You have probably experienced this before: you use tools like htop, free -h, or take a look at /proc/meminfo on your Linux server and find that the RAM usage differs. Don’t worry, you’re not alone! Many developers encounter this question. We want to help you understand these differences and shed light on the Linux memory management.

It can also happen in the web interface that you see something different from what is shown in htop.

Understanding Linux Memory Management

Linux manages the Random Access Memory (RAM) in a complex way to ensure efficient resource utilization. The memory is not only used by active applications but also for caching data to improve system performance. This often leads to confusion when reading the actual memory usage.

Why htop shows something different from free -h and /proc/meminfo

  • htop: This interactive tool shows the processes and their memory usage in real-time. htop classifies memory into different categories (e.g., used, free, buffered, cached), which can result in higher utilization values since it also includes memory reserved for caching and buffering.
  • free -h: The free command provides an overview of the total memory and the used, free, and memory used by buffers and cache. The -h option ensures a easily readable output. The discrepancy with htop can be due to the different interpretation of „free“ and „available“.
  • /proc/meminfo: This virtual file contains detailed information about the memory status of the system. It is the most comprehensive source of memory data, providing numerous entries for different memory types and reservations. However, interpreting this data requires in-depth technical understanding.

The differences in displaying RAM usage between different tools result from their different approaches to classifying and measuring memory. Deep understanding of Linux memory management helps in correctly interpreting and utilizing this information. Our developments aim to provide you with precise and useful tools to optimize the management of your virtual servers.