分类 Performance 下的文章

EDK2 Fastboot Flash分析

这段时间都在忙着port custom features from LK to edk2,搭了个框后主要耗时在custom dfastboot download。一般我们在fastboot flash xxx_part xxx_part.img时,会先触发一个download cmd完成后再触发一个flash cmd。我们先看下QCOM原生CmdDownload()。/*...阅读全文

EDK2 Overview

最近在移BL到UEFI, 来大概看下基础。UEFI(Unified Extensible Firmware Interface)是Intel提出的一种规范(specification),由PC BIOS而来,如下图(阿桑的wikipedia打不开?画个txt pic),介于OS和FW之间,QCOM Android BL似乎用它来代替LK。UEFI is based on ...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