netdev - Re: [PATCH net-next 0/4] Make SMC-R can work with rxe devices

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Message-ID: <ab89629e-75ec-4750-a4e1-58ad287ce1bd@huawei.com>
Date: Sat, 24 Aug 2024 18:04:09 +0800
From: "liujian (CE)" <liujian56@...wei.com>
To: <dust.li@...ux.alibaba.com>, Jan Karcher <jaka@...ux.ibm.com>,
	<linux-rdma@...r.kernel.org>, <linux-s390@...r.kernel.org>,
	<netdev@...r.kernel.org>
CC: <jgg@...pe.ca>, <leon@...nel.org>, <zyjzyj2000@...il.com>,
	<wenjia@...ux.ibm.com>, <alibuda@...ux.alibaba.com>,
	<tonylu@...ux.alibaba.com>, <guwen@...ux.alibaba.com>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>
Subject: Re: [PATCH net-next 0/4] Make SMC-R can work with rxe devices



在 2024/8/21 9:03, Dust Li 写道:
> On 2024-08-20 15:16:57, Jan Karcher wrote:
>>
>>
>> On 09/08/2024 10:31, Liu Jian wrote:
>>> Make SMC-R can work with rxe devices. This allows us to easily test and
>>> learn the SMC-R protocol without relying on a physical RoCE NIC.
>>
>> Hi Liu,
>>
>> sorry for taking quite some time to answer.
>>
>> Looking into this i cannot accept this series at the given point of time.
>>
>> FWIU, RXE is mainly for testing and development and i agree that it would be
>> a nice thing to have for SMC-R.
>> The problem is that there is no clean layer for different RoCE devices
>> currently. Adding RXE to it works but isn't clean.
> 
> Hi jan,
> 
>> Also we have no way to do a "test" build which would have such a device
>> supported and a "prod" build which would not support it.
>  > I don't quite understand what you mean here, Maybe I missed something ?
> IIUC, we can control whether to use RXE by simpling insmod or rmmod rdma_rxe.ko
> 
Yes, in the "prod" environment, we can completely turn off CONFIG_RDMA_RXE.

> I believe having RXE support is beneficial for testing, especially in
> simple physical networking setups where many corner cases are unlikely
> to occur. By using RXE, we can easily configure unusual scenarios with
> the existing iptables/netfilter infrastructure to simulate real-world
> situations, such as packet dropping or network retransmission. This
> approach can be advantageous for finding hidden bugs.
> 
Yes, one of my main original intentions was to make testing smc-r 
easier. This change is relatively simple, mainly patch2 and patch4, and 
there are no logical changes.
> Best regards,
> Dust
> 
> 
>>
>> Please give us time to investigate how to solve this in a neat way without
>> building up to much technical debt.
>>
>> Thanks for your contribution and making us aware of this area of improvment.
>> - Jan
>>
>>>
>>> Liu Jian (4):
>>>     rdma/device: export ib_device_get_netdev()
>>>     net/smc: use ib_device_get_netdev() helper to get netdev info
>>>     net/smc: fix one NULL pointer dereference in smc_ib_is_sg_need_sync()
>>>     RDMA/rxe: Set queue pair cur_qp_state when being queried
>>>
>>>    drivers/infiniband/core/core_priv.h   |  3 ---
>>>    drivers/infiniband/core/device.c      |  1 +
>>>    drivers/infiniband/sw/rxe/rxe_verbs.c |  2 ++
>>>    include/rdma/ib_verbs.h               |  2 ++
>>>    net/smc/smc_ib.c                      | 10 +++++-----
>>>    net/smc/smc_pnet.c                    |  6 +-----
>>>    6 files changed, 11 insertions(+), 13 deletions(-)
>>>