php-ffi-rdtsc

Expose the __rdtsc CPU cycle counter to user-land using PHP-FFI

Requirements

• x64 platform
• gcc
• php-ffi
• ffi.enable=true or alternatively ffi.enable=preload for the CLI SAPI

Usage

./compile.sh
php example.php

Notes

Given the various caveats with __rdtsc this should be used with great care when trying to measure things.

There also is a PHP extension that provides the same functionality available.

For most cases getrusage() should be preferable.

References

• Wikipedia - Time Stamp Counter
• Microsoft cpp intrinsics __rdtsc
• Intel - How to Benchmark Code Execution Times on Intel® IA-32 and IA-64 Instruction Set Architectures
• Online x64 reference