vm_stat:tldr:76b24

The command vm_stat is a built-in utility in macOS that provides information about virtual memory statistics. It displays various statistics related to the memory usage and management on the system.

Running the vm_stat command in the Terminal will display a set of columns representing different aspects of the virtual memory system, such as pageins, pageouts, faults, etc. Here are some key columns and their explanations:

• Mach Virtual Memory Statistics: These columns provide an overview of the virtual memory system's usage and performance.

• Pages free: The number of free pages available for new data or code.

• Pages active: The number of pages that have been recently accessed and are actively used.

• Pages inactive: The number of pages that have been recently accessed but are no longer actively used.

• Pages speculative: The number of pages marked as speculative, which means their content is not fully established yet.

• Pages throttled: The number of pages that have been throttled due to various reasons, such as low memory conditions.

• Pages wired down: The number of pages that are permanently locked in physical memory and cannot be swapped out.

• Pages purgeable: The number of pages that can be purged from memory if necessary.

• Translation Faults: The number of memory access faults that required a translation from virtual to physical memory addresses.

• Copy-on-Write Faults: The number of memory access faults that required a copy of a page instead of directly accessing it.

• Pageins: The number of times a page had to be read from disk into memory.

• Pageouts: The number of times a page had to be written from memory to disk.

By analyzing the information provided by vm_stat, one can get insights into the memory usage patterns, page swapping activity, and overall system performance related to memory management in macOS.