pcstat gets page cache statistics for files on Linux using the mincore(2) syscall. It was created to help users, particularly Apache Cassandra users, determine if data is being cached. The tool reads page cache information directly from the kernel, providing a direct view of caching behavior. It leverages the mincore() system call, a low-level interface for accessing memory mapping statistics.
pcstat offers a simple and direct way to inspect page cache stats, avoiding reliance on higher-level tools. It includes options for JSON output, terse output for scripting, and histogram output for visual analysis (with limitations). The project is relatively self-contained, with binaries available for download. The tool provides options for specifying files, using basenames, and customizing the output format.
- File-Based Inspection: Analyzes page cache statistics for individual files specified as command-line arguments.
- JSON Output: Generates machine-readable JSON output for easy integration with other tools and scripts.
- Terse Mode: Provides a concise, machine-parseable output format suitable for scripting and processing.
- Histogram Output: Displays a visual representation of page cache usage using Unicode block characters.
- Cross-Platform Binary: Pre-built binaries are available for both 32-bit and 64-bit x86 systems.
- Flexible Arguments: Supports various command-line arguments to customize the output and behavior.
- Developer-Friendly: Simple to build and use, with clear documentation and usage examples.
The project has been available since 2014 and has received recent commits, indicating ongoing maintenance. The documentation is reasonably comprehensive, including usage instructions, examples, and building guidelines. While not actively developed at a rapid pace, it appears stable and reliable for its core functionality. Community presence is limited but the project is well-documented.
pcstat is beneficial for system administrators and developers seeking to understand and optimize data caching performance on Linux systems. It is particularly useful for diagnosing performance bottlenecks related to disk I/O and validating caching configurations. By providing detailed page cache statistics, it allows for informed decisions regarding system tuning and resource allocation, offering a lightweight alternative to more complex monitoring solutions.