Re: [PATCH 5/5] io_uring: leverage completion cache for poll requests

[Pavel Begunkov <asml.silence@gmail.com>]

On 9/18/21 7:11 AM, Hao Xu wrote:
> 在 2021/9/18 上午4:39, Pavel Begunkov 写道:
>> On 9/17/21 8:38 PM, Hao Xu wrote:
>>> Leverage completion cache to handle completions of poll requests in a
>>> batch.
>>> Good thing is we save compl_nr - 1 completion_lock and
>>> io_cqring_ev_posted.
>>> Bad thing is compl_nr extra ifs in flush_completion.
>>
>> It does something really wrong breaking all abstractions, we can't go
>> with this. Can we have one of those below?
>> - __io_req_complete(issue_flags), forwarding issue_flags from above
>> - or maybe io_req_task_complete(), if we're in tw
> Make sense. we may need to remove io_clean_op logic in

> io_req_complete_state(), multishot reqs shouldn't do it, and it's ok for
> normal reqs since we do it later in __io_submit_flush_completions->
> io_req_free_batch->io_dismantle_req->io_clean_op, correct me if I'm
> wrong.

req->compl.cflags is in the first 64B, i.e. aliased with req->rw and
others. We need to clean everything left in there before using the
space, that's what io_clean_op() there is for

-- 
Pavel Begunkov