From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64C3AC433FE for ; Wed, 9 Nov 2022 09:11:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230173AbiKIJLS (ORCPT ); Wed, 9 Nov 2022 04:11:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229545AbiKIJKf (ORCPT ); Wed, 9 Nov 2022 04:10:35 -0500 Received: from out30-42.freemail.mail.aliyun.com (out30-42.freemail.mail.aliyun.com [115.124.30.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2534E22B1F; Wed, 9 Nov 2022 01:10:14 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R201e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046060;MF=alibuda@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0VUNUlIt_1667985011; Received: from 30.221.149.123(mailfrom:alibuda@linux.alibaba.com fp:SMTPD_---0VUNUlIt_1667985011) by smtp.aliyun-inc.com; Wed, 09 Nov 2022 17:10:12 +0800 Message-ID: <901fbb4e-9dd0-adb8-a854-44930a601a9d@linux.alibaba.com> Date: Wed, 9 Nov 2022 17:10:10 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.13.1 Subject: Re: [PATCH net-next v4 00/10] optimize the parallelism of SMC-R connections Content-Language: en-US From: "D. Wythe" To: Wenjia Zhang , Jan Karcher , kgraul@linux.ibm.com Cc: kuba@kernel.org, davem@davemloft.net, netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org References: <1666529042-40828-1-git-send-email-alibuda@linux.alibaba.com> <95feb2a1-d17a-6233-d3d0-eaebf26d2284@linux.ibm.com> <1615836b-3087-2467-262e-f402ec521716@linux.alibaba.com> <3526d73b-a0cf-e9eb-383b-2ad917f3bcc2@linux.ibm.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org Hi Wenjia and Jan, I'm not sure whether my guess is right, I need some help from you. I guess the smcd_ops register_dmb() is not thread-safe, after I remove the lock, different connections might get the same sba_idx, which will cause the connection to be lost in the map(smcd->conn). If so, the CDC message carrying close/abort information cannot be distributed to the correct connection, then the connection remains in link group abnormally. /* Set a connection using this DMBE. */ void smc_ism_set_conn(struct smc_connection *conn) { unsigned long flags; spin_lock_irqsave(&conn->lgr->smcd->lock, flags); conn->lgr->smcd->conn[conn->rmb_desc->sba_idx] = conn; spin_unlock_irqrestore(&conn->lgr->smcd->lock, flags); } struct smcd_ops { int (*register_dmb)(struct smcd_dev *dev, struct smcd_dmb *dmb); } On 11/7/22 7:05 PM, D. Wythe wrote: > > Hi Wenjia, > > Thanks a lot for your information, before that we thought you did PATCH test one by one, > now I think I have found the root cause, and I will release a new version to fix this > soon as possible. > > Best Wishes. > D. Wythe > > On 11/2/22 9:55 PM, Wenjia Zhang wrote: >> >> >> On 01.11.22 08:22, D. Wythe wrote: >>> >>> Hi Jan, >>> >>> Our team conducted some code reviews over this, but unfortunately no obvious problems were found. Hence >>> we are waiting for Tony Lu's virtual SMC-D device to test, which is expected to come in this week.  Before that, >>> I wonder if your tests are running separately on separate PATCH? If so, I would like to please you to test >>> the first PATCH and the second PATCH together. I doubt that the problem repaired by the second PATCH >>> is the cause of this issues. >>> >>> Best Wishes. >>> D. Wythe >>> >> >> Hi D. Wythe, >> >> We did test the series of the patches as a whole. That would be great if you could use Tony's virtual device to test SMC-D. By the way, I'll put your patches in our CI, let's see if it can find something. >> >> Best, >> Wenjia >>> >>> On 10/24/22 9:11 PM, Jan Karcher wrote: >>>> Hi D. Wythe, >>>> >>>> I re-run the tests with your fix. >>>> SMC-R works fine now. For SMC-D we still have the following problem. It is kind of the same as i reported in v2 but even weirder: >>>> >>>> smc stats: >>>> >>>> t8345011 >>>> SMC-D Connections Summary >>>>    Total connections handled          2465 >>>> SMC-R Connections Summary >>>>    Total connections handled           232 >>>> >>>> t8345010 >>>> SMC-D Connections Summary >>>>    Total connections handled          2290 >>>> SMC-R Connections Summary >>>>    Total connections handled           231 >>>> >>>> >>>> smc linkgroups: >>>> >>>> t8345011 >>>> [root@t8345011 ~]# smcr linkgroup >>>> LG-ID    LG-Role  