1 #define JEMALLOC_CHUNK_MMAP_C_
2 #include "jemalloc/internal/jemalloc_internal.h"
4 /******************************************************************************/
7 chunk_alloc_mmap_slow(size_t size, size_t alignment, bool *zero, bool *commit)
12 alloc_size = size + alignment - PAGE;
13 /* Beware size_t wrap-around. */
14 if (alloc_size < size)
19 pages = pages_map(NULL, alloc_size);
22 leadsize = ALIGNMENT_CEILING((uintptr_t)pages, alignment) -
24 ret = pages_trim(pages, alloc_size, leadsize, size);
25 } while (ret == NULL);
30 *commit = pages_decommit(ret, size);
35 chunk_alloc_mmap(size_t size, size_t alignment, bool *zero, bool *commit)
41 * Ideally, there would be a way to specify alignment to mmap() (like
42 * NetBSD has), but in the absence of such a feature, we have to work
43 * hard to efficiently create aligned mappings. The reliable, but
44 * slow method is to create a mapping that is over-sized, then trim the
45 * excess. However, that always results in one or two calls to
48 * Optimistically try mapping precisely the right amount before falling
49 * back to the slow method, with the expectation that the optimistic
50 * approach works most of the time.
53 assert(alignment != 0);
54 assert((alignment & chunksize_mask) == 0);
56 ret = pages_map(NULL, size);
59 offset = ALIGNMENT_ADDR2OFFSET(ret, alignment);
61 pages_unmap(ret, size);
62 return (chunk_alloc_mmap_slow(size, alignment, zero, commit));
68 *commit = pages_decommit(ret, size);
73 chunk_dalloc_mmap(void *chunk, size_t size)
77 pages_unmap(chunk, size);
79 return (!config_munmap);