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 ADFE5C433EF for ; Thu, 27 Jan 2022 02:30:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235135AbiA0Ca0 (ORCPT ); Wed, 26 Jan 2022 21:30:26 -0500 Received: from mga17.intel.com ([192.55.52.151]:57192 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229518AbiA0CaZ (ORCPT ); Wed, 26 Jan 2022 21:30:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1643250625; x=1674786625; h=message-id:subject:from:to:cc:date:in-reply-to: references:mime-version:content-transfer-encoding; bh=ApbpMHUzsnomU7MZGBq6xvbQoWFL78b++WK0hDLOEhI=; b=iGMxhntjRN/hoiYBtci327sOjOQYk4/2aaAX67UdyMNXvmf2XB/THI7F PlS89xYE5fifaTii7yqEkMw+KH+WlMWrDQLfCb1pfZOJ5VQlw2k+3Qn4X tDRZwbpsaa2p98fkjShP4Pvso9KY96SQKnkcNq9b4k3fHnNUARfyy9DAi slhhaTZT/PSEkVleY6iDSoQUbjLXNwPKIClGlSLXydPq2C1Sdrgtrbg2F ZfMSSpEx6+u+wcZIkMcWQUtgLuBC4VQzwl7Gq0BUhBPYpfaDpa6+k3ofd ayBTPH7FeBtV2ZSbg3NCjOOpcBJuXELQAk1WmS6WSEJ6gnutQi7ojJF2Y w==; X-IronPort-AV: E=McAfee;i="6200,9189,10239"; a="227395894" X-IronPort-AV: E=Sophos;i="5.88,319,1635231600"; d="scan'208";a="227395894" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jan 2022 18:30:25 -0800 X-IronPort-AV: E=Sophos;i="5.88,319,1635231600"; d="scan'208";a="532958831" Received: from schen9-mobl.amr.corp.intel.com ([10.212.144.230]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jan 2022 18:30:24 -0800 Message-ID: <95f82bf3524289bfbcaeee6e83b6dac48ed07f25.camel@linux.intel.com> Subject: Re: [PATCH v2 2/2] sched/fair: Scan cluster before scanning LLC in wake-up path From: Tim Chen To: Yicong Yang , Yicong Yang , peterz@infradead.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, gautham.shenoy@amd.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, prime.zeng@huawei.com, jonathan.cameron@huawei.com, ego@linux.vnet.ibm.com, srikar@linux.vnet.ibm.com, linuxarm@huawei.com, 21cnbao@gmail.com, song.bao.hua@hisilicon.com, guodong.xu@linaro.org Date: Wed, 26 Jan 2022 18:30:23 -0800 In-Reply-To: References: <20220126080947.4529-1-yangyicong@hisilicon.com> <20220126080947.4529-3-yangyicong@hisilicon.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2022-01-27 at 10:02 +0800, Yicong Yang wrote: > On 2022/1/27 9:14, Tim Chen wrote: > > On Wed, 2022-01-26 at 16:09 +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 */ > > > > This is probably a clearer comment > > > > /* TODO: Support SMT system with cluster topology */ > > > > > + if (!sched_smt_active() && sd) { > > > + for_each_cpu_and(cpu, cpus, sched_domain_span(sd)) { > > > + idle_cpu = __select_idle_cpu(cpu, p); > > > */ > > > -static int select_idle_cpu(struct task_struct *p, struct > > > sched_domain *sd, bool has_idle_core, int target) > > > +static int select_idle_cpu(struct task_struct *p, struct > > > sched_domain *sd, bool has_idle_core, int prev_cpu, int target) > > > { > > > struct cpumask *cpus = > > > this_cpu_cpumask_var_ptr(select_idle_mask); > > > int i, cpu, idle_cpu = -1, nr = INT_MAX; > > > @@ -6282,6 +6316,10 @@ static int select_idle_cpu(struct > > > task_struct > > > *p, struct sched_domain *sd, bool > > > > > > cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr); > > > > > > + idle_cpu = scan_cluster(p, prev_cpu, target); > > > > Shouldn't "cpus" from > > > > cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr); > > > > be passed to scan_cluster, to make sure that the cpu returned is > > in the affinity mask of the task? I don't see p->cpus_ptr > > being checked in scan_cluster to make sure the cpu found is in the > > affinity mask. > > > > The cpus scanned in scan_cluster() is the intersection of > select_idle_mask and sched_domain_span(cluster_sd), and > we limited the select_idle_mask in the tasks' affinity mask > before we enter scan_cluster() here. Ah, I missed the fact that cpus point to the select_idle_mask. Thanks. Tim