vm_stat — show
Mach virtual memory statistics
vm_stat |
[[-c count]
interval] |
vm_stat displays Mach virtual memory
statistics. meminfo(1) is the modern, preferred tool for
inspecting physical memory usage and should be used instead of
vm_stat where possible. If the optional
interval is specified, then
vm_stat will display the statistics every
interval seconds. In this case, each line of output
displays the change in each statistic (an interval
count of 1 displays the values per second). However, the first line of
output following each banner displays the system-wide totals for each
statistic. If a count is provided, the command will
terminate after count intervals. The following values
are displayed:
- Pages free
- the total number of free pages in the system.
- Pages active
- the total number of pages currently in use and pageable.
- Pages inactive
- the total number of pages on the inactive list.
- Pages speculative
- the total number of pages on the speculative list.
- Pages throttled
- the total number of pages on the throttled list (not wired but not
pageable). These are also included in Pages wired down
below.
- Pages wired down
- the total number of pages wired down. That is, pages that cannot be paged
out.
- Pages purgeable
- the total number of purgeable pages.
- Translation faults
- the number of times the "vm_fault" routine has been called.
- Pages copy-on-write
- the number of faults that caused a page to be copied (generally caused by
copy-on-write faults).
- Pages zero filled
- the total number of pages that have been zero-filled on demand.
- Pages reactivated
- the total number of pages that have been moved to the active list, e.g.
from the inactive list or when a page is unwired.
- Pages purged
- the total number of pages that have been purged.
- File-backed pages
- the total number of resident pages that are file-backed, excluding those
that are wired down. File-backed pages can be evicted and refetched under
pressure and do not need to be compressed.
- Anonymous pages
- the total number of resident pages that are anonymous, that is, not
file-backed. Anonymous pages may be compressed under pressure. Does not
include pages stored in the compressor (and so not resident) or that are
wired down.
- Pages stored in compressor
- the total number of pages whose contents are stored in the in-memory
compressor pool.
- Pages occupied by compressor
- the total number of pages used by the in-memory compressor pool.
- Decompressions
- the total number of pages that have been decompressed by the VM
compressor.
- Compressions
- the total number of pages that have been compressed by the VM
compressor.
- Pageins
- the total number of requests for pages from a pager (such as the inode
pager). This may include speculative reads.
- Pageouts
- the total number of file-backed pages that have been written back to a
pager.
- Swapins
- the amount of compressed data read back in from swap files, in units of
pages. Because the data is compressed, this is not the number of pages it
expands to.
- Swapouts
- the amount of compressed data written out to swap files, in units of
pages. Likewise, this is not the number of pages that were compressed to
produce it.
Both swap counters also include I/O used for swapfile
maintenance.
If the system supports the ARM Memory Tagging Extension (MTE),
then the following values will additionally be displayed:
- Pages tagged
- the total number of virtual pages which have been assigned memory
tags.
- Pages tagged resident
- the number of tagged pages which are resident in memory.
- Pages tagged compressed
- the number of tagged pages which have been evicted to the compressor.
- Pages tag-storage
- the total number of physical pages which may be used to store memory
tags.
- Pages tag-storage holding tags
- the number of physical pages which are currently being used to store
memory tags.
- Pages tag-storage free
- the number of tag-storage pages which are unused. These are also included
in Pages free above.
- Pages tag-storage non-tag pageable
- the number of tag-storage pages which are being used to store pageable
non-tag data.
- Pages tag-storage non-tag wired
- the number of tag-storage pages which are being used to store wired
non-tag data.
- Bytes of compressed tags
- the (post-compression) size of memory tags currently held in the
compressor, in bytes.
- Tagged compressions
- the number of tagged pages which have been compressed.
- Tagged decompressions
- the number of tagged pages which have been decompressed.
If interval is not specified, then
vm_stat displays all accumulated statistics along
with the page size.