Arena from which this extent came, or UINT_MAX if unassociated. */
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unsigned e_arena_ind;
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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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/*
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* Usable size class index for allocations residing in this extent,
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* regardless of whether the extent is a slab. Extent size and usable
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* size often differ even for non-slabs, either due to large_pad or
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* promotion of sampled small regions.
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*/
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szind_t e_szind;
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/*
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* Serial number (potentially non-unique).
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*
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* In principle serial numbers can wrap around on 32-bit systems if
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* JEMALLOC_MUNMAP is defined, but as long as comparison functions fall
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* back on address comparison for equal serial numbers, stable (if
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* imperfect) ordering is maintained.
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*
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* Serial numbers may not be unique even in the absence of wrap-around,
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* e.g. when splitting an extent and assigning the same serial number to
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* both resulting adjacent extents.
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*/
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size_t e_sn;
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/* Extent state. */
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extent_state_t e_state;
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/*
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* The zeroed flag is used by extent recycling code to track whether
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* memory is zero-filled.
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*/
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bool e_zeroed;
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/*
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* True if physical memory is committed to the extent, whether
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* explicitly or implicitly as on a system that overcommits and
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* satisfies physical memory needs on demand via soft page faults.
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*/
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bool e_committed;
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/*
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* The slab flag indicates whether the extent is used for a slab of
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* small regions. This helps differentiate small size classes, and it
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* indicates whether interior pointers can be looked up via iealloc().
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*/
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bool e_slab;
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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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