From patchwork Mon May 23 10:58:51 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Morten Rasmussen X-Patchwork-Id: 68359 Delivered-To: patch@linaro.org Received: by 10.140.92.199 with SMTP id b65csp13402qge; Mon, 23 May 2016 03:58:56 -0700 (PDT) X-Received: by 10.98.10.25 with SMTP id s25mr1182908pfi.124.1464001130652; Mon, 23 May 2016 03:58:50 -0700 (PDT) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id d15si51081055pfb.137.2016.05.23.03.58.49; Mon, 23 May 2016 03:58:50 -0700 (PDT) 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; 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 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754442AbcEWK6n (ORCPT + 30 others); Mon, 23 May 2016 06:58:43 -0400 Received: from foss.arm.com ([217.140.101.70]:50163 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754395AbcEWK6j (ORCPT ); Mon, 23 May 2016 06:58:39 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2C2C7456; Mon, 23 May 2016 03:59:01 -0700 (PDT) Received: from e105550-lin.cambridge.arm.com (e105550-lin.cambridge.arm.com [10.1.207.130]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D41FD3F246; Mon, 23 May 2016 03:58:37 -0700 (PDT) From: Morten Rasmussen To: peterz@infradead.org, mingo@redhat.com Cc: dietmar.eggemann@arm.com, yuyang.du@intel.com, vincent.guittot@linaro.org, mgalbraith@suse.de, linux-kernel@vger.kernel.org, Morten Rasmussen Subject: [PATCH 09/16] sched/fair: Let asymmetric cpu configurations balance at wake-up Date: Mon, 23 May 2016 11:58:51 +0100 Message-Id: <1464001138-25063-10-git-send-email-morten.rasmussen@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1464001138-25063-1-git-send-email-morten.rasmussen@arm.com> References: <1464001138-25063-1-git-send-email-morten.rasmussen@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, SD_WAKE_AFFINE always takes priority over wakeup balancing if SD_BALANCE_WAKE is set on the sched_domains. For asymmetric configurations SD_WAKE_AFFINE is only desirable if the waking task's compute demand (utilization) is suitable for the cpu capacities available within the SD_WAKE_AFFINE sched_domain. If not, let wakeup balancing take over (find_idlest_{group, cpu}()). The assumption is that SD_WAKE_AFFINE is never set for a sched_domain containing cpus with different capacities. This is enforced by a previous patch based on the SD_ASYM_CPUCAPACITY flag. Ideally, we shouldn't set 'want_affine' in the first place, but we don't know if SD_BALANCE_WAKE is enabled on the sched_domain(s) until we start traversing them. cc: Ingo Molnar cc: Peter Zijlstra Signed-off-by: Morten Rasmussen --- kernel/sched/fair.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) -- 1.9.1 diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 564215d..ce44fa7 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -114,6 +114,12 @@ unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; #endif +/* + * The margin used when comparing utilization with cpu capacity: + * util * 1024 < capacity * margin + */ +unsigned int capacity_margin = 1280; /* ~20% */ + static inline void update_load_add(struct load_weight *lw, unsigned long inc) { lw->weight += inc; @@ -5293,6 +5299,25 @@ static int cpu_util(int cpu) return (util >= capacity) ? capacity : util; } +static inline int task_util(struct task_struct *p) +{ + return p->se.avg.util_avg; +} + +static int wake_cap(struct task_struct *p, int cpu, int prev_cpu) +{ + long delta; + long prev_cap = capacity_of(prev_cpu); + + delta = cpu_rq(cpu)->rd->max_cpu_capacity - prev_cap; + + /* prev_cpu is fairly close to max, no need to abort wake_affine */ + if (delta < prev_cap >> 3) + return 0; + + return prev_cap * 1024 < task_util(p) * capacity_margin; +} + /* * select_task_rq_fair: Select target runqueue for the waking task in domains * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE, @@ -5316,7 +5341,8 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f if (sd_flag & SD_BALANCE_WAKE) { record_wakee(p); - want_affine = !wake_wide(p) && cpumask_test_cpu(cpu, tsk_cpus_allowed(p)); + want_affine = !wake_wide(p) && !wake_cap(p, cpu, prev_cpu) + && cpumask_test_cpu(cpu, tsk_cpus_allowed(p)); } rcu_read_lock();