分类 Performance 下的文章

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

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

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