A neat trick I found for reusing physical memory

to it (this is what will be dup'd later):

memset(template, 67, SIZE);

now, to allocate a chunk of memory with this template, use mmap with MAP_PRIVATE:

char *copy = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);

this is cool because regardless of the size of the initial allocation, the copy isn't taking up any physical memory. and say you mutate the copy now:

copy[i] = 69;

this will only allocate a single page of memory (4 KiB); the rest of the pages are still shared with the original template!

i did a test here where i allocated 32 MiB, and then