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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F3FFFC43334 for ; Thu, 9 Jun 2022 22:48:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Date:Cc:To:From:Subject:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ZkGfdnFDmMhE3sWU8PeHtba/LPxTnsugY5sJiBlIcwQ=; b=jpGsST6+IeY5b1 XPxcdAyIpHP/Qw0v4GFumKCSBO8xCESl0oEbR7fjc0VfHw9sBlUraJLwP5PmGuYxcM5g4YYVioNrY Fbxcj1yDcijHbkxG9X4oX73kB/k4U+FM0k3apV9xIn1n0solAw5M79W9EGyRRkCEt2G0s0+Vh9A4v iDMhlxUn+abxGv5hryo+vCTBMiepbAaRar+BxQEbj7pL3Ci3D7KJR4RQ+7aY4ANJIe4EL1VfnzG9J esApa0/9MJJ7RU3utLE4nEeGew9KBaApRYPhznzKT58YnMJY1OaWm+Hmewv3JDt2+h4eZX7wEB+2E tvxunSG8CB1x1SKqoH7w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nzQvo-004SyE-E2; Thu, 09 Jun 2022 22:47:12 +0000 Received: from mga11.intel.com ([192.55.52.93]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nzQvl-004Sw1-2H for linux-arm-kernel@lists.infradead.org; Thu, 09 Jun 2022 22:47:10 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1654814829; x=1686350829; h=message-id:subject:from:to:cc:date:in-reply-to: references:mime-version:content-transfer-encoding; bh=Wl02wZmJSesfgSxQC+StZTeRj2quJv7mh4gaob/Tt7w=; b=XZjamStHm8pfSnb1+ZPWpnkKK7jbypA6atIvPHPkIQbF04/86qt43bOI NnOhwwv9Az4Pj17Lw9rTZV6MswcVQ8rUW9QtaqgJO451BckqeRaYOzMfa HHJWR0JPeSbdU2M8PGYR2F3yR83Gl1KNh2Cp0wGYh0wdWtAVBa8fV+pPE H8ynzV6ThstT61HqODHt3fWzG4KnqPWz2tJho3BR9OXd0sQoFVGC/Dtpo Zz3JrF7QgsBy/QnPBdkgIG7sHoIYirXpnwlxkWOqT36ExwPH3DL8PINly N0oTIWTPW3KaoGNmnKR22uM2wB8jKSH+wbKrudh1a14bCrS0JjD6uJQFB Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10373"; a="274969819" X-IronPort-AV: E=Sophos;i="5.91,288,1647327600"; d="scan'208";a="274969819" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jun 2022 15:47:05 -0700 X-IronPort-AV: E=Sophos;i="5.91,288,1647327600"; d="scan'208";a="585850105" Received: from schen9-mobl.amr.corp.intel.com ([10.212.167.148]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jun 2022 15:47:04 -0700 Message-ID: Subject: Re: [PATCH v4 2/2] sched/fair: Scan cluster before scanning LLC in wake-up path From: Tim Chen To: 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, guodong.xu@linaro.org, hesham.almatary@huawei.com, john.garry@huawei.com, shenyang39@huawei.com Date: Thu, 09 Jun 2022 15:47:03 -0700 In-Reply-To: <20220609120622.47724-3-yangyicong@hisilicon.com> References: <20220609120622.47724-1-yangyicong@hisilicon.com> <20220609120622.47724-3-yangyicong@hisilicon.com> User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220609_154709_206656_63EAD552 X-CRM114-Status: GOOD ( 28.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 2022-06-09 at 20:06 +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: > 5.19-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%* Yicong, Have you tried any workload where tasks don't share data with each other but have sleep/wakeup? That's the case where we actually want to spread the tasks out among the clusters to void contention for L2 cache. Will be nice to make sure there's no regression there for such workload. Code itself looks good. Reviewed-by: Tim Chen > > 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)) { _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel