What's the Best Way to Measure C Function Execution Time on Linux?

Best Way to Measure Function Execution Time in C on Linux

Measuring the execution time of a function is crucial for performance analysis and optimization in C programs. This article addresses how to effectively determine the execution time of a function on a Linux system.

Using boost::chrono to Measure CPU Time

While the boost::chrono library provides various time-related functions, it is not recommended for measuring the execution time of a specific function. The process_user_cpu_clock function measures user-CPU time spent by the current process, which may not accurately represent the function's execution time, especially in a multithreaded environment.

Solution: std::chrono

The recommended approach for measuring function execution time is to use the std::chrono library introduced in C 11. It provides precise time measurements through the std::chrono::high_resolution_clock.

Here's an example of how to measure the execution time of a function using std::chrono::high_resolution_clock:

#include <chrono>
#include <iostream>
#include <thread>

void long_operation() {
    std::this_thread::sleep_for(150ms);  // Simulating a long operation
}

int main() {
    auto t1 = std::chrono::high_resolution_clock::now();
    long_operation();
    auto t2 = std::chrono::high_resolution_clock::now();
    
    auto ms_int = std::chrono::duration_cast<std::chrono::milliseconds>(t2 - t1);
    std::cout << ms_int.count() << "ms\n";
    
    return 0;
}

This code demonstrates the measurement of the execution time of the long_operation function. It prints the execution time in milliseconds.

Additional Notes

• std::chrono::high_resolution_clock provides nanosecond precision, but the actual resolution may vary depending on the system.
• For more details on using std::chrono for time measurement, refer to the C reference or tutorials.
• Benchmarking frameworks like Google's Benchmark can provide additional tools for measuring and comparing the execution time of different functions or code blocks.

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