Memory Mapping Example

This repository provides a platform-independent memory mapping. The test driver is a simple implementation of wc -l.

Compilation on Linux/macOS

clang++ memory_mapping.t.cpp memory_mapping.cpp -Wall -Wextra -march=native -O3 -Wpedantic -std=c++17

Compilation on Windows

cl memory_mapping.t.cpp memory_mapping.cpp /std:c++17 /O2 /FA /EHsc /GL /Ob2 /nologo

Performance

I counted the newlines in the source code of CSPICE (https://naif.jpl.nasa.gov/naif/toolkit_C.html) using macOS:

# File-based
$ ./a.out cspice/src/cspice/*.c
# Map-based
$ NZL_USE_MAP=1 ./a.out cspice/src/cspice/*.c

Some timings (nanoseconds):

Using MemoryMapping
79833000
80383000
81283000
77522000

Using file-based I/O
150205000
150359000
149858000
149975000

The memory mapping implementation performs an order of magnitude faster than the file-based implementation (there are ways to make the file-based implementation go faster, but that's not the point of this example).