Re: [PATCH 11/11] io_uring: get rid of intermediate aux cqe caches

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On 3/15/24 10:23 AM, Pavel Begunkov wrote:
> On 3/15/24 16:20, Jens Axboe wrote:
>> On 3/15/24 9:30 AM, Pavel Begunkov wrote:
>>> io_post_aux_cqe(), which is used for multishot requests, delays
>>> completions by putting CQEs into a temporary array for the purpose
>>> completion lock/flush batching.
>>>
>>> DEFER_TASKRUN doesn't need any locking, so for it we can put completions
>>> directly into the CQ and defer post completion handling with a flag.
>>> That leaves !DEFER_TASKRUN, which is not that interesting / hot for
>>> multishot requests, so have conditional locking with deferred flush
>>> for them.
>>
>> This breaks the read-mshot test case, looking into what is going on
>> there.
> 
> I forgot to mention, yes it does, the test makes odd assumptions about
> overflows, IIRC it expects that the kernel allows one and only one aux
> CQE to be overflown. Let me double check

Yeah this is very possible, the overflow checking could be broken in
there. I'll poke at it and report back.

-- 
Jens Axboe





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