From patchwork Tue Feb 6 19:23:05 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Guittot X-Patchwork-Id: 127079 Delivered-To: patch@linaro.org Received: by 10.46.124.24 with SMTP id x24csp3208448ljc; Tue, 6 Feb 2018 11:23:29 -0800 (PST) X-Google-Smtp-Source: AH8x227FCuZinxFQETbHj+50nFeNsGTUbb6fEnKPdvdaX5pYvKF39ULpvt1GQgKHONxKDCo1cLm4 X-Received: by 10.98.147.85 with SMTP id b82mr3439814pfe.203.1517945009817; Tue, 06 Feb 2018 11:23:29 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1517945009; cv=none; d=google.com; s=arc-20160816; b=aCfgLweviwBwlzpHpjMXDL/ntLLGYyWKLUSiJVfGwoSMtaMuctq5ZrguxET9wJIDgO tKFTamXgYzTRp3BEGZIqUDLT7lLkLaZqSsb0vf156MFIYHiw4R3rxkCtKMWUdjS0X0BY sBNI+8JguAebNtIbZpbhesN9yXUIpS6BfQLZrElMU8hCjRkDnEYs17XmzOtS+BriT0G1 C3mwF6TCRTCxVWu7MqofUwVcrrVZlu1ob/Kak2uH4xxrAEDpaD5KomECo/xrBcWgmFO1 OOBoT5v+JbQP8yyFuL9HMeI1MpRHzJmwcgvaVvcBmvheFG9eUULyA75AXTAFQB/kUnU9 nnyA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=kUbIQJiwRrQ1KlVh3SQAgesefSQd+t19mACg/uMzcG0=; b=Xq6PLj4sYSXkQljQ5jyGdmZ8gsYJTpvlXvYmMYRXUvYHFr8gCHN1Br+wWidRXYWuEo UFG2K0lDziG1GIGF6v+mIi/nMLEECJfY7huYo5UVXb3ymvq1JRT1y7t8801dlrs3Esxw 8VmaToTJgXPegRB/PDEMbf1dNtcpzCddDMnx6JRqebEBolmu6XW95QBx9rM9nIDHIgNF zJ3xKCSa6wzU20ifcCKi7wnYew6OycMcX3VJ0Dx/dXCCJNY24uxL/LOOZpBuggrM7Ovh u4EfE69O6G+HTkZkww1h+zufwRdTx8GcWjD/whHn515ye8AKhwCaVeliCruHflKqbdgs BqbQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=gukPqjVf; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id k12si900171pgs.499.2018.02.06.11.23.29; Tue, 06 Feb 2018 11:23:29 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=gukPqjVf; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753229AbeBFTX1 (ORCPT + 18 others); Tue, 6 Feb 2018 14:23:27 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:35010 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751555AbeBFTXV (ORCPT ); Tue, 6 Feb 2018 14:23:21 -0500 Received: by mail-wm0-f65.google.com with SMTP id r78so6064519wme.0 for ; Tue, 06 Feb 2018 11:23:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=kUbIQJiwRrQ1KlVh3SQAgesefSQd+t19mACg/uMzcG0=; b=gukPqjVfGhZgHhx8gm3WK7piQdBrXqfNuBt/20n+sycDq48cZzefT3g7270xoRszlk jZMi6ysPlIjbhgoHsbc0hag7hXspDQz26TQzCxAvTgX3dP75FTJNHrV2C7kfqI5Fyxuy 5piWk8gIPI091va8wYkLVYi4oensvOZfZ6jGQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=kUbIQJiwRrQ1KlVh3SQAgesefSQd+t19mACg/uMzcG0=; b=pAs6OOzw1WJOTMReXEhldB1D3injyxrf4HNnyPTTD/HsD1F5NaDrmxEqQ65IOVTjk/ eeQkMOIQwPGKMuV3l25EA0sMjIZ/UAUyeHa1SrQoIyd3wuMRULTVoaui2nF0wrCf1qtK CCF8pGgy48mDHlY9r/+9XBNz71BmU5CEvzBkDa0iwWpNo3ln4BfpwTeDjTm6MCTrJc9G S+KDBFm4jA+3pDT0nU8ZLE94qezeX1xH8iCw6qQuVqGlWushxbiQzDEDoqAl1/kmsvGj fJs8vaYNLwR2HYXa9Wnr47HI0odoUnKcpHhEC2BcJQhaQ4+62U4D/fXKMs30WqpCwo8+ itPg== X-Gm-Message-State: APf1xPDZUUIUR5gJd6Ngc1qYYHgIu737DVxoFmvwJpJ+7xeZ2hjRFqlf HAItPdFepD5+xfmUc0BUOSAdpQ== X-Received: by 10.80.146.240 with SMTP id l45mr5013404eda.125.1517944999720; Tue, 06 Feb 2018 11:23:19 -0800 (PST) Received: from localhost.localdomain ([2a01:e0a:f:6020:29bb:43dd:7d11:e095]) by smtp.gmail.com with ESMTPSA id s5sm78155eda.60.2018.02.06.11.23.18 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 06 Feb 2018 11:23:18 -0800 (PST) From: Vincent Guittot To: peterz@infradead.org, mingo@kernel.org, linux-kernel@vger.kernel.org, valentin.schneider@arm.com Cc: morten.rasmussen@foss.arm.com, brendan.jackman@arm.com, dietmar.eggemann@arm.com, Vincent Guittot Subject: [PATCH v2 1/3] sched: Stop nohz stats when decayed Date: Tue, 6 Feb 2018 20:23:05 +0100 Message-Id: <1517944987-343-2-git-send-email-vincent.guittot@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1517944987-343-1-git-send-email-vincent.guittot@linaro.org> References: <1517944987-343-1-git-send-email-vincent.guittot@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Stopped the periodic update of blocked load when all idle CPUs have fully decayed. We introduce a new nohz.has_blocked that reflect if some idle CPUs has blocked load that have to be periodiccally updated. nohz.has_blocked is set everytime that a Idle CPU can have blocked load and it is then clear when no more blocked load has been detected during an update. We don't need atomic operation but only to make cure of the right ordering when updating nohz.idle_cpus_mask and nohz.has_blocked. Suggested-by: Peter Zijlstra (Intel) Signed-off-by: Vincent Guittot --- kernel/sched/fair.c | 94 +++++++++++++++++++++++++++++++++++++++++----------- kernel/sched/sched.h | 1 + 2 files changed, 75 insertions(+), 20 deletions(-) -- 2.7.4 diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7af1fa9..b9660b5 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5383,8 +5383,9 @@ decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) static struct { cpumask_var_t idle_cpus_mask; atomic_t nr_cpus; + int has_blocked; /* Idle CPUS has blocked load */ unsigned long next_balance; /* in jiffy units */ - unsigned long next_stats; + unsigned long next_blocked; /* Next update of blocked load in jiffies */ } nohz ____cacheline_aligned; #endif /* CONFIG_NO_HZ_COMMON */ @@ -6951,6 +6952,7 @@ enum fbq_type { regular, remote, all }; #define LBF_DST_PINNED 0x04 #define LBF_SOME_PINNED 0x08 #define LBF_NOHZ_STATS 0x10 +#define LBF_NOHZ_AGAIN 0x20 struct lb_env { struct sched_domain *sd; @@ -7335,8 +7337,6 @@ static void attach_tasks(struct lb_env *env) rq_unlock(env->dst_rq, &rf); } -#ifdef CONFIG_FAIR_GROUP_SCHED - static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq) { if (cfs_rq->load.weight) @@ -7354,11 +7354,14 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq) return true; } +#ifdef CONFIG_FAIR_GROUP_SCHED + static void update_blocked_averages(int cpu) { struct rq *rq = cpu_rq(cpu); struct cfs_rq *cfs_rq, *pos; struct rq_flags rf; + bool done = true; rq_lock_irqsave(rq, &rf); update_rq_clock(rq); @@ -7388,10 +7391,14 @@ static void update_blocked_averages(int cpu) */ if (cfs_rq_is_decayed(cfs_rq)) list_del_leaf_cfs_rq(cfs_rq); + else + done = false; } #ifdef CONFIG_NO_HZ_COMMON rq->last_blocked_load_update_tick = jiffies; + if (done) + rq->has_blocked_load = 0; #endif rq_unlock_irqrestore(rq, &rf); } @@ -7454,6 +7461,8 @@ static inline void update_blocked_averages(int cpu) update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq); #ifdef CONFIG_NO_HZ_COMMON rq->last_blocked_load_update_tick = jiffies; + if (cfs_rq_is_decayed(cfs_rq)) + rq->has_blocked_load = 0; #endif rq_unlock_irqrestore(rq, &rf); } @@ -7789,18 +7798,25 @@ group_type group_classify(struct sched_group *group, return group_other; } -static void update_nohz_stats(struct rq *rq) +static bool update_nohz_stats(struct rq *rq) { #ifdef CONFIG_NO_HZ_COMMON unsigned int cpu = rq->cpu; + if (!rq->has_blocked_load) + return false; + if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask)) - return; + return false; if (!time_after(jiffies, rq->last_blocked_load_update_tick)) - return; + return