5.6 Memory Statistics

Data type: vm_statistics_data_t

This structure is returned in vm_stats by the vm_statistics function and provides virtual memory statistics for the system. It has the following members:

long pagesize

The page size in bytes.

long free_count

The number of free pages.

long active_count

The umber of active pages.

long inactive_count

The number of inactive pages.

long wire_count

The number of pages wired down.

long zero_fill_count

The number of zero filled pages.

long reactivations

The number of reactivated pages.

long pageins

The number of pageins.

long pageouts

The number of pageouts.

long faults

The number of faults.

long cow_faults

The number of copy-on-writes.

long lookups

The number of object cache lookups.

long hits

The number of object cache hits.

Function: kern_return_t vm_statistics (vm_task_t target_task, vm_statistics_data_t *vm_stats)

The function vm_statistics returns the statistics about the kernel’s use of virtual memory since the kernel was booted. pagesize can also be found as a global variable vm_page_size which is set at task initialization and remains constant for the life of the task.