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

[Hao Xu <haoxu@linux.alibaba.com>]

在 2021/9/19 下午8:04, Pavel Begunkov 写道:
> 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
True, and that's why we souldn't do it for multishot reqs, since they
are not completed yet, and we won't reuse the req resource until its
final completion.
>