On 06/01/2017 12:57 AM, Victor Stinner wrote:
I would prefer to have an adaptative arena size. For example start at 256 kB and then double the arena size while the memory usage grows. The problem is that pymalloc is currently designed for a fixed arena size. I have no idea how hard it would be to make the size per allocated arena.
It's not hard. The major pain point is that it'd make the address_in_range() inline function slightly more expensive. Currently that code has ARENA_SIZE hardcoded inside it; if the size was dynamic we'd have to look up the size of the arena every time. This function is called every time we free a pointer, so it's done hundreds of thousands of times per second (as you point out).
It's worth trying the experiment to see if dynamic arena sizes would make programs notably faster. However... why not both? Changing to 4mb arenas now is a one-line change, and on first examination seems mostly harmless, and yields an easy (if tiny) performance win. If someone wants to experiment with dynamic arenas, they could go right ahead, and if it works well we could merge that too.
//arry/
_______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
