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)
10 size_t alloc_size, leadsize;
12 alloc_size = size + alignment - PAGE;
13 /* Beware size_t wrap-around. */
14 if (alloc_size < size)
17 pages = pages_map(NULL, alloc_size);
20 leadsize = ALIGNMENT_CEILING((uintptr_t)pages, alignment) -
22 ret = pages_trim(pages, alloc_size, leadsize, size);
23 } while (ret == NULL);
28 *commit = pages_decommit(ret, size);
33 chunk_alloc_mmap(size_t size, size_t alignment, bool *zero, bool *commit)
39 * Ideally, there would be a way to specify alignment to mmap() (like
40 * NetBSD has), but in the absence of such a feature, we have to work
41 * hard to efficiently create aligned mappings. The reliable, but
42 * slow method is to create a mapping that is over-sized, then trim the
43 * excess. However, that always results in one or two calls to
46 * Optimistically try mapping precisely the right amount before falling
47 * back to the slow method, with the expectation that the optimistic
48 * approach works most of the time.
51 assert(alignment != 0);
52 assert((alignment & chunksize_mask) == 0);
54 ret = pages_map(NULL, size);
57 offset = ALIGNMENT_ADDR2OFFSET(ret, alignment);
59 pages_unmap(ret, size);
60 return (chunk_alloc_mmap_slow(size, alignment, zero, commit));
66 *commit = pages_decommit(ret, size);
71 chunk_dalloc_mmap(void *chunk, size_t size)
75 pages_unmap(chunk, size);
77 return (!config_munmap);