Re: AIO v2.5
От | Andres Freund |
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Тема | Re: AIO v2.5 |
Дата | |
Msg-id | t2za3i3u7jg4hqcxpr4n6tjuwm2bwpuwva344yfz7tiw3mlim2@ookbzlxmeum6 обсуждение исходный текст |
Ответ на | Re: AIO v2.5 (Noah Misch <noah@leadboat.com>) |
Ответы |
Re: AIO v2.5
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Список | pgsql-hackers |
Hi, On 2025-03-25 12:39:56 -0700, Noah Misch wrote: > On Tue, Mar 25, 2025 at 02:58:37PM -0400, Andres Freund wrote: > > I don't know if that's an intentional or unintentional behavioral difference. > > > > There are 2 1/2 ways around this: > > > > 1) Stop using IOSQE_ASYNC heuristic > > 2a) Wait for all in-flight IOs when any FD gets closed > > 2b) Wait for all in-flight IOs using FD when it gets closed > > > > Given that we have clear evidence that io_uring doesn't completely support > > closing FDs while IOs are in flight, be it a bug or intentional, it seems > > clearly better to go for 2a or 2b. > > Agreed. If a workload spends significant time on fd.c closing files, I > suspect that workload already won't have impressive benchmark numbers. > Performance-seeking workloads will already want to tune FD usage high enough > to keep FDs long-lived. So (1) clearly loses, and neither (2a) nor (2b) > clearly beats the other. I'd try (2b) first but, if complicated, quickly > abandon it in favor of (2a). What other considerations could be important? The only other consideration I can think of is whether this should happen for all io_methods or not. I'm inclined to do it via a bool in IoMethodOps, but I guess one could argue it's a bit weird to have a bool in a struct called *Ops. Greetings, Andres Freund
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