How to use the command taskset (with examples)

Taskset is a command used to get or set a process’ CPU affinity or start a new process with a defined CPU affinity. It allows users to bind a process to a specific CPU or set of CPUs, providing more control and optimization over how processes utilize the CPU resources.

Use case 1: Get a running process’ CPU affinity by PID

Code:

taskset --pid --cpu-list pid

Motivation: This use case is useful when you want to check which CPUs are currently assigned to a running process. It helps in understanding the CPU utilization and can be helpful during performance analysis or debugging.

Explanation:

• --pid: Specifies that the process’ CPU affinity should be retrieved.
• --cpu-list pid: Specifies the PID (Process ID) of the running process for which CPU affinity needs to be retrieved.

Example output:

CPU affinity for process with PID 1234 is CPU0, CPU1, CPU2.

Use case 2: Set a running process’ CPU affinity by PID

Code:

taskset --pid --cpu-list cpu_id pid

Motivation: This use case is beneficial when you want to bind a running process to a specific CPU or set of CPUs. By controlling the CPU affinity, you can optimize the process’ execution and improve performance.

Explanation:

• --pid: Specifies that the process’ CPU affinity should be set.
• --cpu-list cpu_id pid: Specifies the CPU or CPUs to bind the process to. cpu_id represents the CPU ID or range of IDs, and pid is the PID (Process ID) of the running process.

Example output:

Set CPU affinity for process with PID 1234 to CPU2, CPU3.

Use case 3: Start a new process with affinity for a single CPU

Code:

taskset --cpu-list cpu_id command

Motivation: This use case is useful when you want to start a new process and explicitly assign it to a specific CPU. By binding a process to a particular CPU, you can ensure that it always executes on that CPU, which can be beneficial in scenarios where CPU-specific optimizations or dependencies are required.

Explanation:

• --cpu-list cpu_id: Specifies the CPU to bind the new process to. cpu_id represents the CPU ID.
• command: Represents the command to execute as the new process.

Example output:

New process started with affinity for CPU3.

Use case 4: Start a new process with affinity for multiple non-sequential CPUs

Code:

taskset --cpu-list cpu_id_1,cpu_id_2,cpu_id_3 command

Motivation: This use case is helpful when you want to start a new process and bind it to multiple non-sequential CPUs. By specifying multiple CPUs, you can distribute the workload of the process across these CPUs, improving parallelism and performance.

Explanation:

• --cpu-list cpu_id_1,cpu_id_2,cpu_id_3: Specifies the non-sequential CPUs to bind the new process to. cpu_id represents the CPU IDs, separated by commas.
• command: Represents the command to execute as the new process.

Example output:

New process started with affinity for CPUs CPU1, CPU3, CPU5.

Use case 5: Start a new process with affinity for CPUs 1 through 4

Code:

taskset --cpu-list cpu_id_1-cpu_id_4 command

Motivation: This use case is useful when you want to start a new process and bind it to a range of CPUs. By specifying a range of CPUs, you can ensure that the new process utilizes a specific set of CPUs, enhancing parallelism and optimizing resource utilization.

Explanation:

• --cpu-list cpu_id_1-cpu_id_4: Specifies the range of CPUs (from cpu_id_1 to cpu_id_4) to bind the new process to. cpu_id_1 and cpu_id_4 represent the starting and ending CPU IDs of the range.
• command: Represents the command to execute as the new process.

Example output:

New process started with affinity for CPUs CPU1, CPU2, CPU3, CPU4.

Conclusion:

The taskset command provides flexibility in managing CPU affinity for processes. Whether you want to retrieve or set CPU affinity for a running process or start a new process with specific CPU affinity, taskset enables you to optimize CPU resource utilization and enhance overall system performance. By leveraging taskset, you can fine-tune the execution of processes on different CPUs based on your specific requirements.