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 C7294C433EF for ; Thu, 14 Jul 2022 09:41:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238358AbiGNJlK (ORCPT ); Thu, 14 Jul 2022 05:41:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230443AbiGNJlI (ORCPT ); Thu, 14 Jul 2022 05:41:08 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 97D1D46D9A for ; Thu, 14 Jul 2022 02:41:06 -0700 (PDT) Received: from canpemm500009.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Lk8Xd5XqRzVfwp; Thu, 14 Jul 2022 17:37:21 +0800 (CST) Received: from [10.67.102.169] (10.67.102.169) by canpemm500009.china.huawei.com (7.192.105.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 14 Jul 2022 17:41:04 +0800 CC: , , , , , , , , , <21cnbao@gmail.com>, , , , , , , , Yicong Yang Subject: Re: [PATCH v5 2/2] sched/fair: Scan cluster before scanning LLC in wake-up path To: , , , , , , , References: <20220630065527.38544-1-yangyicong@hisilicon.com> <20220630065527.38544-3-yangyicong@hisilicon.com> From: Yicong Yang Message-ID: <3d612766-592f-760f-ca43-4ea2257a8bb2@huawei.com> Date: Thu, 14 Jul 2022 17:41:04 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: <20220630065527.38544-3-yangyicong@hisilicon.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.102.169] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500009.china.huawei.com (7.192.105.203) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, a friendly ping.. On 2022/6/30 14:55, 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: > tip/core patched > Hmean 1 345.89 ( 0.00%) 393.96 * 13.90%* > Hmean 2 697.77 ( 0.00%) 786.04 * 12.65%* > Hmean 4 1392.51 ( 0.00%) 1570.26 * 12.76%* > Hmean 8 2800.61 ( 0.00%) 3083.98 * 10.12%* > Hmean 16 5514.27 ( 0.00%) 6116.00 * 10.91%* > Hmean 32 10869.81 ( 0.00%) 10782.98 * -0.80%* > Hmean 64 8315.22 ( 0.00%) 8519.84 * 2.46%* > Hmean 128 6324.47 ( 0.00%) 7159.35 * 13.20%* > > On numa 0-1: > tip/core patched > Hmean 1 348.68 ( 0.00%) 387.91 * 11.25%* > Hmean 2 693.57 ( 0.00%) 774.91 * 11.73%* > Hmean 4 1369.26 ( 0.00%) 1475.48 * 7.76%* > Hmean 8 2772.99 ( 0.00%) 2984.61 * 7.63%* > Hmean 16 4825.83 ( 0.00%) 5873.13 * 21.70%* > Hmean 32 10250.32 ( 0.00%) 11688.06 * 14.03%* > Hmean 64 16309.51 ( 0.00%) 19889.48 * 21.95%* > Hmean 128 13022.32 ( 0.00%) 16005.64 * 22.91%* > Hmean 256 11335.79 ( 0.00%) 13821.74 * 21.93%* > > Tested-by: Yicong Yang > Signed-off-by: Barry Song > Signed-off-by: Yicong Yang > Reviewed-by: Tim Chen > --- > kernel/sched/fair.c | 44 +++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 41 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index f80ae86bb404..dff5dec0d792 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6323,6 +6323,40 @@ 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, struct cpumask *cpus, > + int target, int *nr) > +{ > + struct sched_domain *sd = rcu_dereference(per_cpu(sd_cluster, target)); > + int cpu, idle_cpu; > + > + /* TODO: Support SMT system with cluster topology */ > + if (!sched_smt_active() && sd) { > + for_each_cpu_and(cpu, cpus, sched_domain_span(sd)) { > + if (!--*nr) > + return -1; > + > + idle_cpu = __select_idle_cpu(cpu, p); > + if ((unsigned int)idle_cpu < nr_cpumask_bits) > + return idle_cpu; > + } > + > + cpumask_andnot(cpus, cpus, sched_domain_span(sd)); > + } > + > + return -1; > +} > +#else > +static inline int scan_cluster(struct task_struct *p, struct cpumask *cpus, > + int target, int *nr) > +{ > + return -1; > +} > +#endif > + > /* > * Scan the LLC domain for idle CPUs; this is dynamically regulated by > * comparing the average scan cost (tracked in sd->avg_scan_cost) against the > @@ -6383,6 +6417,10 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool > } > } > > + idle_cpu = scan_cluster(p, cpus, target, &nr); > + if ((unsigned int)idle_cpu < nr_cpumask_bits) > + return idle_cpu; > + > for_each_cpu_wrap(cpu, cpus, target + 1) { > if (has_idle_core) { > i = select_idle_core(p, cpu, cpus, &idle_cpu); > @@ -6390,7 +6428,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool > return i; > > } else { > - if (!--nr) > + if (--nr <= 0) > return -1; > idle_cpu = __select_idle_cpu(cpu, p); > if ((unsigned int)idle_cpu < nr_cpumask_bits) > @@ -6489,7 +6527,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) > /* > * If the previous CPU is cache affine and idle, don't be stupid: > */ > - if (prev != target && cpus_share_cache(prev, target) && > + if (prev != target && cpus_share_lowest_cache(prev, target) && > (available_idle_cpu(prev) || sched_idle_cpu(prev)) && > asym_fits_capacity(task_util, prev)) > return prev; > @@ -6515,7 +6553,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) > p->recent_used_cpu = prev; > if (recent_used_cpu != prev && > recent_used_cpu != target && > - cpus_share_cache(recent_used_cpu, target) && > + cpus_share_lowest_cache(recent_used_cpu, target) && > (available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) && > cpumask_test_cpu(p->recent_used_cpu, p->cpus_ptr) && > asym_fits_capacity(task_util, recent_used_cpu)) { >