true; update_blocked_averages(cpu); + + return rq->has_blocked_load; +#else + return false; #endif } @@ -7826,8 +7842,8 @@ static inline void update_sg_lb_stats(struct lb_env *env, for_each_cpu_and(i, sched_group_span(group), env->cpus) { struct rq *rq = cpu_rq(i); - if (env->flags & LBF_NOHZ_STATS) - update_nohz_stats(rq); + if ((env->flags & LBF_NOHZ_STATS) && update_nohz_stats(rq)) + env->flags |= LBF_NOHZ_AGAIN; /* Bias balancing toward cpus of our domain */ if (local_group) @@ -7979,18 +7995,15 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd struct sg_lb_stats *local = &sds->local_stat; struct sg_lb_stats tmp_sgs; int load_idx, prefer_sibling = 0; + int has_blocked = READ_ONCE(nohz.has_blocked); bool overload = false; if (child && child->flags & SD_PREFER_SIBLING) prefer_sibling = 1; #ifdef CONFIG_NO_HZ_COMMON - if (env->idle == CPU_NEWLY_IDLE) { + if (env->idle == CPU_NEWLY_IDLE && has_blocked) env->flags |= LBF_NOHZ_STATS; - - if (cpumask_subset(nohz.idle_cpus_mask, sched_domain_span(env->sd))) - nohz.next_stats = jiffies + msecs_to_jiffies(LOAD_AVG_PERIOD); - } #endif load_idx = get_sd_load_idx(env->sd, env->idle); @@ -8046,6 +8059,15 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd sg = sg->next; } while (sg != env->sd->groups); +#ifdef CONFIG_NO_HZ_COMMON + if ((env->flags & LBF_NOHZ_AGAIN) && + cpumask_subset(nohz.idle_cpus_mask, sched_domain_span(env->sd))) { + + WRITE_ONCE(nohz.next_blocked, + jiffies + msecs_to_jiffies(LOAD_AVG_PERIOD)); + } +#endif + if (env->sd->flags & SD_NUMA) env->fbq_type = fbq_classify_group(&sds->busiest_stat); @@ -9069,6 +9091,8 @@ static void nohz_balancer_kick(struct rq *rq) struct sched_domain *sd; int nr_busy, i, cpu = rq->cpu; unsigned int flags = 0; + unsigned long has_blocked = READ_ONCE(nohz.has_blocked); + unsigned long next_blocked = READ_ONCE(nohz.next_blocked); if (unlikely(rq->idle_balance)) return; @@ -9086,7 +9110,7 @@ static void nohz_balancer_kick(struct rq *rq) if (likely(!atomic_read(&nohz.nr_cpus))) return; - if (time_after(now, nohz.next_stats)) + if (time_after(now, next_blocked) && has_blocked) flags = NOHZ_STATS_KICK; if (time_before(now, nohz.next_balance)) @@ -9207,13 +9231,15 @@ void nohz_balance_enter_idle(int cpu) if (!housekeeping_cpu(cpu, HK_FLAG_SCHED)) return; + rq->has_blocked_load = 1; + if (rq->nohz_tick_stopped) - return; + goto out; /* * If we're a completely isolated CPU, we don't play. */ - if (on_null_domain(cpu_rq(cpu))) + if (on_null_domain(rq)) return; rq->nohz_tick_stopped = 1; @@ -9222,6 +9248,13 @@ void nohz_balance_enter_idle(int cpu) atomic_inc(&nohz.nr_cpus); set_cpu_sd_state_idle(cpu); + +out: + /* + * Each time a cpu enter idle, we assume that it has blocked load and + * enable the periodic update of the load of idle cpus + */ + WRITE_ONCE(nohz.has_blocked, 1); } #else static inline void nohz_balancer_kick(struct rq *rq) { } @@ -9374,6 +9407,16 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) SCHED_WARN_ON((flags & NOHZ_KICK_MASK) == NOHZ_BALANCE_KICK); + /* + * We assume there will be no idle load after this update and clear + * the has_blocked flag. If a cpu enters idle in the mean time, it will + * set the has_blocked flag and trig another update of idle load. + * Because a cpu that becomes idle, is added to idle_cpus_mask before + * setting the flag, we are sure to not clear the state and not + * check