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 7C311C4332F for ; Mon, 7 Nov 2022 11:06:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231145AbiKGLF6 (ORCPT ); Mon, 7 Nov 2022 06:05:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59056 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229929AbiKGLF6 (ORCPT ); Mon, 7 Nov 2022 06:05:58 -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 9217C14D36; Mon, 7 Nov 2022 03:05:55 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046049;MF=alibuda@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0VUC7jcl_1667819138; Received: from 30.221.146.249(mailfrom:alibuda@linux.alibaba.com fp:SMTPD_---0VUC7jcl_1667819138) by smtp.aliyun-inc.com; Mon, 07 Nov 2022 19:05:52 +0800 Message-ID: Date: Mon, 7 Nov 2022 19:05:37 +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 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> From: "D. Wythe" In-Reply-To: <3526d73b-a0cf-e9eb-383b-2ad917f3bcc2@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org 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(-) >>>>