Overview 3 AM. Your alarm goes off. You log into the server and see a single line on the screen: Kernel panic - not syncing: Fatal exception. Then the system reboots. When you finally get back in, the crash scene is completely gone — no logs, no core dump, no call trace. You stare at systemd-logind: System is going down with nothing to work with. If you’ve been in ops for a few years, you’ve been there....
Overview 3 AM, woken up by an alert. You log into the server and find a critical configuration file has been modified, but last shows no one logged in during that window, and bash_history has nothing. You know something happened, but you don’t know who did it or how. This is when you need auditd—the audit system built into the Linux kernel. It’s like an airplane’s black box, recording every critical action on the system: who executed what command, which files were accessed, what configurations were changed, and when privilege escalation occurred....
Overview You’re running a high-frequency trading system online. P99 latency sits at 2ms normally, but occasionally spikes to 20ms. CPU usage isn’t high, memory is sufficient, network is fine. After investigation, you discover the CPU scheduler migrated a critical thread to another core, L3 cache missed entirely, and latency jumped 10x. This kind of problem can’t be solved by adding resources. The issue is “sharing” — all processes share CPU cores, the scheduler distributes freely, and nobody knows which threads are latency-sensitive....
Overview Linux Namespaces and cgroups: The Foundation of Container Technology is an essential skill in SRE operations. In production environments, mastering these techniques can significantly improve system stability and operational efficiency. Why Linux Namespaces and cgroups Matters As systems grow in scale and complexity, traditional operations approaches struggle to meet the demands of modern distributed systems. Linux Namespaces and cgroups helps operations teams: Rapid Problem Resolution: Systematic tools and methods reduce troubleshooting time Improved System Visibility: Establish comprehensive monitoring and observability Proactive Fault Prevention: Identify and fix potential risks before they cause outages Resource Optimization: Allocate and schedule resources efficiently Core Concepts and Principles Basic Concepts The core of Linux Namespaces and cgroups lies in establishing standardized processes and automated toolchains....
Overview Nginx Performance Tuning: From Configuration to Kernel Parameters is an essential skill in SRE operations. In production environments, mastering these techniques can significantly improve system stability and operational efficiency. Why Nginx Performance Tuning Matters As systems grow in scale and complexity, traditional operations approaches struggle to meet the demands of modern distributed systems. Nginx Performance Tuning helps operations teams: Rapid Problem Resolution: Systematic tools and methods reduce troubleshooting time Improved System Visibility: Establish comprehensive monitoring and observability Proactive Fault Prevention: Identify and fix potential risks before they cause outages Resource Optimization: Allocate and schedule resources efficiently Core Concepts and Principles Basic Concepts The core of Nginx Performance Tuning lies in establishing standardized processes and automated toolchains....
Overview Linux System Call Tracing: strace and ltrace Debugging is an essential skill in SRE operations. In production environments, mastering these techniques can significantly improve system stability and operational efficiency. Why Linux System Call Tracing Matters As systems grow in scale and complexity, traditional operations approaches struggle to meet the demands of modern distributed systems. Linux System Call Tracing helps operations teams: Rapid Problem Resolution: Systematic tools and methods reduce troubleshooting time Improved System Visibility: Establish comprehensive monitoring and observability Proactive Fault Prevention: Identify and fix potential risks before they cause outages Resource Optimization: Allocate and schedule resources efficiently Core Concepts and Principles Basic Concepts The core of Linux System Call Tracing lies in establishing standardized processes and automated toolchains....
Overview The Linux firewall has evolved from ipfwadm → ipchains → iptables → nftables. All are based on the Netfilter framework, but the higher-level syntax and management approach have continuously improved. This article starts from the Netfilter architecture and dives into iptables’ five chains and four tables, nftables’ advantages and usage, NAT/port forwarding, connection tracking, and production performance optimization. Netfilter Framework Architecture Overview Netfilter is a packet processing framework in the Linux kernel that implements packet filtering, address translation, connection tracking, and other functions by mounting hooks at key positions in the kernel network stack....
Overview The process scheduler is a core component of the operating system kernel — it determines which process runs on which CPU and for how long. Linux has used CFS (Completely Fair Scheduler) as its default scheduler since 2.6.23, and after years of evolution, introduced EEVDF (Earliest Eligible Virtual Deadline First) to replace CFS in the 6.6 kernel. This article provides an in-depth analysis of CFS principles, nice/cgroup CPU control, real-time scheduling, CPU affinity, and other core topics, with production tuning experience....
Overview Memory is one of the most precious resources in a Linux system. Understanding how the kernel manages memory not only helps you troubleshoot OOM and memory leak issues in production, but also enables better decisions in capacity planning and performance tuning. This article starts from the virtual memory model and covers core topics including Page Cache, Swap policies, OOM Killer principles, cgroup v2 memory limits, slab/shmem tuning, with multiple production case studies....
Overview The Linux boot process is a precisely orchestrated multi-stage sequence — from firmware power-on self-test to kernel loading, all the way to userspace service startup. Each stage has its specific responsibilities. Understanding the complete boot process not only helps troubleshoot boot failures but also enables boot performance optimization. This article proceeds layer by layer from the firmware level through BIOS/UEFI, GRUB2, initramfs, kernel initialization, and systemd startup, covering boot optimization and kernel crash recovery....