On 9/6/21 6:40 PM, Hao Xu wrote:
> 在 2021/9/6 下午11:56, Pavel Begunkov 写道:
>> On 9/3/21 12:00 PM, Hao Xu wrote:
>>> For operations like accept, multishot is a useful feature, since we can
>>> reduce a number of accept sqe. Let's integrate it to fast poll, it may
>>> be good for other operations in the future.
>>
>> __io_arm_poll_handler() |
>> -> vfs_poll() |
>> | io_async_task_func() // post CQE
>> | ...
>> | do_apoll_rewait();
>> -> continues after vfs_poll(),|
>> removing poll->head of |
>> the second poll attempt. |
>>
>>
> Sorry.. a little bit confused by this case, would you mind explain a bit
> more..is the right part a system-workqueue context? and is
> do_apoll_rewait() io_poll_rewait() function?
I meant in a broad sense. If your patches make lifetime of an accept
request to be like:
accept() -> arm_apoll() -> apoll_func() -> accept() -> ...
-> ... (repeat many times)
then do_apoll_rewait() is the second accept in the scheme.
If not, and it's
accept() -> arm_poll() -> apoll_func() -> apoll_func() ->
... -> ?
Then that "do_apoll_rewait()" should have been second and
other apoll_func()s.
So, it's rather a thing to look after, but not a particular
bug.
>> One of the reasons for forbidding multiple apoll's is that it
>> might be racy. I haven't looked into this implementation, but
>> we should check if there will be problems from that.
>>
>> FWIW, putting aside this patchset, the poll/apoll is not in
>> the best shape and can use some refactoring.
>>
>>
[...]
--
Pavel Begunkov
