In this section, we will explore the essential tools and techniques for monitoring and tuning the performance of a Linux system. This is crucial for maintaining system health, ensuring optimal performance, and preemptively addressing potential issues.

1. System Monitoring: The process of continuously observing system performance and resource usage.
2. Performance Tuning: The practice of adjusting system settings and configurations to improve performance.

• top: A command-line utility that provides a dynamic, real-time view of system processes.
• htop: An enhanced version of top with a more user-friendly interface.

Example: Using top

• Explanation: Running top displays a list of processes, CPU usage, memory usage, and other system statistics.

Example: Using htop

• Explanation: htop provides a more interactive and colorful display, allowing for easier navigation and process management.

• vmstat: Reports information about processes, memory, paging, block IO, traps, and CPU activity.

Example: Using vmstat

• Explanation: This command will display system performance statistics every 5 seconds.

• iostat: Reports CPU and I/O statistics for devices and partitions.

Example: Using iostat

• Explanation: This command provides extended statistics every 5 seconds.

• sar: Collects, reports, and saves system activity information.

Example: Using sar

• Explanation: This command will report CPU usage every 5 seconds, 5 times.

• netstat: Displays network connections, routing tables, interface statistics, masquerade connections, and multicast memberships.

Example: Using netstat

• Explanation: This command lists all listening ports and their respective services.

• Adjusting CPU Scheduling: Modify the CPU scheduler to prioritize certain processes.
• Example: Using nice and renice to change process priority.

Example: Using nice

• Explanation: This command runs command with a lower priority.

Example: Using renice

• Explanation: This command changes the priority of the process with PID 1234.

• Swappiness: Adjust the swappiness value to control the tendency of the kernel to move processes out of physical memory and onto the swap disk.
• Example: Changing swappiness value.

Example: Adjusting Swappiness

• Explanation: This command sets the swappiness value to 10, making the system less likely to use swap space.

• I/O Scheduler: Choose an appropriate I/O scheduler for your workload.
• Example: Changing the I/O scheduler.

Example: Changing I/O Scheduler

• Explanation: This command sets the I/O scheduler for the sda device to noop.

• TCP Window Size: Adjust the TCP window size to improve network performance.
• Example: Changing TCP window size.

Example: Adjusting TCP Window Size

• Explanation: These commands set the maximum receive and send buffer sizes for TCP connections.

1. Use top or htop to monitor the system's CPU and memory usage.
2. Identify the top 5 processes consuming the most resources.

Solution

• Explanation: Observe the output and note the processes with the highest CPU and memory usage.

1. Run a CPU-intensive task with a lower priority using nice.
2. Change the priority of an existing process using renice.

Solution

• Explanation: The nice command runs the dd command with a lower priority, and renice changes the priority of the process with PID 1234.

1. Check the current swappiness value.
2. Change the swappiness value to 20.

Solution

• Explanation: The first command checks the current swappiness value, and the second command sets it to 20.

In this section, we covered essential tools and techniques for monitoring and tuning the performance of a Linux system. We explored various commands such as top, htop, vmstat, iostat, sar, and netstat for system monitoring. Additionally, we discussed performance tuning techniques for CPU, memory, disk I/O, and network. Practical exercises were provided to reinforce the learned concepts. Understanding and applying these tools and techniques will help you maintain a healthy and efficient Linux system.