Why malloc+memset is slower than calloc?

Question

It\'s known that calloc is different than malloc in that it initializes the memory allocated. With calloc, the memory is set to zero.

Answer 1

Because on many systems, in spare processing time, the OS goes around setting free memory to zero on its own and marking it safe for calloc(), so when you call calloc(), it may already have free, zeroed memory to give you.