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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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