the load of an idle cpu. + */ + WRITE_ONCE(nohz.has_blocked, 0); + for_each_cpu(balance_cpu, nohz.idle_cpus_mask) { if (balance_cpu == this_cpu || !idle_cpu(balance_cpu)) continue; @@ -9383,11 +9426,16 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) * work being done for other cpus. Next load * balancing owner will pick it up. */ - if (need_resched()) - break; + if (need_resched()) { + has_blocked_load = true; + goto abort; + } rq = cpu_rq(balance_cpu); + update_blocked_averages(rq->cpu); + has_blocked_load |= rq->has_blocked_load; + /* * If time for next balance is due, * do the balance. @@ -9400,7 +9448,6 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) cpu_load_update_idle(rq); rq_unlock_irq(rq, &rf); - update_blocked_averages(rq->cpu); if (flags & NOHZ_BALANCE_KICK) rebalance_domains(rq, CPU_IDLE); } @@ -9415,7 +9462,13 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) if (flags & NOHZ_BALANCE_KICK) rebalance_domains(this_rq, CPU_IDLE); - nohz.next_stats = next_stats; + WRITE_ONCE(nohz.next_blocked, + now + msecs_to_jiffies(LOAD_AVG_PERIOD)); + +abort: + /* There is still blocked load, enable periodic update */ + if (has_blocked_load) + WRITE_ONCE(nohz.has_blocked, 1); /* * next_balance will be updated only when there is a need. @@ -10046,6 +10099,7 @@ __init void init_sched_fair_class(void) #ifdef CONFIG_NO_HZ_COMMON nohz.next_balance = jiffies; + nohz.next_blocked = jiffies; zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); #endif #endif /* SMP */ diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index e200045..ad9b929 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -723,6 +723,7 @@ struct rq { #ifdef CONFIG_SMP unsigned long last_load_update_tick; unsigned long last_blocked_load_update_tick; + unsigned int has_blocked_load; #endif /* CONFIG_SMP */ unsigned int nohz_tick_stopped; atomic_t nohz_flags; From patchwork Tue Feb 6 19:23:06 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Guittot X-Patchwork-Id: 127081 Delivered-To: patch@linaro.org Received: by 10.46.124.24 with SMTP id x24csp3208729ljc; Tue, 6 Feb 2018 11:24:03 -0800 (PST) X-Google-Smtp-Source: AH8x224/UX8oMrYas1nBcYZyCDSEnchvQ0lhWm0A7/+fnO8H8OHblo4op77Ge+tVFS2U1gBz1mdO X-Received: by 10.98.31.70 with SMTP id f67mr3441263pff.196.1517945043071; Tue, 06 Feb 2018 11:24:03 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1517945043; cv=none; d=google.com; s=arc-20160816; b=DK6LgfUmTG/zh93bJ5/Yx0ELSCdjpm21ni+veaLSIiIE5uNBGPXiPLSjElG91H34d7 6538MxhOHzOCWTM+ka2Xz0dDF1IxbI7WqwQJnfFHbpQS9nVC1mKM+FTb2NsKGGhf0MGL X/Twil2uJV8TsPMQKRWboTIZKuj45GL3G+Dy+MeOwmmCDhTLFUTd/NcDLWNeF8ql/y/n wKpN1997auVszkBH38fAHmgjaH21rLWi1d+rjDgN5u8rG0pljTstvs3J3n5yrcfNB6vN Ats5li0qlMkyJ02/Ktvbg2Tk674rLpAk2yFfZPljZSd3Si+v1UvciaFnr45iA+OIiau3 eDTA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=fc4hgkQE9XHngMAbtECDPNkh8BUWa9POuhBW2Vv1f1Y=; b=yQa0d/APjuiGH6Vjz+4h5VRHLZCgw1dsjpCbgt4LvzufAHtT8mTbvkBBO5UXfVMO82 Mb1miME2phK7L4aeewbxAbeOAPqeB5zqywU8QttIjJOf6z5/k8yTa9RfSTlBfPry1JPH uC14xRgSnFHmtKTNAGGwXzz7U2k7cfkRKWRHmwDgJgtvoJtzecy0Jzyu6ucP5GTD306t aKwBX1+DZ+pcp29K+MJ+KWBe0rCQG0xwXmxO5IdiCWaKpgeVapBFMeflIosoP/lnB6c8 Ri4obmZtY53Ex/oILjRQ/jYd+f0VTFseT+UPMe1P/t0nipefYpK3TnGFHHWda4Ofqt8D WaHQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=bwl9mKLg; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id y3si447208pgo.193.2018.02.06.11.24.02; Tue, 06 Feb 2018 11:24:03 