vmstat(1) General Commands Manual vmstat(1)
NAME
vmstat - Displays virtual memory statistics
SYNOPSIS
vmstat interval [count]
vmstat [-D | -f | -i | -M | -p | -P | -r rad_id | -R | -s | -w]
The vmstat command displays system statistics for virtual memory, processes, trap, and CPU activity.
OPTIONS
Displays debugging information if kmem_debug is set. Displays only statistics about the number of forks since system startup (see the
fork() call). Displays the following virtual memory statistics: # vmstat -i Virtual Memory Statistics: (pagesize = 8192)
procs memory pages intr cpu
r w u act free wire fault cow zero react pin pout in sy cs us sy id
2 82 29 23K 12K 4906 3M 963K 834K 620 710K 0 73 30 391 0 2 98 Displays information about memory usage by buckets. This
information can be used for kernel debugging. Displays statistics for the vm and ubc subsystems for all Resource Affinity Domains (RADs).
Typical output (derived from a single-RAD, single-CPU server) is shown in the following example: # vmstat -p
Total RADs: 1 Total CPUs: 1 Total Ticks: 512
36441297 VM faults 1677 VM kfaults
2115850 VM cowcopy 1677 VM kzfod
0 VM pagesteal 0 VM prewrites
0 VM anon_prewrites 0 VM swap_prewrites
0 VM cleanrecs 0 VM swaprecs
0 VM lmsteal 0 VM lmstealwins
0 VM ffl 0 VM pout_scan
0 VM pout_pagescan 0 VM pout_call
0 VM pout 0 VM pout_target
0 VM pout_burst 12548 VM act_scans
12548 VM act_moves 0 VM lock_fails
0 VM migrations
2547665 VM TOT cowfaults 3813949 VM TOT zfod
0 VM TOT iowrites 0 VM TOT pgwrites
26823910 VM TOT ioreads 0 VM TOT pgreads
1423 VM TOT reactivate
0 UBC allocscans 0 UBC alloceol
0 UBC allocpush 0 UBC allocstole
0 UBC allocseq 0 UBC wacalls
0 UBC wascans 0 UBC waeol
0 UBC prges 0 UBC prgscans
0 UBC prgeol 0 UBC prgburst
0 UBC prgfree 0 UBC mmapfree
79566 UBC wdeny 0 UBC hardsteals
0 UBC stealscans 0 UBC dirtywra
0 UBC reclaim 0 UBC pagesteal
42127497 UBC lookups 41985615 UBC lookuphits
0 UBC ffl 0 UBC lmsteal
0 UBC lmstealwins 0 UBC seqdrain
144957 UBC TOT alloc 0 UBC TOT iowrites
0 UBC TOT reactivate 0 UBC TOT pgwrites
Displays the following accumulated statistics about physical memory use: Sum of the total physical memory in the machine. This statistic
describes how physical memory is clustered. It shows where memory is being used (pal, os, and nvram), the starting and ending pageframes,
and the total amount of memory used. This statistic shows a breakdown of physical memory used by the operating system (such as text, data,
and bss). It contains the starting and ending pageframes, memory usage per category, and total memory used. This statistic provides snap-
shot of where managed physical memory resides when the vmstat command was run. It indicates the the number of pages in the free, active
and inactive queues, the number of wired pages, and the number of pages held in the unified buffer cache (UBC). This statistic describes
the physical pages that are wired in memory. The fields show the number of wired pages in anonymous(vm) memory, the UBC, pages used for
meta data, the kernel malloc pools, contiguous memory, and pages used for page table entries (ptes). The display typically shows: vm and
ubc wired pages meta data, malloc, and contig pages user, kernel, and free ptepages. Displays virtual memory statistics for the specified
Resource Affinity Domain (RAD) only. The rad_id is an integer assigned automatically by the system. Typical output is shown in the follow-
ing example, which has been reformatted for ease of reference: # vmstat -r 0 Virtual Memory Statistics: (pagesize = 8192)
procs memory pages
RAD r w u st sw act actv actu acti free wire wirv wiru fault
0 2 157 27 0 0 31K 4928 18K 8813 24K 6544 3015 0 36M
intr cpu
cow zero react pin pout in sy cs us sy id
2M 3M 1423 26M 0 102 249 229 0 1 99 Displays information for all Resource Affinity Domains (RADs). Typical output is shown
under the -r option. Displays the following accumulated statistics along with the page size: Total number of pages that are currently in
use but can be used for paging. Total number of VM pages that are allocated but are most likely to be used for paging. Total number of
unreferenced (clean) pages that are available for use. Total number of pages that are currently in use and cannot be used for paging (not
