How to use the command 'vm_stat' (with examples)
- Osx
- December 25, 2023
The ‘vm_stat’ command is used to display virtual memory statistics on a Unix-like operating system. It provides information about various aspects of virtual memory usage, including page-ins, page-outs, memory pressure, and more.
Use case 1: Display virtual memory statistics
Code:
vm_stat
Motivation: This use case is helpful when you want to quickly get an overview of the current virtual memory statistics on your system. It can be useful for troubleshooting performance issues or monitoring memory usage.
Explanation: The command ‘vm_stat’ without any arguments will display virtual memory statistics in real-time. It provides information such as the number of active, inactive, wired, and free pages, as well as page-ins and page-outs, in the virtual memory system.
Example output:
Mach Virtual Memory Statistics: (page size of 4096 bytes)
Pages free: 10000.
Pages active: 20000.
Pages inactive: 15000.
Pages speculative: 5000.
Pages throttled: 0.
Pages wired down: 30000.
Pages purgeable: 0.
"Translation faults": 250000.
Pages copy-on-write: 10000.
Pages zero filled: 15000.
Pages reactivated: 0.
Pages purged: 0.
File-backed pages: 50000.
Anonymous pages: 45000.
Pages stored in compressor: 10000.
Pages occupied by compressor: 5000.
Decompressions: 20000.
Compressions: 0.
Pageins: 1000.
Pageouts: 500.
Swapins: 0.
Swapouts: 0.
Use case 2: Display reports every 2 seconds for 5 times
Code:
vm_stat -c 5 2
Motivation: This use case is useful when you want to monitor the virtual memory statistics over a period of time. By specifying the interval and count, you can obtain multiple reports at regular intervals.
Explanation: The ‘-c’ option is used to specify the count, i.e., the number of reports to be displayed. In this case, we set it to 5, which means we will get 5 reports. The second argument, ‘2’, specifies the interval between each report in seconds.
Example output:
Mach Virtual Memory Statistics: (page size of 4096 bytes)
Pages free: 10000. 10000. 10000. 10000. 10000.
Pages active: 20000. 20000. 20000. 20000. 20000.
Pages inactive: 15000. 15000. 15000. 15000. 15000.
Pages speculative: 5000. 5000. 5000. 5000. 5000.
Pages throttled: 0. 0. 0. 0. 0.
Pages wired down: 30000. 30000. 30000. 30000. 30000.
Pages purgeable: 0. 0. 0. 0. 0.
"Translation faults": 250000. 250000. 250000. 250000. 250000.
Pages copy-on-write: 10000. 10000. 10000. 10000. 10000.
Pages zero filled: 15000. 15000. 15000. 15000. 15000.
Pages reactivated: 0. 0. 0. 0. 0.
Pages purged: 0. 0. 0. 0. 0.
File-backed pages: 50000. 50000. 50000. 50000. 50000.
Anonymous pages: 45000. 45000. 45000. 45000. 45000.
Pages stored in compressor: 10000. 10000. 10000. 10000. 10000.
Pages occupied by compressor: 5000. 5000. 5000. 5000. 5000.
Decompressions: 20000. 20000. 20000. 20000. 20000.
Compressions: 0. 0. 0. 0. 0.
Pageins: 1000. 1000. 1000. 1000. 1000.
Pageouts: 500. 500. 500. 500. 500.
Swapins: 0. 0. 0. 0. 0.
Swapouts: 0. 0. 0. 0. 0.
Conclusion:
The ‘vm_stat’ command is a powerful tool for monitoring virtual memory statistics on a Unix-like operating system. By using different options, you can customize the output and obtain valuable insights into memory usage, page-ins, and page-outs. Whether you need real-time information or reports over a specific period, ‘vm_stat’ provides the necessary functionality to analyze virtual memory utilization.
