True, but zones and HeapAlloc do a fair bit of work to handle objects of multiple sizes. If you're partitioning up a page and you know every object on the page is 8 or 16 or 48 bytes, it's MUCH simpler. And a lot of the data structures in a compiler tend to be small-tens-of-bytes nodes.
On 8/17/20, Jim Geist <velocityboy@gmail.com> wrote:
> When did mmap(2) come about? Another thing I've seen is building a small
> block allocator on top of that. You can guarantee that all your objects are
> nicely collected into the same set of pages for locality with very little
> overhead.
>
mmap(2) certainly can be used to allocate blocks for the mini-heap
itself, but you still have to write your own equivalents of malloc()
and free() to allocate data structures within the mini-heap. The nice
thing about VMS heap zones and Microsoft's private heaps is that you
get the malloc()/free() layer off-the-shelf; you don't have to roll
your own.
-Paul W.