Received: by 2002:a05:6a10:af89:0:0:0:0 with SMTP id iu9csp759076pxb; Fri, 28 Jan 2022 09:20:31 -0800 (PST) X-Google-Smtp-Source: ABdhPJxpS1mM2JLbXTqd/MtQqrdZv9G5Yp9LJ0A24Fkm/OsXwxP3HaFjkoUGMVpeQmP9/2ZHte2w X-Received: by 2002:a17:90b:4f83:: with SMTP id qe3mr20755416pjb.120.1643390431035; Fri, 28 Jan 2022 09:20:31 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1643390431; cv=none; d=google.com; s=arc-20160816; b=m0WRyZxz4g//tC+mJozOPxzIvpS0MY1ajzPRiEUaVppoGR8bRzFoakQDWACK2ntoj4 WFHlVIQSP9pL5NWXE0Rq+t2DdsK2M0PaNHQwGPfbdqOQ3hljC8mq8aZkhxFfljnuIyUk oes8GCV3JoE8gKMO55feYnsGVOgdTTyIUOko2Xp7pE96HbL/I2QqzO+/ouJNlckRzJnf 7lFIQpulR0pcR9iLBgZSVNVJpH6GsxCKQcHhX81sqfmDS0huEz2BN0+fChwGR1/j5jBn lp6qGdJNkGWidItDDavf0vZMdCFi2WgJofaWXuQpGCoPlxd+ugMfAOqCtNLyIXP+IOGv jM+A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:subject:message-id:date:from:in-reply-to :references:mime-version:dkim-signature; bh=zteXgpZ/JH4IqimdwPBayrW7aIOlMpDuJVk4lYJ5/YU=; b=a5FG+tZDD1ufQIz9fICIWrluTx1eMzub1drRXDh8Ymf4SacbmLbnbRL1bU1MfAoCu1 M0eP7H438Rn27Gfil/ekteod2QybOEkrmhXpS9xgkdjw1b+Q8FWw1OJ2eNzMDvA2JVvc v7Y2VvPki6fBdGcWxYy5NISGCaxpoJydIq06jqVuPt7qSM3/vAMhPcffxwlhCVSLAoSy ENV+Cbve4eKHyhr4wYV3C87Cf5uBOVQ9TNcjJ1QNs8BMsQ6K06v01aeMiEgpJXlP6J6Y 9eGfMUFAsEEqEF/e0bdiHlkAoKaVoJwLJRtnu9V4k9JlxjWq48py2qcRtUaBI7m8t8wm Pkzw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=WaiASpp0; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id v9si6263622plg.338.2022.01.28.09.20.18; Fri, 28 Jan 2022 09:20:31 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=WaiASpp0; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343991AbiA0UVX (ORCPT + 99 others); Thu, 27 Jan 2022 15:21:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48016 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343981AbiA0UVW (ORCPT ); Thu, 27 Jan 2022 15:21:22 -0500 Received: from mail-ej1-x634.google.com (mail-ej1-x634.google.com [IPv6:2a00:1450:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74338C061714 for ; Thu, 27 Jan 2022 12:21:21 -0800 (PST) Received: by mail-ej1-x634.google.com with SMTP id m4so8417208ejb.9 for ; Thu, 27 Jan 2022 12:21:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=zteXgpZ/JH4IqimdwPBayrW7aIOlMpDuJVk4lYJ5/YU=; b=WaiASpp09I4cE41LfRl1IYElP2t6jW/Urgc9CLi/V/9T1HmCIjuqjmzUjKMrfq1BWv 9VlKEWW9pcyZcKsHjqC10GF4CyH+P4+r4341qe4OSmg0M5Fy7dZrAHtngVabykR9Uvft 6RpAKb2PPUpdmvw/wtlEc+6ZP1F/xVcPSlirRFFwpKBqjncJ+UxNzk4/XCA+XxRAJWNf GZx2w8q4jrJnWLdPkMvpEvWQDV7Gz507O8K1KykA95mcAy38Hf6vCdaSNBe/UVu1eB56 n8Ne6oPzgkvz8nrMoX5aCgcSH+g0pEy1kPvtG8lvm7ST/AdHV+nkLbO9wBmyMqv6B+2q qOnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=zteXgpZ/JH4IqimdwPBayrW7aIOlMpDuJVk4lYJ5/YU=; b=bgneGRXfW5SIOpl12VWfezjfsCzFgGa2cyQ/CEyBO9I+BoAyj0l5dANWhLMcb/WRin 6fI3oh0and4BLSikez1XuPNcJpghw6QAlqJeOVCLvzGfuumGwzDEfkypf56DPSRBWUGi 1MieP1vjpsgqCD1ows3H+x8nKEO0levkp7KkoZTLqPfZBwqGrEaRB/xw7N0mvLgUAHkL