如何使 perf sched 支持 workqueue name
问题workqueue name 就是 alloc_workqueue 的第一个参数：/**
* alloc_workqueue - allocate a workqueue
* @fmt: printf format for the name of the workqueue
[...]
#define alloc_workqueue(fmt, flags, max...阅读全文
分类 Performance 下的文章
kworker 调度延迟性能测试和统计
LPC2022 EROFS 提到一个解压调度延迟问题：最近，Android 提了一笔优化 patch for this issue:Author: Sandeep Dhavale <dhavale@google.com>
Date: Thu Dec 22 01:15:29 2022 +0000
EROFS: Replace erofs_unzip...阅读全文
schedutil CPUFreq governor 代码分析
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
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
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
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
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
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