a real list). Number of address translation faults that have occurred. Number of copy-on-write page faults, which occur if the requested
page is shared by a parent process and one or more child processes (using the fork function) and if one of the processes needs to modify
the page. In this case, VM loads a new address into the translation buffer and copies the contents of the requested page into the new
address for modification by the process. Number of zero-filled-on-demand page faults, which occur if VM cannot find the page in the inter-
nal data structures and if the requested page is new and has never been referenced. In this case, VM initializes a physical page (the con-
tents of the page are zeroed out) and loads the address into the page table. Number of pages that have been faulted while on the inactive
list. Number of requests for pages from a pager. Number of pages that have been paged out. Number of task and thread context switches.
Number of nonclock device interrupts. Number of system calls called. Appends iowait information to the default output as follows:. Vir-
tual Memory Statistics: (pagesize = 8192)
procs memory pages intr cpu
r w u act free wire fault cow pin pout in sy cs us sy id iowait
2 82 29 23K 12K 4905 3M 963K 710K 0 73 30 391 0 2 98 0
DESCRIPTION
The value of interval is a time in seconds, causing vmstat to display statistics at the specified interval. The first report generated
includes statistics for the time since the last reboot. Each subsequent report is for the specified interval only. If you specify count
after interval, it specifies the number of reports generated. For example, vmstat 1 10 produces 10 reports at 1-second intervals. You
cannot specify count without interval, since the first numeric argument to vmstat is always assumed to be interval.
At any time, system memory can be in use by the kernel in kseg, wired (pages that are currently in use and cannot be used for paging), on
the active list (pages that are currently in use but can be used for paging), on the inactive list (pages that are allocated but are most
likely to be used for paging), on the free list (pages that are clean and available for use), or used by the Unified Buffer Cache (UBC).
The vmstat command does not report on the memory in kseg and memory used by the UBC.
The following values are displayed:
Process information: Number of threads that are running or are runnable. Number of threads waiting interruptibly. Number of threads wait-
ing uninterruptibly.
Virtual memory information: Total number of pages on the active list, the inactive list (pages that are allocated but are most likely to be
used for paging), and the Unified Buffer Cache (UBC) least recently used (LRU) list. Total number of pages that are clean and available
for use. Total number of pages that are currently in use and cannot be used for paging (not a real list). Number of address translation
faults that have occurred. Number of copy-on-write page faults, which occur if the requested page is shared by a parent process and one or
more child processes (using the fork function) and if one of the processes needs to modify the page. In this case, VM loads a new address
into the translation buffer and copies the contents of the requested page into the new address for modification by the process. Number of
zero-filled-on-demand page faults, which occur if VM cannot find the page in the internal data structures and if the requested page is new
and has never been referenced. In this case, VM initializes a physical page (the contents of the page are zeroed out) and loads the
address into the page table. Number of pages that have been faulted while on the inactive list. Number of requests for pages from a
pager. Number of pages that have been paged out.
Interrupt information: Number of nonclock device interrupts per second. Number of system calls called per second. Number of task and
thread context switches per second.
CPU information: Percentage of user time for normal and priority processes. Percentage of system time. Percentage of idle time. Percent-
age of iowait. If the -w option is not specified, the iowait time is included in the id statistic.
Specify -f to display fork statistics only. Specify -s for a single display of accumulated statistics, as well as page size.
SEE ALSO
Commands: iostat(1), sysman(8)
vmstat(1)