Yes, io_uring is significantly faster than epoll (I think I had like 20% faster req/s with io_uring.) The catch is that its kernel opt-in and disabled just about everywhere for security reasons. I think that it has direct memory sharing between the kernel and user-land which is kind of yikes. There's been multiple exploits that hit io_uring in recent times. It's because of this that even engineering projects that try to reach the highest performance possible (like Go) don't really bake io_uring in as a sane default. Though if you want to take the risk you can always run it yourself for your favourite language. It is faster but the cost is possible exploits.

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Asmod4n an hour ago | parent | next [-]

The main reason why it gets disabled is fixed now, the latest RC got cBPF support and as such you can restrict what OPs can be run now instead of just fully disabling it.

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Cloudef 3 hours ago | parent | prev | next [-]

Quite depends, I had times when my posix emulation of io_uring (with poll, not epoll) was faster than io_uring. For large zero-copy buffers, io_uring is king however. Also io_uring is useful even for non asynchronous IO as it can implement chain of operations as single atomic operation (mkdir + open it for example).

For something like networking, if you are maximizing packets per second, you'll hit kernel limits[1] very quickly and instead have to start leveraging features like GSO/GRO or completely bypass the network stack.

1: https://github.com/axboe/liburing/discussions/1346

	▲	lukeh 2 hours ago \| parent [-]
		Also it’s nice for things like SPI which have no user space non-blocking API.

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csdreamer7 5 hours ago | parent | prev | next [-]

RHEL 9 and 10 now fully support io_uring by default. It is very recent, but this covers a lot of corporate Linux installs. Gemini 'said' Ubuntu and SuSE support it as well, but did not provide any links to prove it.

https://access.redhat.com/solutions/4723221

Go should reconsider support. They should have a 'go' at it.

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insanitybit 4 hours ago | parent [-]

It's still seccomp'd off in most environments because io-uring is still a seccomp bypass that doesn't play well with kernel security systems (audit subsystem), even if it weren't also like the #1 or #2 exploit vector for privesc.

	▲	Asmod4n an hour ago \| parent [-]
		That’s solved as of last week, you can use cBPF now to disable functionality.

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omcnoe 5 hours ago | parent | prev | next [-]

For a project like Go, wouldn't it be an option to do one-time iouring feature detection in the runtime startup? Exploits are an issue for the entire OS, not the program choosing to use iouring, yeah?

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happyPersonR 6 hours ago | parent | prev [-]

Any kind of poll mode networking:

Rdma, dpdk, io_uring it’s really kind of up to the user to do the memory isolation

In io_urings case tho, you can’t do much because the rings are in the kernel.

I’m hopeful though that with Llm things will get better.

But it’s just hard problem to solve . Very difficult to do in the kernel itself, and folks don’t really even understand tuning for it.

	▲	kshri24 5 hours ago \| parent [-]
		The ring buffers are in shared memory not kernel private. The ring buffers (submission and completion) are shared between kernel space and user space. User publishes requests via submission queue entries (updates tail of buffer while kernel reads head of the buffer), kernel shifts the submission queue buffer on its end and returns a completion queue event by publishing to completion buffer. User pulls from this buffer (specifically the head, kernel updates tail of buffer) in user space.