Performance

Got a busy system that comes to a halt due it being too busy? In this article we look at troubleshooting issues related to CPU usage. Monitoring CPU usage The tool top might be the most familiar tool to monitor CPU or memory usage. A good alternative is the pidstat tool. It can be using an interval and easily show active processes, followed by a summary. # pidstat 3 Linux 6.

Network connectivity starts at a device that links the system to a network, and for Linux systems that is no different. Depending on the physical layer, such as Ethernet of Wi-Fi, the transactions between be better or worse. Besides physical limitations, there is congestion and packet loss that may introduce issues. In this section we look at troubleshooting network performance issues, tooling, and examples. Interfaces The first step is to learn what links we have towards the network.

Physical RAM is used to store information. Linux divides this RAM into smaller chunks, named memory pages. When there is no more normal memory available, the Linux kernel might need to temporarily store information aside. This is called paging or swap space. During the process of paging, memory pages will be moved from the RAM to the disk. This way memory is freed up for active processes, while older information is temporarily stored on the disk.

Learn how to use curl to test if your web server is properly caching static files

Introduction Each Linux system has a bunch of processes running. Most of these processes might be familiar to you if you regularly use a command like ps or top to display them. Processes may look like just an item in a list. They are actually complicated pieces of code that are tamed by a memory manager. To truly understand how your system is running, knowledge of process (or memory) management is of great help.

DNS Configuration on Linux We often don’t realize the importance of DNS, or name resolving in our infrastructure. The impact when things go (slightly) wrong is huge. Time to have a good look at improving our DNS configuration. How DNS resolving works When your Linux system needs to know the IP address of a particular host, it will use gethostbyname(3) function. This will use the nsswitch configuration stored in /etc/nsswitch.conf. For the related hosts line, it will determine how to do resolving.

The Linux Audit framework is a powerful tool to audit system events. From running executables up to system calls, everything can be logged. However, all this audit logging comes at the price of decreased system performance. Let’s have a look at how we can optimize our audit rules. Performance tips Good auditd performance will reduce stress on the Linux kernel and lower its impact. Before changing anything to your system, we suggest benchmarking your system performance before and after.

Recently we changed our corporate website into a “HTTPS only” version. Most of the content is not secret information, still we have some sensitive areas. The ordering section and downloads, and additional our portal. While some areas were already covered with a lock, we felt it was time to make the jump to cover it all. Additionally, we believe that we doing everything we can on our website, practicing security hardening ourselves.