Memory Allocator

Level 1 allocator (page allocator)

• Buddy allocator
• Alternative: Bitmap allocator (page size = 64KB, map size = 2KB/GB)
• API:
• void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset);
  • fd == -1, support MAP_PRIVATE | MAP_ANONYMOUS only
  • Always R/W, ignore prot
• int munmap(void *addr, size_t length);
• Dummy:
  • int madvise(void *addr, size_t length, int advice);
  • int mlock(const void *addr, size_t len);
  • int mlockall(int flags);
  • int mprotect(void *addr, size_t len, int prot);
  • int msync(void *addr, size_t length, int flags);
  • int munlock(const void *addr, size_t len);
  • int munlockall(void);

Level 2 allocator

• Slab allocator
• API
• void* malloc(size_t size);
• void free(void *ptr);
• void *memalign(size_t alignment, size_t size);
• int posix_memalign(void **memptr, size_t alignment, size_t size);
• Wrapper:
  • void* calloc(size_t count, size_t size);
  • void* realloc(void *ptr, size_t size);