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=bwl9mKLg; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753055AbeBFTXZ (ORCPT + 18 others); Tue, 6 Feb 2018 14:23:25 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:37764 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752884AbeBFTXW (ORCPT ); Tue, 6 Feb 2018 14:23:22 -0500 Received: by mail-wm0-f66.google.com with SMTP id v71so6049745wmv.2 for ; Tue, 06 Feb 2018 11:23:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=fc4hgkQE9XHngMAbtECDPNkh8BUWa9POuhBW2Vv1f1Y=; b=bwl9mKLgEJbVPhA9eNvFJGyHkM3TQGO2zz+YTvjZa6CPFXZ8qCHoOkNGt8NKJ9846m eCDE+aUTmTiUzUGOahHBNyhy6Q0ja1hiLjtSU4nIj+JY/LZFHcSBTU13w4saLSKZBKGi haO3HT22JPD0Bukw3ROS9gOwE/GhBgd28etBw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=fc4hgkQE9XHngMAbtECDPNkh8BUWa9POuhBW2Vv1f1Y=; b=isZewW95psykZnX9ClHQC/d92dZ2DzA2183Lv9Z+1Y9h4bNNnIvzjTN/ioc5SWLJWJ GiDdldIdmUQEYotMHLAE3D4DvbP/N/GmwZFPC99zdqMdWdLSbxO/a+/2tIN6Y03PMHhY Vt+LO2cm01a7KW581PcaYy0syeW9X4AzoyRS0VwDEzEjugjM1VSudikiwIeyssdhrmdk 2w4OYXAGQk2QcnreOkB693VjYTdEVG/jFDa9KSvmdgS67lMNC6EpJgfQl6Z3e4sbb2sW faEADMp9yuyB/ScBj4eUs9jUF5xEd+Yn5RTdevvTGLA00WCwefzvQLH9dzCzJ2p/Elj6 919Q== X-Gm-Message-State: APf1xPCJ2l0ltWfQlybqIFSBO10Owzoo+sz3mKgE61buosfIPZ/FBuPN 8jVfXpTROdLJGvvXhtPQe19+Ww== X-Received: by 10.80.220.141 with SMTP id r13mr5059023edk.120.1517945001089; Tue, 06 Feb 2018 11:23:21 -0800 (PST) Received: from localhost.localdomain ([2a01:e0a:f:6020:29bb:43dd:7d11:e095]) by smtp.gmail.com with ESMTPSA id s5sm78155eda.60.2018.02.06.11.23.19 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 06 Feb 2018 11:23:20 -0800 (PST) From: Vincent Guittot To: peterz@infradead.org, mingo@kernel.org, linux-kernel@vger.kernel.org, valentin.schneider@arm.com Cc: morten.rasmussen@foss.arm.com, brendan.jackman@arm.com, dietmar.eggemann@arm.com, Vincent Guittot Subject: [PATCH v2 2/3] sched: reduce the periodic update duration Date: Tue, 6 Feb 2018 20:23:06 +0100 Message-Id: <1517944987-343-3-git-send-email-vincent.guittot@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1517944987-343-1-git-send-email-vincent.guittot@linaro.org> References: <1517944987-343-1-git-send-email-vincent.guittot@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Instead of using the cfs_rq_is_decayed() which monitors all *_avg and *_sum, we create a cfs_rq_has_blocked() which only takes care of util_avg and load_avg. We are only interested by these 2 values which are decaying faster than the *_sum so we can stop the periodic update earlier. Signed-off-by: Vincent Guittot --- kernel/sched/fair.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) -- 2.7.4 diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b9660b5..e203297 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7337,6 +7337,19 @@ static void attach_tasks(struct lb_env *env) rq_unlock(env->dst_rq, &rf); } +static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq) +{ + if (cfs_rq->avg.load_avg) + return true; + + if (cfs_rq->avg.util_avg) + return true; + + return false; +} + +#ifdef CONFIG_FAIR_GROUP_SCHED + static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq) { if (cfs_rq->load.weight) @@ -7354,8 +7367,6 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq) return true; } -#ifdef CONFIG_FAIR_GROUP_SCHED - static void update_blocked_averages(int cpu) { struct rq *rq = cpu_rq(cpu); @@ -7391,7 +7402,9 @@ static void update_blocked_averages(int