From patchwork Wed Jan 26 13:01:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Tony Lu X-Patchwork-Id: 12725020 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 7A761C63684 for ; Wed, 26 Jan 2022 13:02:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230400AbiAZNC0 (ORCPT ); Wed, 26 Jan 2022 08:02:26 -0500 Received: from out199-4.us.a.mail.aliyun.com ([47.90.199.4]:59131 "EHLO out199-4.us.a.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229928AbiAZNC0 (ORCPT ); Wed, 26 Jan 2022 08:02:26 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=tonylu@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0V2vapeq_1643202141; Received: from localhost(mailfrom:tonylu@linux.alibaba.com fp:SMTPD_---0V2vapeq_1643202141) by smtp.aliyun-inc.com(127.0.0.1); Wed, 26 Jan 2022 21:02:22 +0800 From: Tony Lu To: kgraul@linux.ibm.com, kuba@kernel.org, davem@davemloft.net Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org Subject: [PATCH net-next 0/2] net/smc: Spread workload over multiple cores Date: Wed, 26 Jan 2022 21:01:39 +0800 Message-Id: <20220126130140.66316-1-tonylu@linux.alibaba.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Currently, SMC creates one CQ per IB device, and shares this cq among all the QPs of links. Meanwhile, this CQ is always binded to the first completion vector, the IRQ affinity of this vector binds to some CPU core. ┌────────┐ ┌──────────────┐ ┌──────────────┐ │ SMC IB │ ├────┐ │ │ │ │ DEVICE │ ┌─▶│ QP │ SMC LINK├──▶│SMC Link Group│ │ ┌────┤ │ ├────┘ │ │ │ │ │ CQ ├─┘ └──────────────┘ └──────────────┘ │ │ ├─┐ ┌──────────────┐ ┌──────────────┐ │ └────┤ │ ├────┐ │ │ │ │ │ └─▶│ QP │ SMC LINK├──▶│SMC Link Group│ │ │ ├────┘ │ │ │ └────────┘ └──────────────┘ └──────────────┘ In this model, when connections execeeds SMC_RMBS_PER_LGR_MAX, it will create multiple link groups and corresponding QPs. All the connections share limited QPs and one CQ (both recv and send sides). Generally, one completion vector binds to a fixed CPU core, it will limit the performance by single core, and large-scale scenes, such as multiple threads and lots of connections. Running nginx and wrk test with 8 threads and 800 connections on 8 cores host, the softirq of CPU 0 is limited the scalability: 04:18:54 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 04:18:55 PM all 5.81 0.00 19.42 0.00 2.94 10.21 0.00 0.00 0.00 61.63 04:18:55 PM 0 0.00 0.00 0.00 0.00 16.80 82.78 0.00 0.00 0.00 0.41 Nowadays, RDMA devices have more than one completion vectors, such as mlx5 has 8, eRDMA has 4 completion vector by default. This unlocks the limitation of single vector and single CPU core. To enhance scalability and take advantage of multi-core resources, we can spread CQs to different CPU cores, and introduce more flexible mapping. Here comes up a new model, the main different is that creating multiple CQs per IB device, which the max number of CQs is limited by ibdev's ability (num_comp_vectors). In the scene of multiple linkgroups, the link group's QP can bind to the least used CQ, and CQs are binded to different completion vector and CPU cores. So that we can spread the softirq (tasklet of wr tx/rx) handler to different cores. ┌──────────────┐ ┌──────────────┐ ┌────────┐ ┌───────┐ ├────┐ │ │ │ │ ├─▶│ CQ 0 ├──▶│ QP │ SMC LINK├──▶│SMC Link Group│ │ │ └───────┘ ├────┘ │ │ │ │ SMC IB │ ┌───────┐ └──────────────┘ └──────────────┘ │ DEVICE ├─▶│ CQ 1 │─┐ │ │ └───────┘ │ ┌──────────────┐ ┌──────────────┐ │ │ ┌───────┐ │ ├────┐ │ │ │ │ ├─▶│ CQ n │ └▶│ QP │ SMC LINK├──▶│SMC Link Group│ └────────┘ └───────┘ ├────┘ │ │ │ └──────────────┘ └──────────────┘ After sperad one CQ (4 linkgroups) to four CPU cores, the softirq load spreads to different cores: 04:26:25 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 04:26:26 PM all 10.70 0.00 35.80 0.00 7.64 26.62 0.00 0.00 0.00 19.24 04:26:26 PM 0 0.00 0.00 0.00 0.00 16.33 50.00 0.00 0.00 0.00 33.67 04:26:26 PM 1 0.00 0.00 0.00 0.00 15.46 69.07 0.00 0.00 0.00 15.46 04:26:26 PM 2 0.00 0.00 0.00 0.00 13.13 39.39 0.00 0.00 0.00 47.47 04:26:26 PM 3 0.00 0.00 0.00 0.00 13.27 55.10 0.00 0.00 0.00 31.63 Here is the benchmark with this patch set: Test environment: - CPU Intel Xeon Platinum 8 core, mem 32 GiB, nic Mellanox CX4. - nginx + wrk HTTP benchmark. - nginx: disable access_log, increase keepalive_timeout and keepalive_requests, long-live connection, return 200 directly. - wrk: 8 threads and 100, 200, 400 connections. Benchmark result: Conns/QPS 100 200 400 w/o patch 338502.49 359216.66 398167.16 w/ patch 677247.40 694193.70 812502.69 Ratio +100.07% +93.25% +104.06% This patch set shows nearly 1x increasement of QPS. The benchmarks of 100, 200, 400 connections use 1, 1, 2 link groups. When link group is one, it spreads send/recv to two cores. Once more than one link groups, it would spread to more cores. RFC Link: https://lore.kernel.org/netdev/YeRaSdg8TcNJsGBB@TonyMac-Alibaba/T/ These two patches split from previous RFC, and move netlink related patch to the next patch set. Tony Lu (2): net/smc: Introduce smc_ib_cq to bind link and cq net/smc: Multiple CQs per IB devices net/smc/smc_core.h | 2 + net/smc/smc_ib.c | 132 ++++++++++++++++++++++++++++++++++++--------- net/smc/smc_ib.h | 15 ++++-- net/smc/smc_wr.c | 44 +++++++++------ 4 files changed, 148 insertions(+), 45 deletions(-)