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Message-ID: <488311be-5673-552c-d932-26f87e863777@huawei.com>
Date: Mon, 4 Dec 2023 12:06:59 +0800
From: shaozhengchao <shaozhengchao@...wei.com>
To: Wen Gu <guwen@...ux.alibaba.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, yuehaibing
	<yuehaibing@...wei.com>, "Libin (Huawei)" <huawei.libin@...wei.com>, Dust Li
	<dust.li@...ux.alibaba.com>, tonylu_linux <tonylu@...ux.alibaba.com>, "D.
 Wythe" <alibuda@...ux.alibaba.com>
Subject: Re: [question] smc: how to enable SMC_LO feature



On 2023/12/4 11:52, Wen Gu wrote:
> 
> On 2023/12/4 11:22, shaozhengchao wrote:
>>
>>
>> On 2023/11/23 14:15, shaozhengchao wrote:
>>>
>>>
>>> On 2023/11/23 10:21, Wen Gu wrote:
>>>>
>>>>
>>>> On 2023/11/21 20:14, shaozhengchao wrote:
>>>>> Hi Wen Gu:
>>>>> Currently, I am interested in the SMC_LOOPBACK feature proposed
>>>>> by you. Therefore, I use your patchset[1] to test the SMC_LO 
>>>>> feature on
>>>>> my x86_64 environment and kernel is based on linux-next, commit: 
>>>>> 5ba73bec5e7b.
>>>>> The test result shows that the smc_lo feature cannot be enabled. 
>>>>> Here's
>>>>> my analysis:
>>>>>
>>>>> 1. Run the following command to perform the test, and then capture
>>>>> packets on the lo device.
>>>>> - serv:  smc_run taskset -c <cpu> sockperf sr --tcp
>>>>> - clnt:  smc_run taskset -c <cpu> sockperf  tp --tcp 
>>>>> --msg-size=64000 -i 127.0.0.1 -t 30
>>>>>
>>>>> 2. Use Wireshark to open packets. It is found that the VCE port 
>>>>> replies with
>>>>> SMC-R-Deline packets.
>>>>> [cid:image001.png@...A1CB4.F1052C30]
>>>>>
>>>>> 3. Rx
>>>>> When smc_listen_work invokes smc_listen_v2_check, the VCE port returns
>>>>> a Decline packet because eid_cnt and flag.seid in the received 
>>>>> packet are both 0.
>>>>>
>>>>> 4. Tx
>>>>> In smc_clc_send_proposal,
>>>>> v2_ext->hdr.eid_cnt = smc_clc_eid_table.ueid_cnt;
>>>>> v2_ext->hdr.flag.seid = smc_clc_eid_table.seid_enabled;
>>>>>
>>>>> When smc_clc_init, ueid_cnt=0, and in the x86_64 environment, 
>>>>> seid_enabled is
>>>>> always equal to 0.
>>>>>
>>>>> So, I must call smc_clc_ueid_add function to increase ueid count?
>>>>> But I don't see where operations can be added, may I missed something?
>>>>>
>>>>
>>>> Hi Zhengchao Shao,
>>>>
>>>> Yes. When using SMC-D in non-s390 architecture (like x86 here), A 
>>>> common
>>>> UEID should be set. It can be set by following steps:
>>>>
>>>> - Install smc-tools[1].
>>>>
>>>> - Run # smcd ueid add <ueid> in loopback test environment.
>>>>
>>>>    EID works as an ID to indicate the max communication space of 
>>>> SMC. When SEID is
>>>>    unavailable, an UEID is required.
>>>>
>>> Hi Wen Gu:
>>>      Thank you for your reply. This is very useful for me. And I will
>>> be happy to learn from it.
>>>
>>> Thanks
>>>
>>> Zhengchao Shao
>>>> - Then run the test.
>>>>
>>>> Hope this works for you :)
>>>>
>>>> [1] https://github.com/ibm-s390-linux/smc-tools
>>>>
>>>> Regards,
>>>> Wen Gu
>>>>
>>>>> Could you give me some advice? Thanks very much.
>>>>>
>>>>> Zhengchao Shao
>>>>>
>>>>>
>>>>> [1]link: 
>>>>> https://patchwork.kernel.org/project/netdevbpf/cover/1695568613-125057-1-git-send-email-guwen@linux.alibaba.com/
>>>>>
>>>>
>>>
>>>
>> Hi Wen Gu:
>>      I have test as following, but the performance is really
>> degraded. Now I have no idea.
>> 1. add ueid
>> run: smcd ueid add 16
>> kernel message:
>> [ 5252.009133] NET: Registered PF_SMC protocol family
>> [ 5252.009233] smc: adding smcd device smc_lo with pnetid
>> 2. start server
>> smc_run taskset -c 1 sockperf sr --tcp
>> 3. start client
>> smc_run taskset -c 3 sockperf tp  --tcp --msg-size=64000 -i 127.0.0.1 
>> -t 30
>>
>> The test results are as follows:
>>                TCP                  SMC-lo
>> Bandwidth(MBps)         1890.56               1300.41(-31.22%)
>>
>> I didn't find a better direction when I initially positioned it. No
>> error is recorded in the kernel log, and the smcd statistics are normal.
>> [root@...alhost smc-tools]# smcd stats
>> SMC-D Connections Summary
>>    Total connections handled             2
>>    SMC connections                       2
>>    Handshake errors                      0
>>    Avg requests per SMC conn       1277462.0
>>    TCP fallback                          0
>>
>> RX Stats
>>    Data transmitted (Bytes)    40907328000 (40.91G)
>>    Total requests                  1277190
>>    Buffer full                          45 (0.00%)
>>              8KB    16KB    32KB    64KB   128KB   256KB   512KB  >512KB
>>    Bufs        0       0       0       2       0       0       0       0
>>    Reqs   638.0K       0       0  639.2K       0       0       0       0
>>
>> TX Stats
>>    Data transmitted (Bytes)    40907328000 (40.91G)
>>    Total requests                  1277734
>>    Buffer full                      638239 (49.95%)
>>    Buffer full (remote)                  0 (0.00%)
>>    Buffer too small                      0 (0.00%)
>>    Buffer too small (remote)             0 (0.00%)
>>              8KB    16KB    32KB    64KB   128KB   256KB   512KB  >512KB
>>    Bufs        0       0       0       0       0       0       0       0
>>    Reqs        0       0       0  1.278M       0       0       0       0
>>
>> Extras
>>    Special socket calls                  1
>>
>> I captured the perf information and found that the percentage of
>> rep_movs_alternative and _raw_spin_unlock_irqrestore functions was high
>> during tx and rx.
>> 36.12%  [kernel]         [k]rep_movs_alternative
>> 14.23%  [kernel]         [k]_raw_spin_unlock_irqrestore
>>
>> I've attached the flame map. Could you help analyze it? What I missed?
>> Thanks.
> 
> Hi Zhengchao Shao,
> 
> Since sndbuf and RMB in SMC are pre-alloced ringbuf and won't grow 
> dynamically
> like TCP, it is necessary to appropriately increase the default value of 
> smc
> sk_sndbuf and sk_rcvbuf before testing throughput.
> 
> Set this and try again:
> 
> # sysctl -w net.smc.wmem=1048576
> # sysctl -w net.smc.rmem=1048576
> 
> (The initial value of wmem and rmem are 64K)
> 
> Regards,
> Wen Gu
> 
>>
>> Zhengchao Shao
Hi Wen Gu:
	It solves the issue. Thank you very much.

Zhengchao Shao

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