LG-Type  VLAN  #Conns  PNET-ID >>>> 00000400 SERV     SYM         0       0  NET25 >>>> [root@t8345011 ~]# smcd linkgroup >>>> LG-ID    VLAN  #Conns  PNET-ID >>>> 00000300    0      16  NET25 >>>> >>>> t8345010 >>>> [root@t8345010 tela-kernel]# smcr linkgroup >>>> LG-ID    LG-Role  LG-Type  VLAN  #Conns  PNET-ID >>>> 00000400 CLNT     SYM         0       0  NET25 >>>> [root@t8345010 tela-kernel]# smcd linkgroup >>>> LG-ID    VLAN  #Conns  PNET-ID >>>> 00000300    0       1  NET25 >>>> >>>> >>>> smcss: >>>> >>>> t8345011 >>>> [root@t8345011 ~]# smcss >>>> State          UID   Inode   Local Address           Peer Address Intf Mode >>>> >>>> t8345010 >>>> [root@t8345010 tela-kernel]# smcss >>>> State          UID   Inode   Local Address           Peer Address Intf Mode >>>> >>>> >>>> lsmod: >>>> >>>> t8345011 >>>> [root@t8345011 ~]# lsmod | grep smc >>>> smc                   225280  18 ism,smc_diag >>>> t8345010 >>>> [root@t8345010 tela-kernel]# lsmod | grep smc >>>> smc                   225280  3 ism,smc_diag >>>> >>>> Also smc_dbg and netstat do not show any more information on this problem. We only see in the dmesg that the code seems to build up SMC-R linkgroups even tho we are running the SMC-D tests. >>>> NOTE: we disabled the syncookies for the tests. >>>> >>>> dmesg: >>>> >>>> t8345011 >>>> smc-tests: test_smcapp_torture_test started >>>> kernel: TCP: request_sock_TCP: Possible SYN flooding on port 22465. Dropping request.  Check SNMP counters. >>>> kernel: smc: SMC-R lg 00000400 net 1 link added: id 00000401, peerid 00000401, ibdev mlx5_0, ibport 1 >>>> kernel: smc: SMC-R lg 00000400 net 1 state changed: SINGLE, pnetid NET25 >>>> kernel: smc: SMC-R lg 00000400 net 1 link added: id 00000402, peerid 00000402, ibdev mlx5_1, ibport 1 >>>> kernel: smc: SMC-R lg 00000400 net 1 state changed: SYMMETRIC, pnetid NET25 >>>> >>>> t8345010 >>>> smc-tests: test_smcapp_torture_test started >>>> kernel: smc: SMC-R lg 00000400 net 1 link added: id 00000401, peerid 00000401, ibdev mlx5_0, ibport 1 >>>> kernel: smc: SMC-R lg 00000400 net 1 state changed: SINGLE, pnetid NET25 >>>> kernel: smc: SMC-R lg 00000400 net 1 link added: id 00000402, peerid 00000402, ibdev mlx5_1, ibport 1 >>>> kernel: smc: SMC-R lg 00000400 net 1 state changed: SYMMETRIC, pnetid NET25 >>>> >>>> If this output does not help and if you want us to look deeper into it feel free to let us know and we can debug further. >>>> >>>> On 23/10/2022 14:43, D.Wythe wrote: >>>>> From: "D.Wythe" >>>>> >>>>> This patch set attempts to optimize the parallelism of SMC-R connections, >>>>> mainly to reduce unnecessary blocking on locks, and to fix exceptions that >>>>> occur after thoses optimization. >>>>> >>>>> According to Off-CPU graph, SMC worker's off-CPU as that: >>>>> >>>>> smc_close_passive_work                  (1.09%) >>>>>          smcr_buf_unuse                  (1.08%) >>>>>                  smc_llc_flow_initiate   (1.02%) >>>>> >>>>> smc_listen_work                         (48.17%) >>>>>          __mutex_lock.isra.11            (47.96%) >>>>> >>>>> >>>>> An ideal SMC-R connection process should only block on the IO events >>>>> of the network, but it's quite clear that the SMC-R connection now is >>>>> queued on the lock most of the time. >>>>> >>>>> The goal of this patchset is to achieve our ideal situation where >>>>> network IO events are blocked for the majority of the connection lifetime. >>>>> >>>>> There are three big locks here: >>>>> >>>>> 1. smc_client_lgr_pending & smc_server_lgr_pending >>>>> >>>>> 2. llc_conf_mutex >>>>> >>>>> 3. rmbs_lock & sndbufs_lock >>>>> >>>>> And an implementation issue: >>>>> >>>>> 1. confirm/delete rkey msg can't be sent concurrently while >>>>> protocol allows indeed. >>>>> >>>>> Unfortunately,The above problems together affect the parallelism of >>>>> SMC-R connection. If any of them are not solved. our goal cannot >>>>> be achieved. >>>>> >>>>> After this patch set, we can get a quite ideal off-CPU graph as >>>>> following: >>>>> >>>>> smc_close_passive_work                                  (41.58%) >>>>>          smcr_buf_unuse                                  (41.57%) >>>>>                  smc_llc_do_delete_rkey                  (41.57%) >>>>> >>>>> smc_listen_work                                         (39.10%) >>>>>          smc_clc_wait_msg                                (13.18%) >>>>>                  tcp_recvmsg_locked                      (13.18) >>>>>          smc_listen_find_device                          (25.87%) >>>>>                  smcr_lgr_reg_rmbs                       (25.87%) >>>>>                          smc_llc_do_confirm_rkey         (25.87%) >>>>> >>>>> We can see that most of the waiting times are waiting for network IO >>>>> events. This also has a certain performance improvement on our >>>>> short-lived conenction wrk/nginx benchmark test: >>>>> >>>>> +--------------+------+------+-------+--------+------+--------+ >>>>> |conns/qps     |c4    | c8   |  c16  |  c32   | c64  |  c200  | >>>>> +--------------+------+------+-------+--------+------+--------+ >>>>> |SMC-R before  |9.7k  | 10k  |  10k  |  9.9k  | 9.1k |  8.9k  | >>>>> +--------------+------+------+-------+--------+------+--------+ >>>>> |SMC-R now     |13k   | 19k  |  18k  |  16k   | 15k  |  12k   | >>>>> +--------------+------+------+-------+--------+------+--------+ >>>>> |TCP           |15k   | 35k  |  51k  |  80k   | 100k |  162k  | >>>>> +--------------+------+------+-------+--------+------+--------+ >>>>> >>>>> The reason why the benefit is not obvious after the number of connections >>>>> has increased dues to workqueue. If we try to change workqueue to UNBOUND, >>>>> we can obtain at least 4-5 times performance improvement, reach up to half >>>>> of TCP. However, this is not an elegant solution, the optimization of it >>>>> will be much more complicated. But in any case, we will submit relevant >>>>> optimization patches as soon as possible. >>>>> >>>>> Please note that the premise here is that the lock related problem >>>>> must be solved first, otherwise, no matter how we optimize the workqueue, >>>>> there won't be much improvement. >>>>> >>>>> Because there are a lot of related changes to the code, if you have >>>>> any questions or suggestions, please let me know. >>>>> >>>>> Thanks >>>>> D. Wythe >>>>> >>>>> v1 -> v2: >>>>> >>>>> 1. Fix panic in SMC-D scenario >>>>> 2. Fix lnkc related hashfn calculation exception, caused by operator >>>>> priority >>>>> 3. Only wake up one connection if the lnk is not active >>>>> 4. Delete obsolete unlock logic in smc_listen_work() >>>>> 5. PATCH format, do Reverse Christmas tree >>>>> 6. PATCH format, change all xxx_lnk_xxx function to xxx_link_xxx >>>>> 7. PATCH format, add correct fix tag for the patches for fixes. >>>>> 8. PATCH format, fix some spelling error >>>>> 9. PATCH format, rename slow to do_slow >>>>> >>>>> v2 -> v3: >>>>> >>>>> 1. add SMC-D support, remove the concept of link cluster since SMC-D has >>>>> no link at all. Replace it by lgr decision maker, who provides suggestions >>>>> to SMC-D and SMC-R on whether to create new link group. >>>>> >>>>> 2. Fix the corruption problem described by PATCH 'fix application >>>>> data exception' on SMC-D. >>>>> >>>>> v3 -> v4: >>>>> >>>>> 1. Fix panic caused by uninitialization map. >>>>> >>>>> D. Wythe (10): >>>>>    net/smc: remove locks smc_client_lgr_pending and >>>>>      smc_server_lgr_pending >>>>>    net/smc: fix SMC_CLC_DECL_ERR_REGRMB without smc_server_lgr_pending >>>>>    net/smc: allow confirm/delete rkey response deliver multiplex >>>>>    net/smc: make SMC_LLC_FLOW_RKEY run concurrently >>>>>    net/smc: llc_conf_mutex refactor, replace it with rw_semaphore >>>>>    net/smc: use read semaphores to reduce unnecessary blocking in >>>>>      smc_buf_create() & smcr_buf_unuse() >>>>>    net/smc: reduce unnecessary blocking in smcr_lgr_reg_rmbs() >>>>>    net/smc: replace mutex rmbs_lock and sndbufs_lock with rw_semaphore >>>>>    net/smc: Fix potential panic dues to unprotected >>>>>      smc_llc_srv_add_link() >>>>>    net/smc: fix application data exception >>>>> >>>>>   net/smc/af_smc.c   |  70 ++++---- >>>>>   net/smc/smc_core.c | 478 +++++++++++++++++++++++++++++++++++++++++++++++------ >>>>>   net/smc/smc_core.h |  36 +++- >>>>>   net/smc/smc_llc.c  | 277 ++++++++++++++++++++++--------- >>>>>   net/smc/smc_llc.h  |   6 + >>>>>   net/smc/smc_wr.c   |  10 -- >>>>>   net/smc/smc_wr.h   |  10 ++ >>>>>   7 files changed, 712 insertions(+), 175 deletions(-) >>>>>