Re: [PATCH] RDMA/rxe: Check the last packet by RXE_END_MASK

[Yanjun Zhu <yanjun.zhu@linux.dev>]

在 2022/1/18 10:20, yangx.jy@fujitsu.com 写道:
> On 2022/1/15 11:38, Yanjun Zhu wrote:
>> 在 2022/1/12 11:58, yangx.jy@fujitsu.com 写道:
>>> On 2022/1/12 9:19, Yanjun Zhu wrote:
>>>> 在 2022/1/11 23:16, Haakon Bugge 写道:
>>>>>> On 11 Jan 2022, at 15:42, Yanjun Zhu <yanjun.zhu@linux.dev> wrote:
>>>>>>
>>>>>>
>>>>>> 在 2022/1/10 13:17, yangx.jy@fujitsu.com 写道:
>>>>>>> On 2022/1/7 19:49, Yanjun Zhu wrote:
>>>>>>>> It seems that it does not mean to check the last packet. It means
>>>>>>>> that
>>>>>>>> it receives a MSN response.
>>>>>>> Hi Yanjun,
>>>>>>>
>>>>>>> Checking the last packet is a way to indicate that responder has
>>>>>>> completed an entire request(including multiple packets) and then
>>>>>>> increases a msn.
>>>>>> Hi, Xiao
>>>>>>
>>>>>> What does the msn mean?
>>>>> Message Sequence Number.
>>>> Thanks, Haakon
>>>>
>>>> I am reading the following from the spec.
>>>>
>>>> "
>>>>
>>>> C9-148: An HCA responder using Reliable Connection service shall
>>>> initialize
>>>>
>>>> its MSN value to zero. The responder shall increment its MSN
>>>> whenever it has successfully completed processing a new, valid request
>>>> message. The MSN shall not be incremented for duplicate requests. The
>>>> incremented MSN shall be returned in the last or only packet of an RDMA
>>>> READ or Atomic response. For RDMA READ requests, the responder
>>>> may increment its MSN after it has completed validating the request and
>>>> before it has begun transmitting any of the requested data, and may
>>>> return
>>>> the incremented MSN in the AETH of the first response packet. The MSN
>>>> shall be incremented only once for any given request message.
>>>>
>>>> "
>>>>
>>>> It seems that the above describe how to handle MSN increment in
>>>> details.
>>> Hi Yanjun,
>>>
>>> Sorry for the late reply.
>>>
>>> Right, 9.7.7.1 GENERATING MSN VALUE section explains Message Sequence

"

...

Since the responder may choose to coalesce acknowledges, a single 
response packet may in fact acknowledge
several request messages. Thus, when it receives a new MSN, the 
requester begins evaluating WQEs on its send queue beginning with the
oldest outstanding WQE and progressing forward.

...

"

In the above, several request messages come. From the SPEC, msn should 
increase based on the number of request messages.

Can your commit handle the above case?


Zhu Yanjun

>> Does your commit take into account of duplicate requests?
> Hi Yanjun,
>
> Responder will check duplicate requests by check_psn() and process them
> by duplicate_request().
> According to the logic of duplicate_request(), responder doesn't
> increase msn for duplicate requests.
>
> Best Regards,
> Xiao Yang
>> Zhu Yanjun
>>
>>> Number(MSN).
>>>
>>> Best Regards,
>>> Xiao Yang
>>>> Zhu Yanjun
>>>>
>>>>> Thxs, Håkon
>>>>>
>>>>>> Thanks a lot.
>>>>>>
>>>>>> Zhu Yanjun
>>>>>>
>>>>>>> Best Regards,
>>>>>>> Xiao Yang