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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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