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28 .\" @(#)vmstat.8 8.1 (Berkeley) 6/6/93
29 .\" $FreeBSD: src/usr.bin/vmstat/vmstat.8,v 1.16.2.5 2001/08/16 13:17:13 ru Exp $
30 .\" $DragonFly: src/usr.bin/vmstat/vmstat.8,v 1.6 2008/09/02 11:50:46 matthias Exp $
37 .Nd report virtual memory statistics
56 reports certain kernel statistics kept about process, virtual memory,
57 disk, trap and cpu activity.
59 The options are as follows:
60 .Bl -tag -width indent
62 Formatted numbers use a brief format which some may find
63 more readable with looped output.
68 The first display is for the time since a reboot and each subsequent
69 report is for the time period since the last display.
74 is specified, the default is infinity, otherwise the default is one.
76 .\" Report on the number
80 .\" system calls since system startup, and the number of pages of virtual memory
83 Report on the number of interrupts taken by each device since system
86 Extract values associated with the name list from the specified
88 instead of the default
91 Extract the name list from the specified
93 instead of the default
96 Report on the usage of kernel dynamic memory listed first by size of
97 allocation and then by type of usage.
99 Change the maximum number of disks to display from the default of 2.
101 Report the usage of kernel object cache.
102 It only works on the running system.
104 Specify which types of devices to display. There are three different
105 categories of devices:
107 .Bl -tag -width indent -compact
109 .Bl -tag -width 9n -compact
111 Direct Access devices
113 Sequential Access devices
119 Write Once Read Multiple devices
125 Optical Memory devices
127 Medium Changer devices
129 Communication devices
131 Storage Array devices
133 Enclosure Services devices
139 .Bl -tag -width 9n -compact
141 Integrated Drive Electronics devices
143 Small Computer System Interface devices
145 Any other device interface
149 .Bl -tag -width 9n -compact
155 The user must specify at least one device type, and may specify at most
156 one device type from each category. Multiple device types in a single
157 device type statement must be separated by commas.
161 arguments may be specified on the command line. All
163 arguments are ORed together to form a matching expression against which
164 all devices in the system are compared. Any device that fully matches
167 argument will be included in the
169 output, up to three devices, or the maximum number of devices specified
172 Display the contents of the
174 structure, giving the total number of several kinds of paging related
175 events which have occurred since system startup.
177 .\" Report on the number of page in and page reclaims since system startup,
178 .\" and the amount of time required by each.
180 Output unformatted numeric values, suitable for field extraction and
182 Columnar output will not be nicely aligned.
184 If specified together with
186 include IRQ numbers and IRQ target CPU numbers before device names.
190 seconds between each display.
193 interval is specified, the default is 1 second.
195 Report on memory used by the kernel zone allocator, by zone.
196 The information shown is the same as that returned by the
203 displays the following information:
204 .Bl -tag -width indent
206 Information about the numbers of processes in various states.
208 .Bl -tag -width indent -compact
212 blocked for resources (i/o, paging, etc.)
214 runnable or short sleeper (< 20 secs) but swapped
217 Information about the usage of virtual and real memory.
218 Virtual pages (reported in units of 1024 bytes) are considered active if
219 they belong to processes which are running or have run in the last 20
222 .Bl -tag -width indent -compact
224 Approximate free and easily-freeable memory.
227 Information about page faults and paging activity.
228 These are averaged each five seconds, and given in units per second.
230 .Bl -tag -width indent -compact
232 total number of page faults
234 page reclaims (simulating reference bits)
236 .\" pages attached (found in free list)
242 pages freed per second
244 .\" anticipated short term memory shortfall
247 Disk operations per second (this field is system dependent).
248 Typically paging will be split across the available drives.
249 The header of the field is the first two characters of the disk name and
251 If more than three disk drives are configured in the system,
253 displays only the first three drives, unless the user specifies the
255 argument to increase the number of drives displayed. This will probably
256 cause the display to exceed 80 columns, however.
259 to display specific drives, their names may be supplied on the command line.
261 defaults to show disks first, and then various other random devices in the
262 system to add up to three devices, if there are that many devices in the
263 system. If devices are specified on the command line, or if a device type
264 matching pattern is specified (see above),
266 will only display the given devices or the devices matching the pattern,
267 and will not randomly select other devices in the system.
269 Trap/interrupt rate averages per second over last 5 seconds.
271 .Bl -tag -width indent -compact
273 device interrupts per interval (including clock interrupts)
275 system calls per interval
277 cpu context switch rate (switches/interval)
280 Breakdown of percentage usage of CPU time.
282 .Bl -tag -width indent -compact
284 user time for normal and low priority processes
292 .Bl -tag -width /dev/kmemxxx -compact
294 default kernel namelist
301 will print what the system is doing every five
302 seconds; this is a good choice of printing interval since this is how often
303 some of the statistics are sampled in the system.
304 Others vary every second and running the output for a while will make it
305 apparent which are recomputed every second.
308 .Dl vmstat -p da -p cd -w 1
309 will tell vmstat to select the first three direct access or CDROM devices
310 and display statistics on those devices, as well as other systems
311 statistics every second.
322 The sections starting with ``Interpreting system activity'' in
323 .%T "Installing and Operating 4.3BSD" .
329 options are only available with the default output.