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From: Hao Xu <haoxu@linux.alibaba.com>
To: Pavel Begunkov <asml.silence@gmail.com>, Jens Axboe <axboe@kernel.dk>
Cc: io-uring@vger.kernel.org, Joseph Qi <joseph.qi@linux.alibaba.com>
Subject: Re: [PATCH 4/6] io_uring: let fast poll support multishot
Date: Wed, 8 Sep 2021 19:21:23 +0800	[thread overview]
Message-ID: <2ba9fdb5-6d60-21f5-3e20-bc1687c9509f@linux.alibaba.com> (raw)
In-Reply-To: <8c052e2a-0ee6-7dac-1169-9d395d2ecad8@linux.alibaba.com>

在 2021/9/7 下午2:48, Hao Xu 写道:
> 在 2021/9/7 上午3:04, 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.
>>>
>>> Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
>>> ---
>>>   fs/io_uring.c | 15 ++++++++++++---
>>>   1 file changed, 12 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>> index d6df60c4cdb9..dae7044e0c24 100644
>>> --- a/fs/io_uring.c
>>> +++ b/fs/io_uring.c
>>> @@ -5277,8 +5277,15 @@ static void io_async_task_func(struct io_kiocb 
>>> *req, bool *locked)
>>>           return;
>>>       }
>>> -    hash_del(&req->hash_node);
>>> -    io_poll_remove_double(req);
>>> +    if (READ_ONCE(apoll->poll.canceled))
>>> +        apoll->poll.events |= EPOLLONESHOT;
>>> +    if (apoll->poll.events & EPOLLONESHOT) {
>>> +        hash_del(&req->hash_node);
>>> +        io_poll_remove_double(req);
>>> +    } else {
>>> +        add_wait_queue(apoll->poll.head, &apoll->poll.wait);
>>
>> It looks like it does both io_req_task_submit() and adding back
>> to the wq, so io_issue_sqe() may be called in parallel with
>> io_async_task_func(). If so, there will be tons of all kind of
>> races.
> IMHO, io_async_task_func() is called in original context one by
> one(except PF_EXITING is set, it is also called in system-wq), so
> shouldn't be parallel case there.
ping...
>>
>>> +    }
>>> +
>>>       spin_unlock(&ctx->completion_lock);
>>>       if (!READ_ONCE(apoll->poll.canceled))
>>> @@ -5366,7 +5373,7 @@ static int io_arm_poll_handler(struct io_kiocb 
>>> *req)
>>>       struct io_ring_ctx *ctx = req->ctx;
>>>       struct async_poll *apoll;
>>>       struct io_poll_table ipt;
>>> -    __poll_t ret, mask = EPOLLONESHOT | POLLERR | POLLPRI;
>>> +    __poll_t ret, mask = POLLERR | POLLPRI;
>>>       int rw;
>>>       if (!req->file || !file_can_poll(req->file))
>>> @@ -5388,6 +5395,8 @@ static int io_arm_poll_handler(struct io_kiocb 
>>> *req)
>>>           rw = WRITE;
>>>           mask |= POLLOUT | POLLWRNORM;
>>>       }
>>> +    if (!(req->flags & REQ_F_APOLL_MULTISHOT))
>>> +        mask |= EPOLLONESHOT;
>>>       /* if we can't nonblock try, then no point in arming a poll 
>>> handler */
>>>       if (!io_file_supports_nowait(req, rw))
>>>
>>


  reply	other threads:[~2021-09-08 11:21 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-03 11:00 [RFC 0/6] fast poll multishot mode Hao Xu
2021-09-03 11:00 ` [PATCH 1/6] io_uring: enhance flush completion logic Hao Xu
2021-09-03 11:42   ` Pavel Begunkov
2021-09-03 12:08     ` Hao Xu
2021-09-03 12:27       ` Pavel Begunkov
2021-09-03 13:38         ` Hao Xu
2021-09-17 18:49           ` Hao Xu
2021-09-03 11:00 ` [PATCH 2/6] io_uring: add IORING_ACCEPT_MULTISHOT for accept Hao Xu
2021-09-03 11:00 ` [PATCH 3/6] io_uring: add REQ_F_APOLL_MULTISHOT for requests Hao Xu
2021-09-03 11:00 ` [PATCH 4/6] io_uring: let fast poll support multishot Hao Xu
2021-09-06 15:56   ` Pavel Begunkov
2021-09-06 17:40     ` Hao Xu
2021-09-06 19:09       ` Pavel Begunkov
2021-09-07  6:38         ` Hao Xu
2021-09-06 19:04   ` Pavel Begunkov
2021-09-07  6:48     ` Hao Xu
2021-09-08 11:21       ` Hao Xu [this message]
2021-09-08 12:03         ` Pavel Begunkov
2021-09-08 13:13           ` Pavel Begunkov
2021-09-09  7:01           ` Hao Xu
2021-09-09  8:29             ` Hao Xu
2021-09-11 10:49               ` Pavel Begunkov
2021-09-11 20:19                 ` Hao Xu
2021-09-03 11:00 ` [PATCH 5/6] io_uring: implement multishot mode for accept Hao Xu
2021-09-04 22:39   ` Pavel Begunkov
2021-09-04 22:40     ` Pavel Begunkov
2021-09-06 15:34       ` Pavel Begunkov
2021-09-03 11:00 ` [PATCH 6/6] io_uring: enable " Hao Xu
2021-09-03 16:29   ` Jens Axboe
2021-09-04 15:34     ` Hao Xu
2021-09-04 18:40       ` Jens Axboe
2021-09-04 22:46         ` Pavel Begunkov
2021-09-05  7:29           ` Hao Xu
2021-09-05 19:44           ` Jens Axboe
2021-09-06  8:26             ` Hao Xu
2021-09-06  8:28               ` Hao Xu
2021-09-06 13:24               ` Jens Axboe
2021-09-06 12:35             ` Hao Xu
2021-09-06 13:31               ` Jens Axboe
2021-09-06 15:00                 ` Hao Xu
2021-09-06 15:32               ` Pavel Begunkov
2021-09-06 16:42                 ` Jens Axboe
2021-09-04 22:43   ` Pavel Begunkov
2021-09-05  6:25     ` Hao Xu
2021-09-05  8:27       ` Pavel Begunkov
2021-09-03 11:02 ` [RFC 0/6] fast poll multishot mode Hao Xu

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