Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754740Ab3GOUDq (ORCPT ); Mon, 15 Jul 2013 16:03:46 -0400 Received: from merlin.infradead.org ([205.233.59.134]:48372 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753403Ab3GOUDp (ORCPT ); Mon, 15 Jul 2013 16:03:45 -0400 Date: Mon, 15 Jul 2013 22:03:21 +0200 From: Peter Zijlstra To: Mel Gorman Cc: Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML Subject: Re: [PATCH 16/18] sched: Avoid overloading CPUs on a preferred NUMA node Message-ID: <20130715200321.GN17211@twins.programming.kicks-ass.net> References: <1373901620-2021-1-git-send-email-mgorman@suse.de> <1373901620-2021-17-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1373901620-2021-17-git-send-email-mgorman@suse.de> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3516 Lines: 109 On Mon, Jul 15, 2013 at 04:20:18PM +0100, Mel Gorman wrote: > --- > kernel/sched/fair.c | 105 +++++++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 83 insertions(+), 22 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 3f0519c..8ee1c8e 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -846,29 +846,92 @@ static inline int task_faults_idx(int nid, int priv) > return 2 * nid + priv; > } > > -static unsigned long weighted_cpuload(const int cpu); > +static unsigned long source_load(int cpu, int type); > +static unsigned long target_load(int cpu, int type); > +static unsigned long power_of(int cpu); > +static long effective_load(struct task_group *tg, int cpu, long wl, long wg); > + > +static int task_numa_find_cpu(struct task_struct *p, int nid) > +{ > + int node_cpu = cpumask_first(cpumask_of_node(nid)); > + int cpu, src_cpu = task_cpu(p), dst_cpu = src_cpu; > + unsigned long src_load, dst_load; > + unsigned long min_load = ULONG_MAX; > + struct task_group *tg = task_group(p); > + s64 src_eff_load, dst_eff_load; > + struct sched_domain *sd; > + unsigned long weight; > + bool balanced; > + int imbalance_pct, idx = -1; > > + /* No harm being optimistic */ > + if (idle_cpu(node_cpu)) > + return node_cpu; > > + /* > + * Find the lowest common scheduling domain covering the nodes of both > + * the CPU the task is currently running on and the target NUMA node. > + */ > + rcu_read_lock(); > + for_each_domain(src_cpu, sd) { > + if (cpumask_test_cpu(node_cpu, sched_domain_span(sd))) { > + /* > + * busy_idx is used for the load decision as it is the > + * same index used by the regular load balancer for an > + * active cpu. > + */ > + idx = sd->busy_idx; > + imbalance_pct = sd->imbalance_pct; > + break; > + } > + } > + rcu_read_unlock(); > > + if (WARN_ON_ONCE(idx == -1)) > + return src_cpu; > > + /* > + * XXX the below is mostly nicked from wake_affine(); we should > + * see about sharing a bit if at all possible; also it might want > + * some per entity weight love. > + */ > + weight = p->se.load.weight; > > + src_load = source_load(src_cpu, idx); > + > + src_eff_load = 100 + (imbalance_pct - 100) / 2; > + src_eff_load *= power_of(src_cpu); > + src_eff_load *= src_load + effective_load(tg, src_cpu, -weight, -weight); So did you try with this effective_load() term 'missing'? > + > + for_each_cpu(cpu, cpumask_of_node(nid)) { > + dst_load = target_load(cpu, idx); > + > + /* If the CPU is idle, use it */ > + if (!dst_load) > + return dst_cpu; > + > + /* Otherwise check the target CPU load */ > + dst_eff_load = 100; > + dst_eff_load *= power_of(cpu); > + dst_eff_load *= dst_load + effective_load(tg, cpu, weight, weight); > + > + /* > + * Destination is considered balanced if the destination CPU is > + * less loaded than the source CPU. Unfortunately there is a > + * risk that a task running on a lightly loaded CPU will not > + * migrate to its preferred node due to load imbalances. > + */ > + balanced = (dst_eff_load <= src_eff_load); > + if (!balanced) > + continue; > + > + if (dst_load < min_load) { > + min_load = dst_load; > + dst_cpu = cpu; > } > } > > + return dst_cpu; > } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/