linux-kernel - Re: [PATCH v3 0/4] fast poll multishot mode

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Message-ID: <390a7780-b02b-b086-803c-a8540abfd436@gmail.com>
Date:   Sun, 8 May 2022 00:05:08 +0800
From:   Hao Xu <haoxu.linux@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org
Cc:     Pavel Begunkov <asml.silence@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/4] fast poll multishot mode

在 2022/5/7 下午11:28, Jens Axboe 写道:
> On 5/7/22 8:06 AM, Hao Xu wrote:
>> Let multishot support multishot mode, currently only add accept as its
>> first comsumer.
> 
> consumer
> 
>> theoretical analysis:
>>    1) when connections come in fast
>>      - singleshot:
>>                add accept sqe(userpsace) --> accept inline
> 
> userspace
> 
>>                                ^                 |
>>                                |-----------------|
>>      - multishot:
>>               add accept sqe(userspace) --> accept inline
>>                                                ^     |
>>                                                |--*--|
>>
>>      we do accept repeatedly in * place until get EAGAIN
>>
>>    2) when connections come in at a low pressure
>>      similar thing like 1), we reduce a lot of userspace-kernel context
>>      switch and useless vfs_poll()
> 
> Overall this looks better than v2 for sure, just some minor tweaks
> needed I believe.
> 
> But we still need to consider direct accept with multishot... Should
> probably be an add-on patch as I think it'd get a bit more complicated
> if we need to be able to cheaply find an available free fixed fd slot.
> I'll try and play with that.

I'm tending to use a new mail account to send v4 rather than the gmail
account since the git issue seems to be network related.
I'll also think about the fixed fd problem.

Thanks,
Hao

>