In malloc, why use brk at all? Why not just use mmap?

Calling mmap(2) once per memory allocation is not a viable approach for a general purpose memory allocator because the allocation granularity (the smallest individual unit which may be allocated at a time) for mmap(2) is PAGESIZE (usually 4096 bytes), and because it requires a slow and complicated syscall. The allocator fast path for small allocations … Read more

What does the brk() system call do?

In the diagram you posted, the “break”—the address manipulated by brk and sbrk—is the dotted line at the top of the heap. The documentation you’ve read describes this as the end of the “data segment” because in traditional (pre-shared-libraries, pre-mmap) Unix the data segment was continuous with the heap; before program start, the kernel would … Read more

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)