SmGxjw1GritszTHh01J6Erm7qRlca2JKcdZZxrCcPscniug7QGS/YJZvFpC/+npDm6d7 A/C4CArllJY3p6Gsc/JlqX7zkt8QUL0M1TKYps8dtDzJDTVnzXzmI3WuUpGEYSbthizD UOIw== X-Gm-Message-State: AOAM533Nwtgbh7/ZpydITl7twImfvOgRrj8xwtaeAhuzC7VZ0xOO+BvO Q9kcLC817LfjhWmMfHbGzWXKKjfVsJCMjtsGJkY= X-Received: by 2002:a17:907:60cf:: with SMTP id hv15mr4127275ejc.702.1643314879801; Thu, 27 Jan 2022 12:21:19 -0800 (PST) MIME-Version: 1.0 References: <20220126080947.4529-1-yangyicong@hisilicon.com> <20220126080947.4529-3-yangyicong@hisilicon.com> In-Reply-To: From: Barry Song <21cnbao@gmail.com> Date: Fri, 28 Jan 2022 09:21:08 +1300 Message-ID: Subject: Re: [PATCH v2 2/2] sched/fair: Scan cluster before scanning LLC in wake-up path To: "Gautham R. Shenoy" Cc: Yicong Yang , Peter Zijlstra , Ingo Molnar , Juri Lelli , Vincent Guittot , Tim Chen , LKML , LAK , Dietmar Eggemann , Steven Rostedt , Ben Segall , Daniel Bristot de Oliveira , prime.zeng@huawei.com, Jonathan Cameron , ego@linux.vnet.ibm.com, Srikar Dronamraju , Linuxarm , Barry Song , Guodong Xu Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 28, 2022 at 4:41 AM Gautham R. Shenoy wrote: > > On Wed, Jan 26, 2022 at 04:09:47PM +0800, Yicong Yang wrote: > > From: Barry Song > > > > For platforms having clusters like Kunpeng920, CPUs within the same > > cluster have lower latency when synchronizing and accessing shared > > resources like cache. Thus, this patch tries to find an idle cpu > > within the cluster of the target CPU before scanning the whole LLC > > to gain lower latency. > > > > Note neither Kunpeng920 nor x86 Jacobsville supports SMT, so this > > patch doesn't consider SMT for this moment. > > > > Testing has been done on Kunpeng920 by pinning tasks to one numa > > and two numa. On Kunpeng920, Each numa has 8 clusters and each > > cluster has 4 CPUs. > > > > With this patch, We noticed enhancement on tbench within one > > numa or cross two numa. > > > > On numa 0: > > 5.17-rc1 patched > > Hmean 1 324.73 ( 0.00%) 378.01 * 16.41%* > > Hmean 2 645.36 ( 0.00%) 754.63 * 16.93%* > > Hmean 4 1302.09 ( 0.00%) 1507.54 * 15.78%* > > Hmean 8 2612.03 ( 0.00%) 2982.57 * 14.19%* > > Hmean 16 5307.12 ( 0.00%) 5886.66 * 10.92%* > > Hmean 32 9354.22 ( 0.00%) 9908.13 * 5.92%* > > Hmean 64 7240.35 ( 0.00%) 7278.78 * 0.53%* > > Hmean 128 6186.40 ( 0.00%) 6187.85 ( 0.02%) > > > > On numa 0-1: > > 5.17-rc1 patched > > Hmean 1 320.01 ( 0.00%) 378.44 * 18.26%* > > Hmean 2 643.85 ( 0.00%) 752.52 * 16.88%* > > Hmean 4 1287.36 ( 0.00%) 1505.62 * 16.95%* > > Hmean 8 2564.60 ( 0.00%) 2955.29 * 15.23%* > > Hmean 16 5195.69 ( 0.00%) 5814.74 * 11.91%* > > Hmean 32 9769.16 ( 0.00%) 10872.63 * 11.30%* > > Hmean 64 15952.50 ( 0.00%) 17281.98 * 8.33%* > > Hmean 128 13113.77 ( 0.00%) 13895.20 * 5.96%* > > Hmean 256 10997.59 ( 0.00%) 11244.69 * 2.25%* > > Hmean 512 14623.60 ( 0.00%) 15526.25 * 6.17%* > > > > This