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#define JEMALLOC_CHUNK_MMAP_C_
#include "jemalloc/internal/jemalloc_internal.h"
/******************************************************************************/
static void *
chunk_alloc_mmap_slow(size_t size, size_t alignment, bool *zero, bool *commit)
{
void *ret;
size_t alloc_size;
alloc_size = size + alignment - PAGE;
/* Beware size_t wrap-around. */
if (alloc_size < size)
return (NULL);
do {
void *pages;
size_t leadsize;
pages = pages_map(NULL, alloc_size);
if (pages == NULL)
return (NULL);
leadsize = ALIGNMENT_CEILING((uintptr_t)pages, alignment) -
(uintptr_t)pages;
ret = pages_trim(pages, alloc_size, leadsize, size);
} while (ret == NULL);
assert(ret != NULL);
*zero = true;
if (!*commit)
*commit = pages_decommit(ret, size);
return (ret);
}
void *
chunk_alloc_mmap(size_t size, size_t alignment, bool *zero, bool *commit)
{
void *ret;
size_t offset;
/*
* Ideally, there would be a way to specify alignment to mmap() (like
* NetBSD has), but in the absence of such a feature, we have to work
* hard to efficiently create aligned mappings. The reliable, but
* slow method is to create a mapping that is over-sized, then trim the
* excess. However, that always results in one or two calls to
* pages_unmap().
*
* Optimistically try mapping precisely the right amount before falling
* back to the slow method, with the expectation that the optimistic
* approach works most of the time.
*/
assert(alignment != 0);
assert((alignment & chunksize_mask) == 0);
ret = pages_map(NULL, size);
if (ret == NULL)
return (NULL);
offset = ALIGNMENT_ADDR2OFFSET(ret, alignment);
if (offset != 0) {
pages_unmap(ret, size);
return (chunk_alloc_mmap_slow(size, alignment, zero, commit));
}
assert(ret != NULL);
*zero = true;
if (!*commit)
*commit = pages_decommit(ret, size);
return (ret);
}
bool
chunk_dalloc_mmap(void *chunk, size_t size)
{
if (config_munmap)
pages_unmap(chunk, size);
return (!config_munmap);
}
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