Re: [RFC v2 0/5] BPF controlled io_uring

[Jens Axboe <axboe@kernel.dk>]

On 6/6/25 7:57 AM, Pavel Begunkov wrote:
> This series adds io_uring BPF struct_ops, which allows processing
> events and submitting requests from BPF without returning to user.
> There is only one callback for now, it's called from the io_uring
> CQ waiting loop when there is an event to be processed. It also
> has access to waiting parameters like batching and timeouts.
> 
> It's tested with a program that queues a nop request, waits for
> its completion and then queues another request, repeating it N
> times. The baseline to compare with is traditional io_uring
> application doing same without BPF and using 2 requests links,
> with the same total number of requests.
> 
> # ./link 0 100000000
> type 2-LINK, requests to run 100000000
> sec 20, total (ms) 20374
> # ./link 1 100000000
> type BPF, requests to run 100000000
> sec 13, total (ms) 13700
> 
> The BPF version works ~50% faster on a mitigated kernel, while it's
> not even a completely fair comparison as links are restrictive and
> can't always be used. Without links the speedup reaches ~80%.

Nifty! Great to see the BPF side taking shape, I can think of many cool
things we could do with that. Out of curiosity, tested this on my usual
arm64 vm on the laptop:

axboe@m2max-kvm ~/g/l/examples-bpf (bpf) [1]> ./link 0 100000000
type 2-LINK, requests to run 100000000
sec 13, total (ms) 13868

axboe@m2max-kvm ~/g/l/examples-bpf (bpf)> sudo ./link 1 100000000
type BPF, requests to run 100000000
sec 4, total (ms) 4929

No mitigations or anything configured in this kernel.

I'll take a closer look at the patches.

-- 
Jens Axboe