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32 .\" @(#)vmstat.8 8.1 (Berkeley) 6/6/93
40 .Nd report virtual memory statistics
46 .Op Fl M Ar core Op Fl N Ar system
59 utility reports certain kernel statistics kept about process, virtual memory,
60 disk, trap and cpu activity.
64 option is not specified, information is obtained from
65 the currently running kernel via the
68 Otherwise, information is read from the specified core file,
69 using the name list from the specified kernel image (or from
72 The options are as follows:
73 .Bl -tag -width indent
77 include statistics about interrupts that have never been generated.
82 The first display is for the time since a reboot and each subsequent
83 report is for the time period since the last display.
88 is specified, the default is infinity, otherwise the default is one.
95 system calls since system startup, and the number of pages of virtual memory
98 Report on the number of interrupts taken by each device since system
101 Extract values associated with the name list from the specified
107 extract the name list from the specified
109 instead of the default,
110 which is the kernel image the system has booted from.
112 Report on the usage of kernel dynamic memory listed first by size of
113 allocation and then by type of usage.
115 Change the maximum number of disks to display from the default of 2.
117 Specify which types of devices to display.
118 There are three different
119 categories of devices:
121 .Bl -tag -width indent -compact
123 .Bl -tag -width 9n -compact
125 Direct Access devices
127 Sequential Access devices
133 Write Once Read Multiple devices
139 Optical Memory devices
141 Medium Changer devices
143 Communication devices
145 Storage Array devices
147 Enclosure Services devices
153 .Bl -tag -width 9n -compact
155 Integrated Drive Electronics devices
157 Small Computer System Interface devices
159 Any other device interface
163 .Bl -tag -width 9n -compact
169 The user must specify at least one device type, and may specify at most
170 one device type from each category.
171 Multiple device types in a single
172 device type statement must be separated by commas.
176 arguments may be specified on the command line.
179 arguments are ORed together to form a matching expression against which
180 all devices in the system are compared.
181 Any device that fully matches
184 argument will be included in the
186 output, up to two devices, or the maximum number of devices specified
189 Display the contents of the
191 structure, giving the total number of several kinds of paging related
192 events which have occurred since system startup.
194 .\" Report on the number of page in and page reclaims since system startup,
195 .\" and the amount of time required by each.
199 seconds between each display.
202 interval is specified, the default is 1 second.
204 Report on memory used by the kernel zone allocator, by zone.
205 The information shown is the same as that returned by the
212 displays the following information:
214 .Bl -tag -width indent
216 Information about the numbers of processes in various states.
218 .Bl -tag -width indent -compact
222 blocked for resources (i/o, paging, etc.)
224 runnable or short sleeper (< 20 secs) but swapped
227 Information about the usage of virtual and real memory.
228 Virtual pages (reported in units of 1024 bytes) are considered active if
229 they belong to processes which are running or have run in the last 20
232 .Bl -tag -width indent -compact
236 size of the free list
239 Information about page faults and paging activity.
240 These are averaged each five seconds, and given in units per second.
242 .Bl -tag -width indent -compact
244 total number of page faults
246 page reclaims (simulating reference bits)
248 .\" pages attached (found in free list)
254 pages freed per second
256 .\" anticipated short term memory shortfall
258 pages scanned by clock algorithm, per-second
261 Disk operations per second (this field is system dependent).
262 Typically paging will be split across the available drives.
263 The header of the field is the first two characters of the disk name and
265 If more than two disk drives are configured in the system,
267 displays only the first two drives, unless the user specifies the
269 argument to increase the number of drives displayed.
271 cause the display to exceed 80 columns, however.
274 to display specific drives, their names may be supplied on the command line.
278 defaults to show disks first, and then various other random devices in the
279 system to add up to two devices, if there are that many devices in the
281 If devices are specified on the command line, or if a device type
282 matching pattern is specified (see above),
284 will only display the given devices or the devices matching the pattern,
285 and will not randomly select other devices in the system.
287 Trap/interrupt rate averages per second over last 5 seconds.
289 .Bl -tag -width indent -compact
291 device interrupts per interval (including clock interrupts)
293 system calls per interval
295 cpu context switch rate (switches/interval)
298 Breakdown of percentage usage of CPU time.
300 .Bl -tag -width indent -compact
302 user time for normal and low priority processes
310 .Bl -tag -width /boot/kernel/kernel -compact
311 .It Pa /boot/kernel/kernel
312 default kernel namelist
319 will print what the system is doing every five
320 seconds; this is a good choice of printing interval since this is how often
321 some of the statistics are sampled in the system.
322 Others vary every second and running the output for a while will make it
323 apparent which are recomputed every second.
326 .Dl vmstat -p da -p cd -w 1
327 will tell vmstat to select the first two direct access or CDROM devices
328 and display statistics on those devices, as well as other systems
329 statistics every second.
341 The sections starting with ``Interpreting system activity'' in
342 .%T "Installing and Operating 4.3BSD" .
348 options are only available with the default output.