function::cpu_clock_s - Linux

Overview

The function::cpu_clock_s command measures the time elapsed since an arbitrary point in the past using the CPUs hardware time stamp counter. It’s useful for performance measurements, benchmarking, and precise timing of program execution.

Syntax

function::cpu_clock_s()

Options/Flags

This command has no options or flags.

Examples

# Example 1: Simple elapsed time measurement
start=$(function::cpu_clock_s)
# Perform some tasks here
end=$(function::cpu_clock_s)
elapsed=$(echo "$end - $start" | bc -l)
echo "Elapsed time: $elapsed seconds"

# Example 2: Compare execution times between two functions
function slow_function() { sleep 3; }
function fast_function() { sleep 1; }

slow_start=$(function::cpu_clock_s)
slow_function
slow_end=$(function::cpu_clock_s)
slow_time=$(echo "$slow_end - $slow_start" | bc -l)

fast_start=$(function::cpu_clock_s)
fast_function
fast_end=$(function::cpu_clock_s)
fast_time=$(echo "$fast_end - $fast_start" | bc -l)

echo "Slow function: $slow_time seconds"
echo "Fast function: $fast_time seconds"

if ((slow_time > fast_time)); then
  echo "Slow function takes longer to execute"
else
  echo "Fast function takes longer to execute"
fi

Common Issues

• Incorrectly pairing start and end results: Ensure you use the same variable when recording the start and end timestamps to avoid inaccurate elapsed time calculations.

Integration

The function::cpu_clock_s command can be used in conjunction with other commands to create powerful timing and measurement tools. For example, it can be used with the time command to measure the execution time of a specific command or script:

time command_or_script &> /dev/null
start=$(function::cpu_clock_s)
command_or_script
end=$(function::cpu_clock_s)
elapsed=$(echo "$end - $start" | bc -l)
echo "Elapsed time: $elapsed seconds"

Related Commands

• date: Provides time and date information.
• time: Measures the execution time of commands or scripts.
• perf: Monitors and profiles system performance, including CPU usage.