linux-kernel - Re: [PATCH 0/8] Various io_uring micro-optimizations (reducing lock contention)

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Message-ID: <CAKPOu+-GgXRj-O9K1vdGezTUGZS64w5vpkZg2MM-96vmwqGEnA@mail.gmail.com>
Date: Wed, 29 Jan 2025 19:01:45 +0100
From: Max Kellermann <max.kellermann@...os.com>
To: Jens Axboe <axboe@...nel.dk>
Cc: asml.silence@...il.com, io-uring@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/8] Various io_uring micro-optimizations (reducing lock contention)

On Wed, Jan 29, 2025 at 6:45 PM Jens Axboe <axboe@...nel.dk> wrote:
> Why are you combining it with epoll in the first place? It's a lot more
> efficient to wait on a/multiple events in io_uring_enter() rather than
> go back to a serialize one-event-per-notification by using epoll to wait
> on completions on the io_uring side.

Yes, I wish I could do that, but that works only if everything is
io_uring - all or nothing. Most of the code is built around an
epoll-based loop and will not be ported to io_uring so quickly.

Maybe what's missing is epoll_wait as io_uring opcode. Then I could
wrap it the other way. Or am I supposed to use io_uring
poll_add_multishot for that?

Max