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 6FF7DC433EF for ; Thu, 9 Jun 2022 12:07:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241879AbiFIMHs (ORCPT ); Thu, 9 Jun 2022 08:07:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236999AbiFIMHd (ORCPT ); Thu, 9 Jun 2022 08:07:33 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8AA7C26446C for ; Thu, 9 Jun 2022 05:07:31 -0700 (PDT) Received: from canpemm500009.china.huawei.com (unknown [172.30.72.57]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4LJjTv4hs4z1GCYh; Thu, 9 Jun 2022 20:05:39 +0800 (CST) Received: from localhost.localdomain (10.67.164.66) 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, 9 Jun 2022 20:07:29 +0800 From: Yicong Yang To: , , , , , , , CC: , , , , , , , , , , <21cnbao@gmail.com>, , , , Subject: [PATCH v4 2/2] sched/fair: Scan cluster before scanning LLC in wake-up path Date: Thu, 9 Jun 2022 20:06:22 +0800 Message-ID: <20220609120622.47724-3-yangyicong@hisilicon.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20220609120622.47724-1-yangyicong@hisilicon.com> References: <20220609120622.47724-1-yangyicong@hisilicon.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.67.164.66] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) 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 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: 5.19-rc1 patched Hmean 1 350.27 ( 0.00%) 406.88 * 16.16%* Hmean 2 702.01 ( 0.00%) 808.22 * 15.13%* Hmean 4 1405.14 ( 0.00%) 1614.34 * 14.89%* Hmean 8 2830.53 ( 0.00%) 3169.02 * 11.96%* Hmean 16 5597.95 ( 0.00%) 6224.20 * 11.19%* Hmean 32 10537.38 ( 0.00%) 10524.97 * -0.12%* Hmean 64 8366.04 ( 0.00%) 8437.41 * 0.85%* Hmean 128 7060.87 ( 0.00%) 7150.25 * 1.27%* On numa 0-1: 5.19-rc1 patched Hmean 1 346.11 ( 0.00%) 408.47 * 18.02%* Hmean 2 693.34 ( 0.00%) 805.78 * 16.22%* Hmean 4 1384.96 ( 0.00%) 1602.49 * 15.71%* Hmean 8 2699.45 ( 0.00%) 3069.98 * 13.73%* Hmean 16 5327.11 ( 0.00%) 5688.19 * 6.78%* Hmean 32 10019.10 ( 0.00%) 11862.56 * 18.40%* Hmean 64 13850.57 ( 0.00%) 17748.54 * 28.14%* Hmean 128 12498.25 ( 0.00%) 15541.59 * 24.35%* Hmean 256 11195.77 ( 0.00%) 13854.06 * 23.74%* Tested-by: Yicong Yang Signed-off-by: Barry Song Signed-off-by: Yicong Yang --- 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 77b2048a9326..6d173e196ad3 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6327,6 +6327,40 @@ 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) + break; + + 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 @@ -6375,6 +6409,10 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool time = cpu_clock(this); } + 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); @@ -6382,7 +6420,7 @@ 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) @@ -6481,7 +6519,7 @@ 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_resources(prev, target) && (available_idle_cpu(prev) || sched_idle_cpu(prev)) && asym_fits_capacity(task_util, prev)) return prev; @@ -6507,7 +6545,7 @@ 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_resources(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)) { -- 2.24.0