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 00025C43334 for ; Fri, 10 Jun 2022 06:41:08 +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:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:CC:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=vSrsbinK5xf4/VUmU/yLVZ4kvo3Gxv37Et0xXwLOYF8=; b=KXbQt4Qgd+w2wGrKeHP31CfLhT ft0tpLiqfmlt6DOUUYV4WI4ELI0cxI+2RDeiBdTOCP2ATq9kUkMpSJDUO/HksZ+o7fUZlhTLstifp pxe4hLJjBpyiR+V175/IK0JKQvWdqc2xbKpjxPv0uMG0KigWm3wRRov7tAjgoN6zs0RxwncKWXjZW D5PsCWMz3G54wl6A8jNVFp1l8vwwA0QwdAukRbQIvs5Uw0/rL91+dWEOxldQuNwkjvrFOBckMbp77 cEqotTOMDrxkBxXLu/mDWvX1AjY1Z+y0EkLQFO1gJBai4Fz8digzIMokfdMC48vMMNUcCUN+xtVsL uiggxH7A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nzYJD-006CN4-PS; Fri, 10 Jun 2022 06:39:51 +0000 Received: from szxga08-in.huawei.com ([45.249.212.255]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nzYJ7-006CJX-W6 for linux-arm-kernel@lists.infradead.org; Fri, 10 Jun 2022 06:39:48 +0000 Received: from canpemm500009.china.huawei.com (unknown [172.30.72.57]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4LKB973Zxmz1K97w; Fri, 10 Jun 2022 14:37:47 +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; Fri, 10 Jun 2022 14:39:38 +0800 CC: , , , , , , , , , <21cnbao@gmail.com>, , , , , Chen Yu Subject: Re: [PATCH v4 2/2] sched/fair: Scan cluster before scanning LLC in wake-up path To: Tim Chen , Yicong Yang , , , , , , , References: <20220609120622.47724-1-yangyicong@hisilicon.com> <20220609120622.47724-3-yangyicong@hisilicon.com> From: Yicong Yang Message-ID: <4ab2c422-04ae-3199-ae2a-357c3270cd05@huawei.com> Date: Fri, 10 Jun 2022 14:39:38 +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: X-Originating-IP: [10.67.102.169] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500009.china.huawei.com (7.192.105.203) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220609_233946_449524_D0E91557 X-CRM114-Status: GOOD ( 21.77 ) 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 2022/6/10 6:47, Tim Chen wrote: > 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. > Any certain workload you'd like me test? I'm willing to do :) I've tested this patch with MySQL as well (like in v2). This won't hurt the MySQL case with SIS_PROP but observed some improvement with SIS_UTIL posted in [1]. We leverage the nr to suppress redundant scanning in the current approach and seems SIS_UTIL is more efficient in this case. 5.19-rc1 patched patched+SIS_UTIL[1] TPS-16threads 6215.11 6172.74 (-0.68%) 6217.33 (0.04%) QPS-16threads 124302.21 123454.68 (-0.68%) 124346.52 (0.04%) avg-lat-16threads 2.57 2.59 (-0.65%) 2.57 (0.00%) TPS-24threads 8726.40 8690.87 (-0.41%) 8833.08 (1.22%) QPS-24threads 174527.88 173817.42 (-0.41%) 176661.54 (1.21%) avg-lat-24threads 2.75 2.76 (-0.36%) 2.71 (1.33%) TPS-32threads 9555.42 9514.86 (-0.42%) 10010.87 (4.77%) QPS-32threads 191108.37 190297.28 (-0.42%) 200217.35 (4.55%) avg-lat-32threads 3.35 3.36 (-0.30%) 3.20 (4.58%) TPS-64threads 10290.10 10324.75 (0.34%) 10819.77 (5.15%) QPS-64threads 205802.05 206494.95 (0.34%) 216395.40 (4.90%) avg-lat-64threads 6.22 6.20 (0.38%) 5.92 (4.88%) > Code itself looks good. > > Reviewed-by: Tim Chen > Thanks. [1] https://lore.kernel.org/lkml/20220428182442.659294-1-yu.c.chen@intel.com/ >> >> 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