分类 Performance 下的文章

schedutil CPUFreq governor 代码分析

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参考内核5.x, code是kernel/sched/cpufreq_schedutil.c，配置说明：config CPU_FREQ_GOV_SCHEDUTIL bool "'schedutil' cpufreq policy governor" depends on CPU_FREQ && SMP select CP...阅读全文

ARM EAS Overview

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EAS全称是Energy Aware Scheduling，主要目标就是降低功耗同时兼顾性能，专门针对异构CPU，比如Arm大小核架构。EAS利用task load(PELT or WALT) 和 Engery Model (EM) 找到engergy-efficient CPU。这里的PELT是per-entity load tracking，上游Linux使用。QCO...阅读全文

CPUFreq policy代码分析

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参考4.9，主要了解几个结构成员：struct cpufreq_policy { /* CPUs sharing clock, require sw coordination */ cpumask_var_t cpus; /* Online CPUs only */ cpumask_var_t related_cp...阅读全文

CPUFreq boost代码分析

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参考4.9内核，还是先看文档描述：IntroductionSome CPUs support a functionality to raise the operating frequency ofsome cores in a multi-core package if certain conditions apply, mostlyif the whole chip i...阅读全文

Linux CPUFreq Subsystem Overview

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参考4.9，CPUFreq即CPU Frequency scaling或者CPU performance scaling，允许你运行时改变CPU clock speed.文档路径: ./Documentation/cpu-freq/，先来看几个概念：Some CPU frequency scaling-capable processor switch between va...阅读全文

分析ueventd Coldboot耗时问题

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安卓go平台启动时间发现如下ueventd耗时1.907s问题：01-11 00:20:02.854 0 0 I init : Parsing file /odm/etc/init... 01-11 00:20:02.854 0 0 E init : Unable to open '/odm/etc/init': No such...阅读全文
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