PPT Slide
Memory-mapped File I/O
- Figure 11.25: Differentiates between persistent VM data (the mapped file) and transient VM data (the file on disk).
- Figure 11.27: Sample file mapping code.
- Figure 11.26: Effects of the MapFile() call.
- Advantages to file mapping:
- Fewer system calls/unit of I/O (well, sort of -- the page fault handler is still calling the OS on a page miss).
- Fewer copies of file blocks in buffers (Figure 11.28).
- “Instant” view of the changed data (unlike explicit I/O, which is usually atomic).
Skip section 11.11.4 (IBM 801 discussion).