cpu) */ if (cfs_rq_is_decayed(cfs_rq)) list_del_leaf_cfs_rq(cfs_rq); - else + + /* Don't need periodic decay once load/util_avg are null */ + if (cfs_rq_has_blocked(cfs_rq)) done = false; } @@ -7461,7 +7474,7 @@ static inline void update_blocked_averages(int cpu) update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq); #ifdef CONFIG_NO_HZ_COMMON rq->last_blocked_load_update_tick = jiffies; - if (cfs_rq_is_decayed(cfs_rq)) + if (!cfs_rq_has_blocked(cfs_rq)) rq->has_blocked_load = 0; #endif rq_unlock_irqrestore(rq, &rf); From patchwork Tue Feb 6 19:23:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Guittot X-Patchwork-Id: 127080 Delivered-To: patch@linaro.org Received: by 10.46.124.24 with SMTP id x24csp3208466ljc; Tue, 6 Feb 2018 11:23:31 -0800 (PST) X-Google-Smtp-Source: AH8x227eq9kQfhaxntP7tcbhfG7egMMgzTprWbfWY3E/shQ0bsga38HZUHODCu/PZ7kWwzGIJEY0 X-Received: by 2002:a17:902:1746:: with SMTP id i64-v6mr3359474pli.53.1517945011594; Tue, 06 Feb 2018 11:23:31 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1517945011; cv=none; d=google.com; s=arc-20160816; b=v80qcgvVvxD8Lo3ZzaZBpkQHEYjz24U/6kvqdk/TcRD276T0nq44NMITD8c41vgpiS ey3kdmNxeVpfpI+9RNR+GeMHmF2BWSYhYVSc/4nvsji19TvnOtnQ9+HLC6R+ZvEnwFeR cojmPPu1QUFietbgtEsy93G/AjNLE2E92R9eWOqumWnu0kKMlqzG4XP/ZUif3CC7Cy2H SXN5cgpAdsPZ5ffOagq9XCDszUqspKlcGHlhoFLwD4JYxy5JqlfyQCOABaZRo/nFElma fVcrXyb8JtLN79prxZEIhFoLPEWGU1JHMEDKDcyXkMVEB/PhiONvaOm0zU+LIGuBUwUV 1WKA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=tT7Qk2gRgh/hDQ3lYMdUYy4kTKgrgAd2GsvFw/+KYZg=; b=cTCxJYbaVUmUSm54CcsexinnreCgTNkfUc+gB8cIzzOfwQAXGuaehKmCGhgDG6c3+A giGxU1fd1GL8NlCFOsaRacyPYfmCNAILWPpw8a82t1anXsD/mhepQf4OoLIkMRVH4ySd pFdVRgh4BktLeYyP9931yPn3TVnRA0bA6cIBq4NIQ1y80tGWIHZcgktLXvuz/acGDZ2D wPCOD65mIoj3F4Y/6QO632rCK6HCJA7gPWTo9blZq/AGvzKEI6eVSwV7MGspQ6Fu6HwW IjuMOk5titHJEPf+G3F2XoM4Q3VyZAfOc3g6UGDFogQMyMxgbhKba7pxLCm3bOm74lU7 KwFA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=A34b3Pok; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id k12si900171pgs.499.2018.02.06.11.23.31; Tue, 06 Feb 2018 11:23:31 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=A34b3Pok; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753277AbeBFTX3 (ORCPT + 18 others); Tue, 6 Feb 2018 14:23:29 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:56049 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752922AbeBFTXY (ORCPT ); Tue, 6 Feb 2018 14:23:24 -0500 Received: by mail-wm0-f66.google.com with SMTP id 143so5831104wma.5 for ; Tue, 06 Feb 2018 11:23:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=tT7Qk2gRgh/hDQ3lYMdUYy4kTKgrgAd2GsvFw/+KYZg=; b=A34b3PokbLoY4fUwmypNsBV1uimEXVoqvQ6LFW5ejabMNhjXDb3IKZERwyTzPpSvm6 3Gnhc3D/B/1t+fdgCI+VNXQiqMoptmVz0MfBLS6PSltEQSYqIMRZw6UiGF2H9Z8eLQbx b8jLzlkHZLPcWo5Gv0bOjNwBvwPA8MAVdNCbs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=tT7Qk2gRgh/hDQ3lYMdUYy4kTKgrgAd2GsvFw/+KYZg=; b=kMS+MadHXxT/l7300T7Mwf3vqJwlPH/xmSxCBME0unNiTIxvg92aVdx0NK3lys/FHb VALxtbL8AyOn2fazn5VGekB8pzkYE09v85LldKZPHR93NbGTg2txxN36C9ATjzdH5OMb 2tzc9/rCD/3qV6STwi8AiYJQG01KZSR0zUOSmphTbDwuydS7uv8T5j3qnDeL61m4fqxJ 9iC8Txy0QpyvrFbbZgFpnw+HP7xm+ZkeGQGlQ4djG1YqDRz6AMblpcBLhAHUOwaQkgHa pWmPB5YZF3T39W1LuNHaSetoaQ/vx4ra1XfyIhh4HO8MW7CFdLkdJZQGWZ7gpSG0R2xa zncQ== X-Gm-Message-State: APf1xPDvyPta7xnrcRyvjUfgGzMBEi6AridFkO3OlxsF1I8rczcnGEnF r51Y8/0NWXWw19VWe3D2Z4HTmA== X-Received: by 10.80.224.195 with SMTP id j3mr5066887edl.50.1517945002655; Tue, 