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28 .\" @(#)vmstat.8 8.1 (Berkeley) 6/6/93
36 .Nd report virtual memory statistics
42 .Op Fl M Ar core Op Fl N Ar system
57 utility reports certain kernel statistics kept about process, virtual memory,
58 disk, trap and cpu activity.
62 option is not specified, information is obtained from
63 the currently running kernel via the
66 Otherwise, information is read from the specified core file,
67 using the name list from the specified kernel image (or from
70 The options are as follows:
71 .Bl -tag -width indent
75 in a selection of different human and machine readable formats.
78 for details on command line arguments.
82 include statistics about interrupts that have never been generated.
87 The first display is for the time since a reboot and each subsequent
88 report is for the time period since the last display.
93 is specified, the default is infinity, otherwise the default is one.
100 system calls since system startup, and the number of pages of virtual memory
103 Changes memory columns into more easily human readable form.
105 standard output is a terminal device.
107 Changes memory columns into straight numbers.
108 The default if standard output
109 is not a terminal device (such as a script).
111 Report on the number of interrupts taken by each device since system
114 Extract values associated with the name list from the specified
120 extract the name list from the specified
122 instead of the default,
123 which is the kernel image the system has booted from.
125 Report on the usage of kernel dynamic memory allocated using
129 Change the maximum number of disks to display from the default of 2.
131 Display a list of virtual memory objects in the system and the resident
132 memory used by each object.
134 Report per-cpu system/user/idle cpu statistics.
136 Specify which types of devices to display.
137 There are three different
138 categories of devices:
140 .Bl -tag -width indent -compact
142 .Bl -tag -width 9n -compact
144 Direct Access devices
146 Sequential Access devices
152 Write Once Read Multiple devices
158 Optical Memory devices
160 Medium Changer devices
162 Communication devices
164 Storage Array devices
166 Enclosure Services devices
172 .Bl -tag -width 9n -compact
174 Integrated Drive Electronics devices
176 Small Computer System Interface devices
178 Any other device interface
182 .Bl -tag -width 9n -compact
188 The user must specify at least one device type, and may specify at most
189 one device type from each category.
190 Multiple device types in a single
191 device type statement must be separated by commas.
195 arguments may be specified on the command line.
198 arguments are ORed together to form a matching expression against which
199 all devices in the system are compared.
200 Any device that fully matches
203 argument will be included in the
205 output, up to two devices, or the maximum number of devices specified
208 Display the contents of the
210 structure, giving the total number of several kinds of paging related
211 events which have occurred since system startup.
213 .\" Report on the number of page in and page reclaims since system startup,
214 .\" and the amount of time required by each.
218 seconds between each display.
221 interval is specified, the default is 1 second.
224 command will accept and honor a non-integer number of seconds.
226 Report on memory used by the kernel zone allocator,
235 arguments may be given after their respective flags at any point
236 on the command line before the
238 argument(s), or without their flags, as the final argument(s).
239 The latter form is accepted for backwards compatibility, but it is
240 preferred to use the forms with
248 displays the following information:
249 .Bl -tag -width indent
251 Information about the numbers of processes in various states.
253 .Bl -tag -width indent -compact
257 blocked for resources (i/o, paging, etc.)
259 runnable or short sleeper (< 20 secs) but swapped
262 Information about the usage of virtual and real memory.
263 Virtual pages (reported in units of 1024 bytes) are considered active if
264 they belong to processes which are running or have run in the last 20
267 .Bl -tag -width indent -compact
271 size of the free list
274 Information about page faults and paging activity.
275 These are averaged each five seconds, and given in units per second.
277 .Bl -tag -width indent -compact
279 total number of page faults
281 page reclaims (simulating reference bits)
283 .\" pages attached (found in free list)
289 pages freed per second
291 .\" anticipated short term memory shortfall
293 pages scanned by clock algorithm, per-second
296 Disk operations per second (this field is system dependent).
297 Typically paging will be split across the available drives.
298 The header of the field is the first two characters of the disk name and
300 If more than two disk drives are configured in the system,
302 displays only the first two drives, unless the user specifies the
304 argument to increase the number of drives displayed.
306 cause the display to exceed 80 columns, however.
309 to display specific drives, their names may be supplied on the command line.
313 defaults to show disks first, and then various other random devices in the
314 system to add up to two devices, if there are that many devices in the
316 If devices are specified on the command line, or if a device type
317 matching pattern is specified (see above),
319 will only display the given devices or the devices matching the pattern,
320 and will not randomly select other devices in the system.
322 Trap/interrupt rate averages per second over last 5 seconds.
324 .Bl -tag -width indent -compact
326 device interrupts per interval (including clock interrupts)
328 system calls per interval
330 cpu context switch rate (switches/interval)
333 Breakdown of percentage usage of CPU time.
335 .Bl -tag -width indent -compact
337 user time for normal and low priority processes
345 .Bl -tag -width /boot/kernel/kernel -compact
346 .It Pa /boot/kernel/kernel
347 default kernel namelist
354 will print what the system is doing every five
355 seconds; this is a good choice of printing interval since this is how often
356 some of the statistics are sampled in the system.
357 Others vary every second and running the output for a while will make it
358 apparent which are recomputed every second.
361 .Dl vmstat -p da -p cd -w 1
362 will tell vmstat to select the first two direct access or CDROM devices
363 and display statistics on those devices, as well as other systems
364 statistics every second.
373 .Xr xo_parse_args 3 ,
381 The sections starting with ``Interpreting system activity'' in
382 .%T "Installing and Operating 4.3BSD" .
388 options are only available with the default output.