Key Language Differences Between Java and C++ Java and C++ share common ancestry but diverged significantly in design philosophy. Java prioritizes safety and simplicity, while C++ emphasizes performance and flexibility. Here are the major language-level differences you’ll encounter when working with both: Memory Management and Pointer Handling Java eliminated pointers entirely in favor of automatic…
I try to find some Hashing libraries for C and find several good ones. The hsearch function in the GNU C library. There are other methods to organize information which later should be searched. The costs of insert, delete and search differ. One possible implementation is using hashing tables. The following functions are declared in…
Debugging with Vim and cgdb Using Vim for programming pairs well with cgdb, a curses-based frontend to gdb that keeps the source code visible while debugging. Unlike pure gdb, cgdb lets you navigate code naturally while issuing debug commands without context switching. Why cgdb over gdb alone When debugging with raw gdb, you lose sight…
“The C language provides no built-in facilities for performing such common operations as input/output, memory management, string manipulation, and the like. Instead, these facilities are defined in a standard library, which you compile and link with your programs. The GNU C library, described in this document, defines all of the library functions that are specified…
Generating Mixed Source and Assembly Lists with GCC When debugging and optimizing C/C++ programs, you often need to see how the compiler translates your source code into assembly. Generating a mixed source and assembly listing makes this analysis straightforward. Basic Approach Use these GCC compiler flags: gcc -Wa,-adhln -g source_code.c -o binary > assembly_list.s The…
Browser-Based Remote System Resource Monitor Java Applets are deprecated and no longer supported in modern browsers. This post documents a legacy approach; modern implementations use web technologies instead. Historical Context This project implemented a browser-based system resource monitor using Java Applets, establishing Socket connections to remote hosts to fetch system metrics and render them dynamically…
Microsoft Algorithm Interview Questions This is a collection of classic algorithm problems from Microsoft technical interviews. These questions test fundamental data structures, string manipulation, and problem-solving approaches. Below are the problems with explanations and code solutions. 1. Differences Between Linked Lists and Arrays Key differences: Memory allocation: Arrays use contiguous memory; linked lists use scattered…
Xen Domain-U Installation with PXE Booting Xen remains in production use across cloud providers (AWS EC2, Citrix Hypervisor) and large infrastructure deployments, though KVM has become the default hypervisor for most Linux distributions. This guide covers installing a Fedora Domain-U on a Xen Dom0 using PXE boot, applicable to current Fedora releases. Prerequisites A working…
About iptables vs firewalld Modern Fedora (29+) uses firewalld by default instead of the legacy iptables service. If you’re working with an older system or one configured for iptables, the concepts here still apply, but you should first check what’s actually managing your firewall: systemctl status firewalld systemctl status iptables If firewalld is active, use…
Installing and Configuring Xen on Fedora Xen remains relevant for certain production workloads, particularly in cloud infrastructure (AWS EC2, Citrix Hypervisor) and enterprise environments requiring strong VM isolation. However, most Linux distributions now default to KVM for virtualization due to simpler setup and broader ecosystem support. If you’re evaluating hypervisors, consider KVM or container-based solutions…
Flushing Linux File System Caches Dropping file system caches reclaims memory for applications. Linux kernels 2.6.16+ provide a /proc/sys/vm/drop_caches interface to trigger cache eviction. This is safe — the kernel only frees clean cache pages and unreferenced inodes/dentries. Dirty data stays in memory until explicitly synced to disk. Two-Step Cache Drop Process Step 1: Sync…
Xen Virtualization: Historical Context and Modern Alternatives This post describes Xen DomU setup procedures from the early 2010s. While Xen remains critical infrastructure for cloud providers like AWS EC2 and Citrix Hypervisor, it’s rarely deployed for new on-premises virtualization projects. For modern Linux virtualization, consider: KVM/QEMU: The default hypervisor in most Linux distributions, better community…
pgrep and pkill: Process Management Commands pgrep and pkill are essential tools for finding and signaling processes by name and attributes. They’re far more precise than grepping ps output and should be your go-to for process management scripts and one-liners. pgrep: Find Process IDs pgrep searches running processes and outputs matching PIDs. All selection criteria…
LVM-backed storage for Xen DomU LVM logical volumes are a practical choice for Xen guest storage. They support dynamic resizing, snapshots, and efficient cloning — capabilities that make capacity management and guest provisioning straightforward compared to fixed disk images. This guide covers creating and configuring LVM-backed virtual block devices (VBDs) for Xen DomU instances. Creating…
LVM Snapshots for Fast Virtual Machine Cloning LVM snapshots provide an efficient way to duplicate virtual machines in seconds rather than minutes. Instead of copying an entire filesystem, snapshots leverage copy-on-write semantics—physical blocks are only duplicated when the source or snapshot is modified. This approach works well for any LVM-backed virtualization platform, though Xen is…
Xen Hypervisor Source Code Organization Xen remains a production hypervisor used by AWS EC2, Citrix Hypervisor, and other cloud providers, though most general-purpose Linux distributions have shifted toward KVM as their default. If you’re working with Xen in production or developing drivers, understanding its source code layout is essential. Top-Level Directory Structure The Xen source…
Duplicating and Backing Up LVM-Backed VMs from a Remote Server LVM snapshots provide a fast, efficient way to duplicate virtual machines across servers. This technique applies to any LVM-backed hypervisor including Xen, KVM, and Proxmox. The process uses LVM snapshots on the source server, then transfers the snapshot image to the destination using standard Unix…
Checking Firmware Version in Linux The firmware (BIOS/UEFI) on your system contains critical hardware settings and boot information. Knowing your firmware version is essential for updates, compatibility checks, and troubleshooting. Here’s how to find it. Using dmidecode dmidecode is the standard tool for reading the Desktop Management Interface (DMI) table, which stores hardware and firmware…
Historical Context and Modern Alternatives This post covers Xen virtualization benchmarks from 2013. While Xen remains in production use (AWS EC2, Citrix Hypervisor), KVM has become the default hypervisor for most Linux distributions. For current production environments, evaluate KVM with libvirt, direct container solutions (Docker, Kubernetes), or cloud-native platforms. This post is preserved for historical…
Setting Up Xen Dom0 on Fedora Xen remains a production-grade hypervisor used in enterprise environments (AWS EC2, Citrix Hypervisor), though KVM has become the default for most Linux distributions. This guide covers building a stable Xen Dom0 on current Fedora releases using modern kernel sources. Hardware Considerations This guide assumes server-class hardware with: Intel or…