Re: [PATCH liburing] test/io_uring_passthrough: add test for vectored fixed-buffers

[Jens Axboe <axboe@kernel.dk>]

On 5/21/25 4:35 AM, Anuj gupta wrote:
>> LGTM, it's great to have the test, thanks Anuj. FWIW, that's the
>> same way I tested the kernel patch.
>>
>> Somewhat unrelated questions, is there some particular reason why all
>> vectored versions are limited to 1 entry iovec? And why do we even care
>> calling io_uring_prep_read/write*() helpers when non of the rw related
>> fields set are used by passthrough? i.e. iovec passed in the second half
>> of the sqe.
> 
> Thanks, Pavel!
> 
> Regarding the vectored I/O being limited to 1 iovec ? yeah, I kept it
> simple initially because the plumbing was easier that way. It?s the same
> in test/read-write.c, where vectored calls also use just one iovec. But
> I agree, for better coverage, it makes sense to test with multiple
> iovecs. I?ll prepare and post a follow-up patch that adds that.

We really should ensure it exercises at least the three common types
for iovec imports:

1) Single segment
2) Multi segment, but below dynamic alloc range
3) Multi segment, above (or equal) to dynamic alloc range

These days 2+3 are the same thing, so makes it a bit easier, as we
just embed a single vec.

Bonus points if you want to send followup patches for both the
passthrough and read-write case using eg 4 segments or something
like that.

-- 
Jens Axboe