How to investigate which process causes wakeups during laptop sleep-mode in MacOS (or Linux)

When a laptop goes into sleep mode, operating system tries to conserve power by stopping most processes and putting computer in a low-power state. However, sometimes a process may continue to run or periodically wake up computer, preventing it from entering a deep sleep state. This can lead to increased power consumption and a shorter battery life. In this article, we'll explore how to investigate which process is causing wakeups during laptop sleep-mode in MacOS or Linux.

Understanding Power Management Subsystem

Before we dive into how to investigate sleep mode wakeups, it's important to understand power management subsystem in your operating system. Both MacOS and Linux use a similar mechanism to manage power, which is called Advanced Configuration and Power Interface (ACPI). ACPI is an open standard that defines how an operating system can communicate with hardware to manage power.

When a computer goes into sleep mode, operating system sends a signal to hardware to shut down most devices and stop most processes. However, some hardware devices, such as network interface, may need to stay active to receive wake-up signals. Additionally, some processes may be allowed to run periodically to perform maintenance tasks, such as checking for software updates or running system backups.

Understanding basics of ACPI can help you understand how operating system manages power and how to investigate sleep mode wakeups.

Using Terminal to Investigate Sleep Mode Wakeups

One of most powerful tools for investigating sleep mode wakeups is terminal. Both MacOS and Linux have a command-line interface that allows you to interact with operating system and run commands to investigate processes and power usage.

Here are some steps you can take to investigate sleep mode wakeups using terminal −

Step 1: Open Terminal

On MacOS, you can open Terminal by pressing Command+Space and typing "Terminal" into Spotlight search bar. On Linux, you can usually find terminal by pressing Super key (also known as Windows key) and typing "terminal" into search bar.

Step 2: Check Power Management Settings

Before investigating sleep mode wakeups, it's important to make sure your power management settings are properly configured. On MacOS, you can check your power management settings by going to System Preferences > Energy Saver. On Linux, you can check your power management settings by going to Power Management or Battery section of your system settings.

Step 3: Check Power Usage of Running Processes

To check power usage of running processes, you can use "pmset" command on MacOS and "powertop" command on Linux.

On MacOS, open Terminal and type "pmset -g assertions". This command will display a list of all processes that are currently preventing computer from entering sleep mode. Look for any processes that are listed as "Preventing idle sleep" or "Preventing sleep". These processes may be causing wakeups during sleep mode.

On Linux, open Terminal and type "sudo powertop". This command will display a list of all processes that are currently using power on your system. Look for any processes that have a high "Wakeups/second" value. These processes may be causing wakeups during sleep mode.

Step 4: Identify Process Causing Wakeups

Once you've identified a process that may be causing wakeups during sleep mode, you can use "ps" command on both MacOS and Linux to get more information about process.

On MacOS, open Terminal and type "ps -ax | grep [process name]". This command will display information about process, including its process ID (PID). You can use this PID to investigate process further.

On Linux, open Terminal and type "ps -p [process ID]". This command will display detailed information about process, including its CPU usage, memory usage, and other important information.

Step 5: Investigate Process Further

Once you've identified a process that may be causing wakeups during sleep mode, you can investigate it further to determine why it's waking up computer. Here are a few strategies you can use −

• Check process's documentation − Many processes have documentation that can help you understand what they do and why they might be waking up computer during sleep mode. Try searching online for documentation or manuals for process you're investigating.

• Check process's logs − Many processes generate log files that can provide valuable information about what they're doing. Look for log files related to process you're investigating and examine them for clues about why process is waking up computer.

• Disable process − If you can't determine why a process is waking up computer, you may be able to disable it temporarily to see if that resolves issue. Be careful when disabling processes, however, as some processes are critical for proper functioning of operating system.

• Contact process's developer − If you can't determine why a process is waking up computer and you believe it's a bug or a design flaw, you may be able to contact developer of process for assistance. Look for contact information on developer's website or in process's documentation.

In addition to steps outlined above, there are other tools and techniques that can be helpful for investigating sleep mode wakeups on MacOS and Linux.

On MacOS, Activity Monitor application can provide detailed information about running processes and their power usage. To open Activity Monitor, press Command+Space and type "Activity Monitor" into Spotlight search bar. In Activity Monitor, you can sort processes by their energy impact, CPU usage, and other metrics to identify processes that may be causing wakeups during sleep mode.

On Linux, "top" command can provide real-time information about running processes and their resource usage. Open Terminal and type "top" to launch "top" command. By default, "top" shows most CPU-intensive processes, but you can press "P" to sort by other metrics, such as memory usage or process ID.

Another helpful tool for investigating sleep mode wakeups on both MacOS and Linux is "dmesg" command. This command displays kernel ring buffer, which contains information about system events and errors. If a process is waking up computer due to a hardware error or other issue, it may be recorded in kernel ring buffer. To view kernel ring buffer, open Terminal and type "dmesg".

Finally, it's worth noting that some processes are designed to wake up computer periodically, even during sleep mode. For example, software update processes, backup processes, and anti-virus scans may be scheduled to run during sleep mode to minimize their impact on system performance during regular use. If you've investigated your running processes and can't identify any that are causing wakeups during sleep mode, it may be worthwhile to review your scheduled tasks and determine whether any of them are waking up computer.

Conclusion

Investigating sleep mode wakeups can be a challenging task, but with right tools and techniques, you can identify processes that are causing issue and take steps to address it. By using terminal and understanding power management subsystem in your operating system, you can gain valuable insights into processes that are running on your computer and their power usage. With this information, you can optimize your power management settings and ensure that your laptop is running as efficiently as possible.