From nobody Sun Apr 19 13:55:01 2026 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 81E22C433EF for ; Thu, 30 Jun 2022 06:56:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232871AbiF3G44 (ORCPT ); Thu, 30 Jun 2022 02:56:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232400AbiF3G4x (ORCPT ); Thu, 30 Jun 2022 02:56:53 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD9B832069 for ; Wed, 29 Jun 2022 23:56:51 -0700 (PDT) Received: from canpemm500009.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4LYTbD10nmzhYxS; Thu, 30 Jun 2022 14:54:32 +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, 30 Jun 2022 14:56:49 +0800 From: Yicong Yang To: , , , , , , , CC: , , , , , , , , , , <21cnbao@gmail.com>, , , , , , , Subject: [PATCH v5 1/2] sched: Add per_cpu cluster domain info and cpus_share_lowest_cache API Date: Thu, 30 Jun 2022 14:55:26 +0800 Message-ID: <20220630065527.38544-2-yangyicong@hisilicon.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20220630065527.38544-1-yangyicong@hisilicon.com> References: <20220630065527.38544-1-yangyicong@hisilicon.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.67.164.66] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) 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 Content-Type: text/plain; charset="utf-8" From: Barry Song Add per-cpu cluster domain info and cpus_share_lowest_cache() API. This is the preparation for the optimization of select_idle_cpu() on platforms with cluster scheduler level. Tested-by: K Prateek Nayak Signed-off-by: Barry Song Signed-off-by: Yicong Yang Reviewed-by: Gautham R. Shenoy Reviewed-by: Tim Chen --- include/linux/sched/sd_flags.h | 7 +++++++ include/linux/sched/topology.h | 8 +++++++- kernel/sched/core.c | 12 ++++++++++++ kernel/sched/sched.h | 2 ++ kernel/sched/topology.c | 15 +++++++++++++++ 5 files changed, 43 insertions(+), 1 deletion(-) diff --git a/include/linux/sched/sd_flags.h b/include/linux/sched/sd_flags.h index 57bde66d95f7..42ed454e8b18 100644 --- a/include/linux/sched/sd_flags.h +++ b/include/linux/sched/sd_flags.h @@ -109,6 +109,13 @@ SD_FLAG(SD_ASYM_CPUCAPACITY_FULL, SDF_SHARED_PARENT | = SDF_NEEDS_GROUPS) */ SD_FLAG(SD_SHARE_CPUCAPACITY, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS) =20 +/* + * Domain members share CPU cluster (LLC tags or L2 cache) + * + * NEEDS_GROUPS: Clusters are shared between groups. + */ +SD_FLAG(SD_CLUSTER, SDF_NEEDS_GROUPS) + /* * Domain members share CPU package resources (i.e. caches) * diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h index 816df6cc444e..c0d21667ddf3 100644 --- a/include/linux/sched/topology.h +++ b/include/linux/sched/topology.h @@ -45,7 +45,7 @@ static inline int cpu_smt_flags(void) #ifdef CONFIG_SCHED_CLUSTER static inline int cpu_cluster_flags(void) { - return SD_SHARE_PKG_RESOURCES; + return SD_CLUSTER | SD_SHARE_PKG_RESOURCES; } #endif =20 @@ -179,6 +179,7 @@ cpumask_var_t *alloc_sched_domains(unsigned int ndoms); void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms); =20 bool cpus_share_cache(int this_cpu, int that_cpu); +bool cpus_share_lowest_cache(int this_cpu, int that_cpu); =20 typedef const struct cpumask *(*sched_domain_mask_f)(int cpu); typedef int (*sched_domain_flags_f)(void); @@ -232,6 +233,11 @@ static inline bool cpus_share_cache(int this_cpu, int = that_cpu) return true; } =20 +static inline bool cpus_share_lowest_cache(int this_cpu, int that_cpu) +{ + return true; +} + #endif /* !CONFIG_SMP */ =20 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d3e2c5a7c1b7..2e6816aeaa2b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3808,6 +3808,18 @@ bool cpus_share_cache(int this_cpu, int that_cpu) return per_cpu(sd_llc_id, this_cpu) =3D=3D per_cpu(sd_llc_id, that_cpu); } =20 +/* + * Whether CPUs are share lowest cache, which means LLC on non-cluster + * machines and LLC tag or L2 on machines with clusters. + */ +bool cpus_share_lowest_cache(int this_cpu, int that_cpu) +{ + if (this_cpu =3D=3D that_cpu) + return true; + + return per_cpu(sd_lowest_cache_id, this_cpu) =3D=3D per_cpu(sd_lowest_cac= he_id, that_cpu); +} + static inline bool ttwu_queue_cond(int cpu) { /* diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 02c970501295..767e637ceb5a 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1753,7 +1753,9 @@ static inline struct sched_domain *lowest_flag_domain= (int cpu, int flag) DECLARE_PER_CPU(struct sched_domain __rcu *, sd_llc); DECLARE_PER_CPU(int, sd_llc_size); DECLARE_PER_CPU(int, sd_llc_id); +DECLARE_PER_CPU(int, sd_lowest_cache_id); DECLARE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared); +DECLARE_PER_CPU(struct sched_domain __rcu *, sd_cluster); DECLARE_PER_CPU(struct sched_domain __rcu *, sd_numa); DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing); DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity); diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 8739c2a5a54e..8ab27c0d6d1f 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -664,6 +664,8 @@ static void destroy_sched_domains(struct sched_domain *= sd) DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc); DEFINE_PER_CPU(int, sd_llc_size); DEFINE_PER_CPU(int, sd_llc_id); +DEFINE_PER_CPU(int, sd_lowest_cache_id); +DEFINE_PER_CPU(struct sched_domain __rcu *, sd_cluster); DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared); DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa); DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing); @@ -689,6 +691,18 @@ static void update_top_cache_domain(int cpu) per_cpu(sd_llc_id, cpu) =3D id; rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds); =20 + sd =3D lowest_flag_domain(cpu, SD_CLUSTER); + if (sd) + id =3D cpumask_first(sched_domain_span(sd)); + rcu_assign_pointer(per_cpu(sd_cluster, cpu), sd); + + /* + * This assignment should be placed after the sd_llc_id as + * we want this id equals to cluster id on cluster machines + * but equals to LLC id on non-Cluster machines. + */ + per_cpu(sd_lowest_cache_id, cpu) =3D id; + sd =3D lowest_flag_domain(cpu, SD_NUMA); rcu_assign_pointer(per_cpu(sd_numa, cpu), sd); =20 @@ -1532,6 +1546,7 @@ static struct cpumask ***sched_domains_numa_masks; */ #define TOPOLOGY_SD_FLAGS \ (SD_SHARE_CPUCAPACITY | \ + SD_CLUSTER | \ SD_SHARE_PKG_RESOURCES | \ SD_NUMA | \ SD_ASYM_PACKING) --=20 2.24.0 From nobody Sun Apr 19 13:55:01 2026 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 72588C433EF for ; Thu, 30 Jun 2022 06:57:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232495AbiF3G47 (ORCPT ); Thu, 30 Jun 2022 02:56:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232615AbiF3G4y (ORCPT ); Thu, 30 Jun 2022 02:56:54 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F0AE32ED5 for ; Wed, 29 Jun 2022 23:56:52 -0700 (PDT) Received: from canpemm500009.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4LYTYq2ZzYzTgKs; Thu, 30 Jun 2022 14:53:19 +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, 30 Jun 2022 14:56:49 +0800 From: Yicong Yang To: , , , , , , , CC: , , , , , , , , , , <21cnbao@gmail.com>, , , , , , , Subject: [PATCH v5 2/2] sched/fair: Scan cluster before scanning LLC in wake-up path Date: Thu, 30 Jun 2022 14:55:27 +0800 Message-ID: <20220630065527.38544-3-yangyicong@hisilicon.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20220630065527.38544-1-yangyicong@hisilicon.com> References: <20220630065527.38544-1-yangyicong@hisilicon.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.67.164.66] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) 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 Content-Type: text/plain; charset="utf-8" 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 =20 #endif /* CONFIG_SCHED_SMT */ =20 +#ifdef CONFIG_SCHED_CLUSTER +/* + * Scan the cluster domain for idle CPUs and clear cluster cpumask after s= canning + */ +static inline int scan_cluster(struct task_struct *p, struct cpumask *cpus, + int target, int *nr) +{ + struct sched_domain *sd =3D 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 =3D __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, st= ruct sched_domain *sd, bool } } =20 + idle_cpu =3D 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 =3D select_idle_core(p, cpu, cpus, &idle_cpu); @@ -6390,7 +6428,7 @@ static int select_idle_cpu(struct task_struct *p, str= uct sched_domain *sd, bool return i; =20 } else { - if (!--nr) + if (--nr <=3D 0) return -1; idle_cpu =3D __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 !=3D target && cpus_share_cache(prev, target) && + if (prev !=3D 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 =3D prev; if (recent_used_cpu !=3D prev && recent_used_cpu !=3D 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_cp= u)) && cpumask_test_cpu(p->recent_used_cpu, p->cpus_ptr) && asym_fits_capacity(task_util, recent_used_cpu)) { --=20 2.24.0