[Tim] >> While I would like to increase the pool size, it's fraught with >> danger.
[Antoine Pitrou <solip...@pitrou.net>] > What would be the point of increasing the pool size? Apart from being > able to allocate 4KB objects out of it, I mean. > > Since 4KB+ objects are relatively uncommon (I mean we don't allocate > hundreds of thousands of them per second), I don't think it's really > worthwhile trying to have the small object allocator handle them. I don't care about "large" objects here. It's educated intuition about speed: so long as pymalloc is working within a pool, it's blazing fast. When it has to muck with a new pool, much slower (compared to staying within a pool) code is required. When it has to muck with a new arena, slower still. So the intuition is simple: the larger a pool, the more object operations it can handle staying within its best-case (fastest) code paths. >> It would be nice to find a different way for pymalloc to figure out >> which addresses belong to it. The excruciating Py_ADDRESS_IN_RANGE >> manages to do it in small constant (independent of the number of >> arenas and pools in use) time, which is its only virtue ;-) > So, to sum it up, it's excruciating but fast and works reliably. Why > change it? To enable using pools larger than the greatest common divisor of all OS's native pool sizes. There's also that Py_ADDRESS_IN_RANGE is responsible for countless hours of head-scratching by poor developers trying to use magical memory debuggers - it's at best unusual for code to read up memory without caring a bit whether the memory has ever been stored to. I should note that Py_ADDRESS_IN_RANGE is my code - this isn't a backhanded swipe at someone else. It's always been near the top of the "code stink" scale. So I thought I'd mention it in case someone has been sitting on a cleaner idea but has held back because they didn't want to offend me ;-) _______________________________________________ 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
