2024-10-10发表linux / 性能优化7 分钟读完 (大约1098个字)

安装依赖

确保已安装 perf 和 FlameGraph 工具。

FlameGraph 通过以下命令下载

git clone https://github.com/brendangregg/FlameGraph.git

原理

2024-10-10发表linux / 性能优化16 分钟读完 (大约2455个字)

性能优化工具-perf

概述

perf 是一个强大的 Linux 性能分析工具，它可以用来收集和分析性能数据。

perf的命令有很多，下文将就其中常用的几条进行阐述


usage: perf [--version] [--help] [OPTIONS] COMMAND [ARGS]

The most commonly used perf commands are:
  annotate        Read perf.data (created by perf record) and display annotated code
  archive         Create archive with object files with build-ids found in perf.data file
  bench           General framework for benchmark suites
  buildid-cache   Manage build-id cache.
  buildid-list    List the buildids in a perf.data file
  c2c             Shared Data C2C/HITM Analyzer.
  config          Get and set variables in a configuration file.
  daemon          Run record sessions on background
  data            Data file related processing
  diff            Read perf.data files and display the differential profile
  evlist          List the event names in a perf.data file
  ftrace          simple wrapper for kernel's ftrace functionality
  inject          Filter to augment the events stream with additional information
  iostat          Show I/O performance metrics
  kallsyms        Searches running kernel for symbols
  kvm             Tool to trace/measure kvm guest os
  list            List all symbolic event types
  mem             Profile memory accesses
  record          Run a command and record its profile into perf.data
  report          Read perf.data (created by perf record) and display the profile
  script          Read perf.data (created by perf record) and display trace output
  stat            Run a command and gather performance counter statistics
  test            Runs sanity tests.
  top             System profiling tool.
  version         display the version of perf binary
  probe           Define new dynamic tracepoints
  trace           strace inspired tool
  kmem            Tool to trace/measure kernel memory properties
  kwork           Tool to trace/measure kernel work properties (latencies)
  lock            Analyze lock events
  sched           Tool to trace/measure scheduler properties (latencies)
  timechart       Tool to visualize total system behavior during a workload

See 'perf help COMMAND' for more information on a specific command.

安装

2024-09-18发表linux / linux内核8 分钟读完 (大约1240个字)

linux二进制文件加载源码分析

linux二进制加载

结构

linux_binfmt 用来定义二进制格式的结构，代表某种特定的格式，比如elf

struct linux_binfmt {
	struct list_head lh; // 链表头部
	struct module *module; // 模块
	int (*load_binary)(struct linux_binprm *); // 加载函数
	int (*load_shlib)(struct file *);
#ifdef CONFIG_COREDUMP
	int (*core_dump)(struct coredump_params *cprm); // coredump处理函数，如elf会有定义
	unsigned long min_coredump;	/* minimal dump size */
#endif
} __randomize_layout;

linux_binprm 用来存放可执行文件的各种参数，代表可执行文件的运行时结构

2024-09-15发表golang / 基准测试7 分钟读完 (大约997个字)

golang上下文切换测试

引入

golang是一门高性能的编程语言，基于其轻量，高效的的Goroutine的设计，可以实现很小的协程切换开销。
本文将解释一下基本的协程相关的原理，并实际做一个小的测试，去得到其实际的切换开销

原理

协程

协程（Coroutine）是一种更轻量级的并发编程方式，他是在用户态实现的，相比于线程进程更加轻量，拥有更小的上下文切换开销，栈空间等等。
协程主要分为两种类型：

2024-09-04发表c/c++ / 语言特性18 分钟读完 (大约2660个字)

Enum Class Improvements for C++17, C++20 and C++23（C++17、C++20 和 C++23 的枚举类改进）

The evolution of the C++ language continues to bring powerful features that enhance code safety, readability, and maintainability. Among these improvements, we got changes and additions to enum class functionalities across C++17, C++20, and C++23. In this blog post, we’ll explore these advancements, focusing on initialization improvements in C++17, the introduction of the using enum keyword in C++20, and the std::to_underlying utility in C++23.

文章转载自: https://www.cppstories.com/2024/enum-improvements/

alt text
C++ 语言的演变继续带来强大的功能，可增强代码安全性、可读性和可维护性。在这些改进中，我们对 C++17、C++20 和 C++23 中的枚举类功能进行了更改和添加。在这篇博文中，我们将探讨这些改进，重点介绍 C++17 中的初始化改进、C++20 中 using enum 关键字的引入以及 C++23 中的 std：：to_underlying 实用程序。