Re: Sending CQE to a different ring

[Jens Axboe <axboe@kernel.dk>]

On 3/10/22 8:43 AM, Jens Axboe wrote:
> On 3/10/22 8:36 AM, Artyom Pavlov wrote:
>> After thinking about it a bit, I think this approach has one serious
>> disadvantage: you lose successful result value of the initial request.
>> Imagine we submit IORING_OP_READ and link IORING_OP_WAKEUP_RING to it.
>> If the request is completed successfully, both ring1 and ring2 will
>> lose number of read bytes.
> 
> But you know what the result is, otherwise you would've gotten a cqe
> posted if it wasn't what you asked for.

Can also be made more explicit by setting sqe->len to what you set the
original request length to, and then pass that back in the cqe->res
instead of using the pid from the task that sent it. Then you'd have it
immediately available. Might make more sense than the pid, not sure
anyone would care about that?

-- 
Jens Axboe