Mac OS X for Unix Geeks

vm_stat

The vm_stat utility displays virtual memory statistics. Unlike implementations of vm_stat in other Unix systems, it does not default to continuous display. Instead, it displays accumulated statistics.

To obtain a continuous display, specify an interval argument (in seconds), as in vm_stat 1. Figure 8-3 shows the output of vm_stat with no arguments, and Figure 8-4 shows the output of vm_stat 1. Table 8-4 describes the information that vm_stat displays (the item numbers correspond to the callouts in both figures).

Figure 8-3. vm_stat displaying accumulated statistics

Figure 8-4. vm_stat’s continuous output

Table 8-4. Information displayed by vm_stat

Item number	Accumulated mode	Continuous mode	Description
1	Pages free	free	Total free pages
2	Pages active	active	Total pages in use that can be paged out
3	Pages inactive	inac	Total inactive pages
4	Pages wired down	wire	Total pages wired into memory (cannot be paged out)
5	Translation Faults	faults	Number of times vm_fault has been called
6	Pages copy-on-write	copy	Number of faults that resulted in a page being copied
7	Pages zero filled	zerofill	Number of pages that have been zero-filled
8	Pages Reactivated	reactive	Number of pages reclassified from inactive to active
9	Pageins	pagein	Number ...