// malloc/malloc.h
struct mallinfo
{
int arena; /* non-mmapped space allocated from system */
int ordblks; /* number of free chunks */
int smblks; /* number of fastbin blocks */
int hblks; /* number of mmapped regions */
int hblkhd; /* space in mmapped regions */
int usmblks; /* always 0, preserved for backwards compatibility */
int fsmblks; /* space available in freed fastbin blocks */
int uordblks; /* total allocated space */
int fordblks; /* total free space */
int keepcost; /* top-most, releasable (via malloc_trim) space */
};
