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Message-ID: <308362d1-0dd2-2253-ced2-6defe1a7857e@linux.alibaba.com> Date: Wed, 13 Dec 2023 17:41:19 +0800 From: Wen Gu <guwen@...ux.alibaba.com> To: shaozhengchao <shaozhengchao@...wei.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 2023/12/13 17:00, shaozhengchao wrote: > > > On 2023/12/5 14:45, shaozhengchao wrote: >> >> >> On 2023/12/4 12:06, shaozhengchao wrote: >>> >>> >>> 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 >>> >> Hi Wen Gu: >> I've tested all the performance test items in the patchset. The >> performance improvement is to be expected, except for nignx. >> My VM is configured with 48 cores and 32 GB memory. Therefore, run >> the following command: >> <smc_run> nignx >> <smc_run>./wrk -t 96 -c 1000 -d 30 http://127.0.0.1:80 >> >> The test results are as follows: >> TCP SMC_lo >> Requests/s 309425.42 135547.25(-56.19%) >> The performance decreases by 56.19%. >> >> I capture packets and find that wrk can perform HTTP GET after each >> connect when smc_loopback is disabled. >> However, when smc_loopback is enabled, there is no HTTP GET behavior. >> I wonder if there is some compatibility problem with the SMC protocol when encapsulate packet? Could you give me some >> advice? >> In the attachment, I captured some of the packets. >> nosmc_nginx.pcap is for SMC disabled and smc_nginx.pcap is for SMC >> enabled. >> Thank you very much. >> >> Zhengchao Shao >> >> >> > Hi Wen Gu: > When the VM is configured with 8 cores and 16 GB memory, run > the following command: > <smc_run> nignx > <smc_run>./wrk -t 8 -c 1000 -d 30 http://127.0.0.1:80 > the test data is as follows: > TCP SMC_lo > Requests/s 66056.66 94526.66(43.10%) > > But When the VM is configured with 48 cores and 32 GB memory, run > the following command: > <smc_run> nignx > <smc_run>./wrk -t 96 -c 1000 -d 30 http://127.0.0.1:80 > the test data is as follows: > TCP SMC_lo > Requests/s 309425.42 135547.25(-56.19%) > > It seems that in the scenario with a large number of CPU cores, > performance is not optimized, but performance deteriorates. What I > missed? > Thank you. > > Zhengchao Shao Hi Zhengchao Shao, Somehow I missed your email on 12/05. I will try to reproduce this issue in my test environment and let you know if I find anything. Best Regards, Wen Gu
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