From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933974AbbELTit (ORCPT ); Tue, 12 May 2015 15:38:49 -0400 Received: from foss.arm.com ([217.140.101.70]:33947 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933853AbbELTin (ORCPT ); Tue, 12 May 2015 15:38:43 -0400 From: Morten Rasmussen To: peterz@infradead.org, mingo@redhat.com Cc: vincent.guittot@linaro.org, Dietmar Eggemann , yuyang.du@intel.com, preeti@linux.vnet.ibm.com, mturquette@linaro.org, rjw@rjwysocki.net, Juri Lelli , sgurrappadi@nvidia.com, pang.xunlei@zte.com.cn, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, morten.rasmussen@arm.com Subject: [RFCv4 PATCH 22/34] sched: Calculate energy consumption of sched_group Date: Tue, 12 May 2015 20:38:57 +0100 Message-Id: <1431459549-18343-23-git-send-email-morten.rasmussen@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1431459549-18343-1-git-send-email-morten.rasmussen@arm.com> References: <1431459549-18343-1-git-send-email-morten.rasmussen@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For energy-aware load-balancing decisions it is necessary to know the energy consumption estimates of groups of cpus. This patch introduces a basic function, sched_group_energy(), which estimates the energy consumption of the cpus in the group and any resources shared by the members of the group. NOTE: The function has five levels of identation and breaks the 80 character limit. Refactoring is necessary. cc: Ingo Molnar cc: Peter Zijlstra Signed-off-by: Morten Rasmussen --- kernel/sched/fair.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 146 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 70f2700..2677ca6 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4831,6 +4831,152 @@ static inline bool energy_aware(void) return sched_feat(ENERGY_AWARE); } +/* + * cpu_norm_usage() returns the cpu usage relative to a specific capacity, + * i.e. it's busy ratio, in the range [0..SCHED_LOAD_SCALE] which is useful for + * energy calculations. Using the scale-invariant usage returned by + * get_cpu_usage() and approximating scale-invariant usage by: + * + * usage ~ (curr_freq/max_freq)*1024 * capacity_orig/1024 * running_time/time + * + * the normalized usage can be found using the specific capacity. + * + * capacity = capacity_orig * curr_freq/max_freq + * + * norm_usage = running_time/time ~ usage/capacity + */ +static unsigned long cpu_norm_usage(int cpu, unsigned long capacity) +{ + int usage = __get_cpu_usage(cpu); + + if (usage >= capacity) + return SCHED_CAPACITY_SCALE; + + return (usage << SCHED_CAPACITY_SHIFT)/capacity; +} + +static unsigned long group_max_usage(struct sched_group *sg) +{ + int i; + unsigned long max_usage = 0; + + for_each_cpu(i, sched_group_cpus(sg)) + max_usage = max(max_usage, get_cpu_usage(i)); + + return max_usage; +} + +/* + * group_norm_usage() returns the approximated group usage relative to it's + * current capacity (busy ratio) in the range [0..SCHED_LOAD_SCALE] for use in + * energy calculations. Since task executions may or may not overlap in time in + * the group the true normalized usage is between max(cpu_norm_usage(i)) and + * sum(cpu_norm_usage(i)) when iterating over all cpus in the group, i. The + * latter is used as the estimate as it leads to a more pessimistic energy + * estimate (more busy). + */ +static unsigned long group_norm_usage(struct sched_group *sg, int cap_idx) +{ + int i; + unsigned long usage_sum = 0; + unsigned long capacity = sg->sge->cap_states[cap_idx].cap; + + for_each_cpu(i, sched_group_cpus(sg)) + usage_sum += cpu_norm_usage(i, capacity); + + if (usage_sum > SCHED_CAPACITY_SCALE) + return SCHED_CAPACITY_SCALE; + return usage_sum; +} + +static int find_new_capacity(struct sched_group *sg, + struct sched_group_energy *sge) +{ + int idx; + unsigned long util = group_max_usage(sg); + + for (idx = 0; idx < sge->nr_cap_states; idx++) { + if (sge->cap_states[idx].cap >= util) + return idx; + } + + return idx; +} + +/* + * sched_group_energy(): Returns absolute energy consumption of cpus belonging + * to the sched_group including shared resources shared only by members of the + * group. Iterates over all cpus in the hierarchy below the sched_group starting + * from the bottom working it's way up before going to the next cpu until all + * cpus are covered at all levels. The current implementation is likely to + * gather the same usage statistics multiple times. This can probably be done in + * a faster but more complex way. + */ +static unsigned int sched_group_energy(struct sched_group *sg_top) +{ + struct sched_domain *sd; + int cpu, total_energy = 0; + struct cpumask visit_cpus; + struct sched_group *sg; + + WARN_ON(!sg_top->sge); + + cpumask_copy(&visit_cpus, sched_group_cpus(sg_top)); + + while (!cpumask_empty(&visit_cpus)) { + struct sched_group *sg_shared_cap = NULL; + + cpu = cpumask_first(&visit_cpus); + + /* + * Is the group utilization affected by cpus outside this + * sched_group? + */ + sd = highest_flag_domain(cpu, SD_SHARE_CAP_STATES); + if (sd && sd->parent) + sg_shared_cap = sd->parent->groups; + + for_each_domain(cpu, sd) { + sg = sd->groups; + + /* Has this sched_domain already been visited? */ + if (sd->child && group_first_cpu(sg) != cpu) + break; + + do { + struct sched_group *sg_cap_util; + unsigned long group_util; + int sg_busy_energy, sg_idle_energy, cap_idx; + + if (sg_shared_cap && sg_shared_cap->group_weight >= sg->group_weight) + sg_cap_util = sg_shared_cap; + else + sg_cap_util = sg; + + cap_idx = find_new_capacity(sg_cap_util, sg->sge); + group_util = group_norm_usage(sg, cap_idx); + sg_busy_energy = (group_util * sg->sge->cap_states[cap_idx].power) + >> SCHED_CAPACITY_SHIFT; + sg_idle_energy = ((SCHED_LOAD_SCALE-group_util) * sg->sge->idle_states[0].power) + >> SCHED_CAPACITY_SHIFT; + + total_energy += sg_busy_energy + sg_idle_energy; + + if (!sd->child) + cpumask_xor(&visit_cpus, &visit_cpus, sched_group_cpus(sg)); + + if (cpumask_equal(sched_group_cpus(sg), sched_group_cpus(sg_top))) + goto next_cpu; + + } while (sg = sg->next, sg != sd->groups); + } +next_cpu: + continue; + } + + return total_energy; +} + static int wake_wide(struct task_struct *p) { int factor = this_cpu_read(sd_llc_size); -- 1.9.1