06 Feb 2018 11:23:22 -0800 (PST) Received: from localhost.localdomain ([2a01:e0a:f:6020:29bb:43dd:7d11:e095]) by smtp.gmail.com with ESMTPSA id s5sm78155eda.60.2018.02.06.11.23.21 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 06 Feb 2018 11:23:21 -0800 (PST) From: Vincent Guittot To: peterz@infradead.org, mingo@kernel.org, linux-kernel@vger.kernel.org, valentin.schneider@arm.com Cc: morten.rasmussen@foss.arm.com, brendan.jackman@arm.com, dietmar.eggemann@arm.com, Vincent Guittot Subject: [PATCH v2 3/3] sched: update blocked load when newly idle Date: Tue, 6 Feb 2018 20:23:07 +0100 Message-Id: <1517944987-343-4-git-send-email-vincent.guittot@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1517944987-343-1-git-send-email-vincent.guittot@linaro.org> References: <1517944987-343-1-git-send-email-vincent.guittot@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When NEWLY_IDLE load balance is not triggered, we might need to update the blocked load anyway. We can kick an ilb so an idle CPU will take care of updating blocked load or we can try to update them locally before entering idle. In the latter case, we reuse part of the nohz_idle_balance. Signed-off-by: Vincent Guittot --- kernel/sched/fair.c | 102 ++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 84 insertions(+), 18 deletions(-) -- 2.7.4 diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e203297..dcac728 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8829,6 +8829,9 @@ update_next_balance(struct sched_domain *sd, unsigned long *next_balance) *next_balance = next; } +static bool _nohz_idle_balance(struct rq *this_rq, unsigned int flags, enum cpu_idle_type idle); +static void kick_ilb(unsigned int flags); + /* * idle_balance is called by schedule() if this_cpu is about to become * idle. Attempts to pull tasks from other CPUs. @@ -8863,12 +8866,26 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) if (this_rq->avg_idle < sysctl_sched_migration_cost || !this_rq->rd->overload) { + unsigned long has_blocked = READ_ONCE(nohz.has_blocked); + unsigned long next_blocked = READ_ONCE(nohz.next_blocked); + rcu_read_lock(); sd = rcu_dereference_check_sched_domain(this_rq->sd); if (sd) update_next_balance(sd, &next_balance); rcu_read_unlock(); + /* + * Update blocked idle load if it has not been done for a + * while. Try to do it locally before entering idle but kick a + * ilb if it takes too much time and/or might delay next local + * wake up + */ + if (has_blocked && time_after_eq(jiffies, next_blocked) && + (this_rq->avg_idle < sysctl_sched_migration_cost || + !_nohz_idle_balance(this_rq, NOHZ_STATS_KICK, CPU_NEWLY_IDLE))) + kick_ilb(NOHZ_STATS_KICK); + goto out; } @@ -9393,30 +9410,24 @@ static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) #ifdef CONFIG_NO_HZ_COMMON /* - * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the - * rebalancing for all the cpus for whom scheduler ticks are stopped. + * Internal function that runs load balance for all idle cpus. The load balance + * can be a simple update of blocked load or a complete load balance with + * tasks movement depending of flags. + * For newly idle mode, we abort the loop if it takes too much time and return + * false to notify that the loop has not be completed and a ilb should be kick. */ -static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) +static bool _nohz_idle_balance(struct rq *this_rq, unsigned int flags, enum cpu_idle_type idle) { /* Earliest time when we have to do rebalance again */ unsigned long now = jiffies; unsigned long next_balance = now + 60*HZ; - unsigned long next_stats = now + msecs_to_jiffies(LOAD_AVG_PERIOD); + bool has_blocked_load = false; int update_next_balance = 0; int this_cpu = this_rq->cpu; - unsigned int flags; int balance_cpu; + int ret = false; struct rq *rq; - - if (!