netdev - Re: [net-next 0/2] Deliver confirm/delete rkey message in parallel

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Date:   Wed, 8 Feb 2023 11:09:48 +0800
From:   "D. Wythe" <alibuda@...ux.alibaba.com>
To:     Wenjia Zhang <wenjia@...ux.ibm.com>, kgraul@...ux.ibm.com,
        jaka@...ux.ibm.com
Cc:     kuba@...nel.org, davem@...emloft.net, netdev@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org
Subject: Re: [net-next 0/2] Deliver confirm/delete rkey message in parallel



On 2/8/23 11:04 AM, D. Wythe wrote:
> 
> 
> On 2/8/23 7:29 AM, Wenjia Zhang wrote:
>>
>>
>> On 07.02.23 08:36, D. Wythe wrote:
>>> From: "D. Wythe" <alibuda@...ux.alibaba.com>
>>>
>>> According to the SMC protocol specification, we know that all flows except
>>> confirm_rkey adn delete_rkey are exclusive, confirm/delete rkey flows
>>> can run concurrently (local and remote).
>>>
>>> However, although the protocol allows, all flows are actually mutually
>>> exclusive in implementation, deus to we are waiting for LLC message
>>> in serial.
>>>
>>> On the one hand, this implementation does not conform to the protocol
>>> specification, on the other hand, this implementation aggravates the
>>> time for establishing or destroying a SMC-R connection, connection
>>> have to be queued in smc_llc_wait.
>>>
>>> This patch will improve the performance of the short link scenario
>>> by about 5%. In fact, we all know that the performance bottleneck
>>> of the short link scenario is not here.
>>>
>>> This patch try use rtokens or rkey to correlate a confirm/delete
>>> rkey message with its response.
>>>
>>> This patch contains two parts.
>>>
>>> At first, we have added the process
>>> of asynchronously waiting for the response of confirm/delete rkey
>>> messages, using rtokens or rkey to be correlate with.
>>>
>>> And then, we try to send confirm/delete rkey message in parallel,
>>> allowing parallel execution of start (remote) or initialization (local)
>>> SMC_LLC_FLOW_RKEY flows.
>>>
>>> D. Wythe (2):
>>>    net/smc: allow confirm/delete rkey response deliver multiplex
>>>    net/smc: make SMC_LLC_FLOW_RKEY run concurrently
>>>
>>>   net/smc/smc_core.h |   1 +
>>>   net/smc/smc_llc.c  | 263 +++++++++++++++++++++++++++++++++++++++++------------
>>>   net/smc/smc_llc.h  |   6 ++
>>>   net/smc/smc_wr.c   |  10 --
>>>   net/smc/smc_wr.h   |  10 ++
>>>   5 files changed, 220 insertions(+), 70 deletions(-)
>>>
>>
>> As we already discussed, on this changes we need to test them carefully so that we have to be sure that the communicating with z/OS should not be broken. We'll let you know as soon as the testing is finished.
> 
> 
> Hi, Wenjia
> 
> Thanks again for your test.
> 
> Considering that we have reached an agreement on protocol extension,
> we can temporarily postpone this modification until we introduce the protocol extension
> into the Linux community version. Then we can avoid the compatibility with z/OS.
> 
> 
> Best wishes.
> D. Wythe
> 

We can temporarily postpone this modification until we introduce the protocol extension
into the Linux community version IF we can't pass the z/OS compatible test. :-)

Sorry for the problem in my description.

Thanks.
D. Wythe