CPU access data alignment is also crucial for efficiently mapping memory through a hardware address translation mechanism. Modern operating systems operate 4 KB memory blocks or pages to map a process' virtual address space to physical memory. Aligning data structures on 4 KB boundaries can lead to performance gains.

The same technique we described in this recipe can be applied to align data to the memory page boundaries. Note, however, that posix_memalign may require twice as much memory than what was requested to fulfill this request. This memory overhead growth may be significant for larger alignment blocks.