Mastering Rust - Second Edition

Memory alignment

This is one of those aspects of memory management that you will rarely have to care about unless performance is a strict requirement. Due to data access latency between memory and the processor, when the processor accesses data from memory, it does so in a chunk and not byte by byte. This is to help reduce the number of memory accesses. This chunk size is called the memory access granularity of the CPU. Usually, the chunk sizes are one word (32 bit), two word, four word, and so on, and they depend on the target architecture. Due to this access granularity, it is desired that the data resides in memory which is aligned to a multiple of the word size. If that is not the case, then the CPU has to read and then perform left or ...