Storage May 19, 2026

Using Memory-Mapped Files (mmap) for Zero-Copy Target Offset Stitching

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Using Memory-Mapped Files (mmap) for Zero-Copy Target Offset Stitching featured header illustration

Standard file I/O operations require copying data from the network card into kernel buffers, then into user-space memory, and finally onto disk storage.

Each memory copy consumes CPU cycles and introduces system latency.

The mmap Virtual Space Bypass

NextGen DLM leverages memory-mapped files (`mmap` on Unix, `CreateFileMapping` on Windows) to map the target storage bounds directly into the application's virtual address space.

As packets arrive on the parallel TCP sockets, they are written directly into this mapped address space. The OS kernel handles flushing the memory pages directly to disk, completely bypassing the user-space copy bottleneck.