will also help to improve the MySQL. With MySQL server > > running on numa 0 and client running on numa 1, both QPS and > > latency is imporved on read-write case: > > 5.17-rc1 patched > > QPS-16threads 143333.2633 145077.4033(+1.22%) > > QPS-24threads 195085.9367 202719.6133(+3.91%) > > QPS-32threads 241165.6867 249020.74(+3.26%) > > QPS-64threads 244586.8433 253387.7567(+3.60%) > > avg-lat-16threads 2.23 2.19(+1.19%) > > avg-lat-24threads 2.46 2.36(+3.79%) > > avg-lat-36threads 2.66 2.57(+3.26%) > > avg-lat-64threads 5.23 5.05(+3.44%) > > > > Tested-by: Yicong Yang > > Signed-off-by: Barry Song > > Signed-off-by: Yicong Yang > > --- > > kernel/sched/fair.c | 46 +++++++++++++++++++++++++++++++++++++++++---- > > 1 file changed, 42 insertions(+), 4 deletions(-) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 5146163bfabb..2f84a933aedd 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -6262,12 +6262,46 @@ static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd > > > > #endif /* CONFIG_SCHED_SMT */ > > > > +#ifdef CONFIG_SCHED_CLUSTER > > +/* > > + * Scan the cluster domain for idle CPUs and clear cluster cpumask after scanning > > + */ > > +static inline int scan_cluster(struct task_struct *p, int prev_cpu, int target) > > +{ > > + struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask); > > + struct sched_domain *sd = rcu_dereference(per_cpu(sd_cluster, target)); > > + int cpu, idle_cpu; > > + > > + /* TODO: Support SMT case while a machine with both cluster and SMT born */ > > + if (!sched_smt_active() && sd) { > > + for_each_cpu_and(cpu, cpus, sched_domain_span(sd)) { > > + idle_cpu = __select_idle_cpu(cpu, p); > > + if ((unsigned int)idle_cpu < nr_cpumask_bits) > > + return idle_cpu; > > + } > > + > > + /* Don't ping-pong tasks in and out cluster frequently */ > > + if (cpus_share_resources(target, prev_cpu)) > > + return target; > > We reach here when there aren't any idle CPUs within the > cluster. However there might be idle CPUs in the MC domain. Is a busy > @target preferable to a potentially idle CPU within the larger domain > ? Hi Gautham, My benchmark showed some performance regression while load was medium or above if we grabbed idle cpu in and out the cluster. it turned out the regression disappeared if we blocked the ping-pong. so the logic here is that if we have scanned and found an idle cpu within the cluster before, we don't let the task jumping back and forth frequently as cache synchronization is higher cost. but the code still allows scanning out of the cluster if we haven't packed waker and wakee together yet. it might not be a universal win in all kinds of workload. we saw tbench, mysql benefit from the whole change. but pgbench seems not always. so we are still on the way to make possible further tuning here. > > > -- > Thanks and Regards > gautham. Thanks Barry