Page Cache

Definitions

1. A region of main memory managed by the OS kernel that caches recently read file pages (typically 4 KB blocks) from disk, so that subsequent reads of the same data are served from RAM at memory speed rather than incurring disk I/O. On Linux, free RAM is aggressively used for page cache and reclaimed under memory pressure.

   In plain English: The operating system's trick of keeping recently read file data in RAM so the next time you need it, it's already there instead of on the slow disk.

   Example: "The second run of the benchmark was 50× faster because the entire dataset was already warm in the page cache."

Related Terms

• Swap
• DMA
• Cache
• Memory Allocation
• Apache Arrow
• Memory Pool
• Page Fault
• Memory Pressure
• Microkernel
• Named Pipe
• Physical Memory
• Process Group
• Type Punning
• Write Back