New submission from Tim Peters <t...@python.org>:
On 64-bit Python, many object sizes essentially doubled over 32-bit Python, because Python objects are so heavy with pointers. More recently, forcing alignment to 16 bytes on 64-bit boxes boosted the memory requirements more modestly. But obmalloc's 256 KiB arenas and 4 KiB pools haven't changed since obmalloc was first written, and its `address_in_range()` machinery cannot deal with pools bigger than that (they're segfault factories, because the machinery relies on that a pool is no larger than a system page). obmalloc's fastest paths are those that stay within a pool. Whenever a pool boundary is hit, it necessarily gets slower, then slower still if an arena boundary is hit. So I propose to: - Remove the 4 KiB pool limit, by making `address_in_range()` page-based rather than pool-based. Pools should be able to span any power-of-2 number of pages. Then a pool for a given size class will be able to hold that many more times as many objects too, and so stay in the fastest paths more often. - On 64-bit boxes, increase both POOL_SIZE and ARENA_SIZE. ---------- components: Interpreter Core messages: 345097 nosy: tim.peters priority: normal severity: normal status: open title: obmalloc: eliminate limit on pool size type: enhancement versions: Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue37211> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
