Re: [PATCHSET 0/2] Add support for IORING_CQE_F_SOCK_FULL

[Jens Axboe <axboe@kernel.dk>]

On 11/6/25 5:19 AM, Pavel Begunkov wrote:
> On 11/5/25 19:30, Jens Axboe wrote:
>> Hi,
>>
>> It can be useful for userspace to know if a send request had to go
>> through poll to complete, as that generally means that the socket was
>> out of space. On the send side, this is pretty trivial to support - we
>> just need to check if the request needed to go through poll to complete.
>>
>> This reuses the IORING_CQE_F_SOCK_NONEMPTY flag value, which is only
>> valid for recv operations. As IORING_CQE_F_SOCK_FULL only applies on
>> sends, there's no need for separate values for this flag.
>>
>> Based on an earlier patchset, which utilized REQ_F_POLL_ARMED instead
>> and handled patch 1 a bit differently.
> 
> FWIW, same comments as last time. REQ_F_POLL_TRIGGERED is set not
> in the right place. And, with how tcp manages wait queues, you won't
> be able to use it well for any throttling, as the user will get the
> flagged CQE long time after, when the queue is already half empty.

I'll take a closer look when I'm back, on the road until Monday...

-- 
Jens Axboe