cosmopolitan/third_party/dlmalloc/malloc_trim.c

32 lines
1.2 KiB
C

#include "libc/mem/mem.h"
#include "third_party/dlmalloc/dlmalloc.h"
/**
* If possible, gives memory back to the system (via negative arguments
* to sbrk) if there is unused memory at the `high' end of the malloc
* pool or in unused MMAP segments. You can call this after freeing
* large blocks of memory to potentially reduce the system-level memory
* requirements of a program. However, it cannot guarantee to reduce
* memory. Under some allocation patterns, some large free blocks of
* memory will be locked between two used chunks, so they cannot be
* given back to the system.
*
* The `pad' argument to malloc_trim represents the amount of free
* trailing space to leave untrimmed. If this argument is zero, only the
* minimum amount of memory to maintain internal data structures will be
* left. Non-zero arguments can be supplied to maintain enough trailing
* space to service future expected allocations without having to
* re-obtain memory from the system.
*
* @return 1 if it actually released any memory, else 0
*/
int dlmalloc_trim(size_t pad) {
int result = 0;
ensure_initialization();
if (!PREACTION(g_dlmalloc)) {
result = dlmalloc_sys_trim(g_dlmalloc, pad);
POSTACTION(g_dlmalloc);
}
return result;
}