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Axboe Achieves 8M IOPS Per-Core with Newest Linux Optimization Patches

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31–40 of 53 posts

Re: Axboe Achieves 8M IOPS Per-Core with Newest Linux Optimization Patches

#31
post #7

I know this will be down voted but I've learned to be a bit skeptical of Axboe's monumental claims. There have been some unfair benchmarks posted in the past surrounding io_uring that were called out by people on the liburing repositories. Take these with a grain of salt - his results are notoriously very difficult to reproduce, even on identical hardware. Nevertheless, io_uring is certainly the better design and I'm…

Not disagreeing with you, but even if benchmarks are unfair, these reports are still a good illustration of progress. Unless there are some drawbacks to these optimizations, there should be no negative side-effects. AFAIK as I know, these changes shouldn't negatively impact tasks that are not making any use of these features. So, even if improvements are not directly proportional to what is being reported, they're st…

> Unless there are some drawbacks to these optimizations, there should be no negative side-effects.

Historically the benchmarks have been crafted in a way to make them seem faster than their real-world and well-formed opponents (e.g. the io_uring vs epoll benchmark). One issue that was pointed out was that the io_uring benchmark eschewed proper error handling in order to avoid some branches, whereas the epoll benchmark properly error checked. This reduced the benchmark times considerably, though no correction was ever published after the fact.

This is why in the Github issue I mentioned in another comment there are some people understandably a bit annoyed. I don't choose to jump to conclusions about Axboe's intent, and my original comment wasn't meant to do so.

Re: Axboe Achieves 8M IOPS Per-Core with Newest Linux Optimization Patches

#33
post #29
post #16

Earlier quoted context omitted.

> There have been some unfair benchmarks posted in the past surrounding io_uring that were called out by people on the liburing repositories. Could you provide any links to these discussions?

Sure. https://github.com/axboe/liburing/issues/189 Original claims were in the 90% and above performance increase over epoll. Then issues were found, and the figure was adjusted to 60% over epoll. Then more issues were found, and now real-world performance tests are showing minimal speedups if any. Unfortunately the sibling commentors don't see "computer science" as a science but instead as a "feel good hobby", it se…

[deleted]

Re: Axboe Achieves 8M IOPS Per-Core with Newest Linux Optimization Patches

#34
post #29
post #16

Earlier quoted context omitted.

> There have been some unfair benchmarks posted in the past surrounding io_uring that were called out by people on the liburing repositories. Could you provide any links to these discussions?

Sure. https://github.com/axboe/liburing/issues/189 Original claims were in the 90% and above performance increase over epoll. Then issues were found, and the figure was adjusted to 60% over epoll. Then more issues were found, and now real-world performance tests are showing minimal speedups if any. Unfortunately the sibling commentors don't see "computer science" as a science but instead as a "feel good hobby", it se…

But if you read the thread, you realize he is testing on a 2011 laptop, and the older architecture may be causing the issues. He reported a 3x speedup running the benchmark on a Raspberry Pi 4 in the same thread[0]

Someone claimed that you don't get to see the benefit of io_uring in a hypervisor[1], but they did not provide benchmark results.

[0]: https://github.com/axboe/liburing/issues/189#issuecomment-94...

[1]: https://github.com/axboe/liburing/issues/189#issuecomment-73...

Re: Axboe Achieves 8M IOPS Per-Core with Newest Linux Optimization Patches

#35

I keep seeing Axboe as a typo'd version of Adobe and it's really bugging me edit- It's someone's name, I thought it was a company or product

It is a wlel kwnon pohnnomeen taht you can sawp all the ltteers in a wrod and as lnog as the fsrit and lsat is ccrreot it wlil sitll be cibemreplohnse. https://www.mrc-cbu.cam.ac.uk/people/matt.davis/cmabridge/

It's wild that I was able to read that in my head at full speed, with the correct word pronunciation (except the last word... wonder what the upper limit on that is anyway?)

Re: Axboe Achieves 8M IOPS Per-Core with Newest Linux Optimization Patches

#36
post #7

I know this will be down voted but I've learned to be a bit skeptical of Axboe's monumental claims. There have been some unfair benchmarks posted in the past surrounding io_uring that were called out by people on the liburing repositories. Take these with a grain of salt - his results are notoriously very difficult to reproduce, even on identical hardware. Nevertheless, io_uring is certainly the better design and I'm…

Not disagreeing with you, but even if benchmarks are unfair, these reports are still a good illustration of progress. Unless there are some drawbacks to these optimizations, there should be no negative side-effects. AFAIK as I know, these changes shouldn't negatively impact tasks that are not making any use of these features. So, even if improvements are not directly proportional to what is being reported, they're st…

Why wouldn't you report more rigorous benchmarks for typical use cases though? Why can't others reproduce it the same?

Re: Axboe Achieves 8M IOPS Per-Core with Newest Linux Optimization Patches

#38
post #29
post #16

Earlier quoted context omitted.

> There have been some unfair benchmarks posted in the past surrounding io_uring that were called out by people on the liburing repositories. Could you provide any links to these discussions?

Sure. https://github.com/axboe/liburing/issues/189 Original claims were in the 90% and above performance increase over epoll. Then issues were found, and the figure was adjusted to 60% over epoll. Then more issues were found, and now real-world performance tests are showing minimal speedups if any. Unfortunately the sibling commentors don't see "computer science" as a science but instead as a "feel good hobby", it se…

If that's the best example you've got I'm writing your entire comment off as a steaming pile of FUD.

Re: Axboe Achieves 8M IOPS Per-Core with Newest Linux Optimization Patches

#39
post #29
post #16

Earlier quoted context omitted.

> There have been some unfair benchmarks posted in the past surrounding io_uring that were called out by people on the liburing repositories. Could you provide any links to these discussions?

Sure. https://github.com/axboe/liburing/issues/189 Original claims were in the 90% and above performance increase over epoll. Then issues were found, and the figure was adjusted to 60% over epoll. Then more issues were found, and now real-world performance tests are showing minimal speedups if any. Unfortunately the sibling commentors don't see "computer science" as a science but instead as a "feel good hobby", it se…

Why did you omit the response you received from a netty developer that showed a large performance improvement[1]? Focusing entirely on the few cases where people report regressions and ignoring all of the reports of improvements isn't a good way to make an objective assessment.

[1] https://github.com/netty/netty/issues/10622#issuecomment-701...

Re: Axboe Achieves 8M IOPS Per-Core with Newest Linux Optimization Patches

#40
post #27

He just hit 9M https://twitter.com/axboe/status/1450188650852065291

Anyone know exactly how to replicate this? I see the command line, but it looks like t/io_ring is maybe a wrapper around fio? Or maybe a binary/git repo so I can compile my own?
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