Installing a Paravirtualized DomU on Xen Xen remains a solid hypervisor choice for specific workloads, though KVM dominates most Linux distributions today. This guide covers installing a paravirtualized DomU on Xen using modern tooling and Rocky Linux 9, which requires specific kernel parameters during installation. Why Paravirtualization Matters Paravirtualized guests communicate directly with the hypervisor…
How the Linux Kernel Collects Task Stats Data The Linux kernel provides the taskstats API to monitor detailed per-task statistics, including I/O wait time. Understanding how these metrics are collected gives you insight into process behavior and helps diagnose performance issues. The Problem with Direct Measurement One of the most useful metrics is blkio_delay_total —…
Picking Your First Programming Language Choosing your first programming language matters, but it’s not the career-defining decision some make it out to be. What matters more is that you pick something reasonable and start building. That said, some choices will save you months of frustration. Know What You’re Optimizing For Before you evaluate languages, answer…
vimtutor: The Vim Built-in Tutorial vimtutor is the best way to learn Vim basics. Most tutorials on the web pale in comparison to the interactive lessons built into Vim itself. Yet many newcomers to Linux don’t realize they can run an editor tutorial directly from the command line. Here’s what vimtutor teaches and why you…
How sched_setaffinity Works Inside the Linux Kernel CPU affinity allows you to bind a process or thread to specific CPU cores, which is useful for reducing cache misses, improving performance isolation, and managing NUMA locality. The sched_setaffinity() system call is the primary mechanism for this in Linux. Understanding how it works at the kernel level…
Client-Side Routing with AngularJS and ASP.NET MVC AngularJS routing enables you to build single-page applications by splitting views dynamically based on URL patterns. Unlike ASP.NET MVC’s server-side routing, AngularJS routing happens client-side, eliminating page reloads and improving responsiveness. This approach is particularly useful when you need to display different datasets or views without server round-trips….
Note: This post covers Linux fundamentals. Core concepts remain valid, but some commands and package names may differ on modern distributions. See your distro’s documentation for current details. Linux is a great platform for software development targeting servers or backends. In general, working on Linux is very productive. The problem that beginners on Linux face…
SSD is common for VPS and PaaS virtual machines for higher I/O performance. Now, it is coming to shared hosting too. DreamHost states that “Now with solid state drives (SSDs), our standard web hosting loads pages 200% faster”. We ourselves are happy to know this performance improvement with the price kept the same. Good work,…
Note: This post covers Linux fundamentals. Core concepts remain valid, but some commands and package names may differ on modern distributions. See your distro’s documentation for current details. Having to go the the server room to reset servers is the most headache thing for admins managing a cluster of Linux servers in a remote site….
Linux Kernel Video Mode Configuration for Modern Boot Protocols The Linux kernel supports video mode configuration at boot time, though the methods vary depending on your boot protocol and UEFI/BIOS setup. Modern systems typically use EFI boot with KMS (Kernel Mode Setting), but you may still need to configure framebuffer settings in certain scenarios. Understanding…
Hadoop Cluster Setup Hadoop 2.x introduced YARN (Yet Another Resource Negotiator), a major architectural overhaul that decouples resource management from MapReduce job scheduling. This post covers setting up a basic Hadoop 2.x cluster with one NameNode/ResourceManager and multiple DataNodes/NodeManagers. Note: Hadoop 2.x reached end-of-life in 2016. For production use, deploy Hadoop 3.x or later, which…
Outdated Guide: This guide covers Fedora 20 which reached end-of-life many years ago. For current Fedora docs, visit Fedora Docs. Core concepts remain applicable but package names and paths may differ. In this post, creating a file-backed virtual block device (VBD) and installing Fedora 41 in the Xen DomU via internet will be introduced. This…
Historical Reference: This post covers Xen virtualization from 2014. While Xen is still used in production (e.g., AWS EC2, Citrix Hypervisor), KVM has become the default hypervisor for most Linux distributions. For modern virtualization, see KVM documentation or container-based solutions like Docker and Kubernetes. I ever introduced [[installing-xen-domain-0-on-fedora-17]] as the first try to use the…
Note: This post covers Linux fundamentals. Core concepts remain valid, but some commands and package names may differ on modern distributions. See your distro’s documentation for current details. Programs may want to catch the kill signals sent by the kill command in C programs on Linux so that it can gracefully shutdown itself before it…
Note: This post covers WordPress configuration or PHP tips. Most remain applicable to modern WordPress (6.x). See WordPress Developer Docs for current best practices. WordPress can be very fast after some effort on performance optimization with the help from its plenty of plugins. Possible ways include using cache to cut down the number of database…
Error handling and resource management are pervasive in programs. RAII originated in C++ is great. With RAII, it is much easier to write easy-to-read code that allocats/deallocats resources in the constructor/destructors. By representing a resource with a local object, we are sure that local object’s destructor will release the resource and will not forget to…
Note: This post covers C/C++ programming and debugging fundamentals. Core concepts remain valid. For current references, see cppreference.com and GDB documentation. Before statically linking you C and C++ programs, you should be aware of the drawbacks of the static linking especially with glibc. There are some good discussions already: with glibc you’re linking static programs…
Managing Xen Dom0’s CPU and Memory Xen remains in production use at scale (AWS EC2, Citrix Hypervisor, cloud providers), though KVM has become the default hypervisor for most Linux distributions. This guide covers Dom0 resource management for operators maintaining Xen environments. Dom0 performance directly affects the entire system. Since disk and network drivers run on…
Note: This post covers Linux fundamentals. Core concepts remain valid, but some commands and package names may differ on modern distributions. See your distro’s documentation for current details. Software Engineering Advice from Building Large-Scale Distributed Systems by Jeff Dean. You can download the slides from Software Engineering Advice from Building Large-Scale Distributed Systems by Jeff…
C++ References cppreference.com is the authoritative reference for C++ language and standard library documentation. It covers all C++ standards from C++98 through C++26, with clear examples and cross-references. Use this as your primary reference. The official C++ standard drafts are available through the C++ standards committee. While the final standards require purchase, draft versions and…