On 04/10/2014 02:02, Steven D'Aprano wrote:
Way back in the mid 1980s, Apple Macintoshes used a memory manager which could move memory around.
But the memory manager didn't return a pointer to memory the way malloc does. It returned a pointer to the pointer and you had to double dereference it to get the heap address (ISTR, 30 years ago now). The advantage being the memory manager could shuffle the memory about and update the pointers. Your pointer to a pointer would still point to the same block after a shuffle. Of course you couldn't hold on to a partial dereference across system calls... can you guess why? :-)
Linux has (had) a allocation scheme where blocks came from different sized areas depending on the size requested. So all requests below 4k came from one heap area, and so on for 16k, 64k 256k, 1M etc. Meaning that code requesting a freeing up small amounts fragged the small allocation zone and so a big allocation would die due to fragmentation of small amounts. That was in kernel 2.4 days, sorry I'm off the bleeding edge now with how the allocator works in modern kernels.
Andy -- https://mail.python.org/mailman/listinfo/python-list