(atomic_read(nohz_flags(this_cpu)) & NOHZ_KICK_MASK)) - return false; - - if (idle != CPU_IDLE) { - atomic_andnot(NOHZ_KICK_MASK, nohz_flags(this_cpu)); - return false; - } - - flags = atomic_fetch_andnot(NOHZ_KICK_MASK, nohz_flags(this_cpu)); + u64 curr_cost = 0; SCHED_WARN_ON((flags & NOHZ_KICK_MASK) == NOHZ_BALANCE_KICK); @@ -9431,6 +9442,10 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) WRITE_ONCE(nohz.has_blocked, 0); for_each_cpu(balance_cpu, nohz.idle_cpus_mask) { + u64 t0, domain_cost; + + t0 = sched_clock_cpu(this_cpu); + if (balance_cpu == this_cpu || !idle_cpu(balance_cpu)) continue; @@ -9444,6 +9459,16 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) goto abort; } + /* + * If the update is done while CPU becomes idle, we abort + * the update when its cost is higher than the average idle + * time in orde to not delay a possible wake up. + */ + if (idle == CPU_NEWLY_IDLE && this_rq->avg_idle < curr_cost) { + has_blocked_load = true; + goto abort; + } + rq = cpu_rq(balance_cpu); update_blocked_averages(rq->cpu); @@ -9456,10 +9481,10 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) if (time_after_eq(jiffies, rq->next_balance)) { struct rq_flags rf; - rq_lock_irq(rq, &rf); + rq_lock_irqsave(rq, &rf); update_rq_clock(rq); cpu_load_update_idle(rq); - rq_unlock_irq(rq, &rf); + rq_unlock_irqrestore(rq, &rf); if (flags & NOHZ_BALANCE_KICK) rebalance_domains(rq, CPU_IDLE); @@ -9469,15 +9494,27 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) next_balance = rq->next_balance; update_next_balance = 1; } + + domain_cost = sched_clock_cpu(this_cpu) - t0; + curr_cost += domain_cost; + + } + + /* Newly idle CPU doesn't need an update */ + if (idle != CPU_NEWLY_IDLE) { + update_blocked_averages(this_cpu); + has_blocked_load |= this_rq->has_blocked_load; } - update_blocked_averages(this_cpu); if (flags & NOHZ_BALANCE_KICK) rebalance_domains(this_rq, CPU_IDLE); WRITE_ONCE(nohz.next_blocked, now + msecs_to_jiffies(LOAD_AVG_PERIOD)); + /* The full idle balance loop has been done */ + ret = true; + abort: /* There is still blocked load, enable periodic update */ if (has_blocked_load) @@ -9491,6 +9528,35 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) if (likely(update_next_balance)) nohz.next_balance = next_balance; + return ret; +} + +/* + * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the + * rebalancing for all the cpus for whom scheduler ticks are stopped. + */ +static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) +{ + int this_cpu = this_rq->cpu; + unsigned int flags; + + if (!(atomic_read(nohz_flags(this_cpu)) & NOHZ_KICK_MASK)) + return false; + + if (idle != CPU_IDLE) { + atomic_andnot(NOHZ_KICK_MASK, nohz_flags(this_cpu)); + return false; + } + + /* + * barrier, pairs with nohz_balance_enter_idle(), ensures ... + */ + flags = atomic_fetch_andnot(NOHZ_KICK_MASK, nohz_flags(this_cpu)); + if (!(flags & NOHZ_KICK_MASK)) + return false; + + _nohz_idle_balance(this_rq, flags, idle); + return true; } #else