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28 .\" @(#)vmstat.8 8.1 (Berkeley) 6/6/93
36 .Nd report virtual memory statistics
41 .Op Fl M Ar core Op Fl N Ar system
56 utility reports certain kernel statistics kept about process, virtual memory,
57 disk, trap and cpu activity.
61 option is not specified, information is obtained from
62 the currently running kernel via the
65 Otherwise, information is read from the specified core file,
66 using the name list from the specified kernel image (or from
69 The options are as follows:
70 .Bl -tag -width indent
74 include statistics about interrupts that have never been generated.
79 The first display is for the time since a reboot and each subsequent
80 report is for the time period since the last display.
85 is specified, the default is infinity, otherwise the default is one.
92 system calls since system startup, and the number of pages of virtual memory
95 Changes memory columns into more easily human readable form.
97 standard output is a terminal device.
99 Changes memory columns into straight numbers.
100 The default if standard output
101 is not a terminal device (such as a script).
103 Report on the number of interrupts taken by each device since system
106 Extract values associated with the name list from the specified
112 extract the name list from the specified
114 instead of the default,
115 which is the kernel image the system has booted from.
117 Report on the usage of kernel dynamic memory allocated using
121 Change the maximum number of disks to display from the default of 2.
123 Display a list of virtual memory objects in the system and the resident
124 memory used by each object.
126 Report per-cpu system/user/idle cpu statistics.
128 Specify which types of devices to display.
129 There are three different
130 categories of devices:
132 .Bl -tag -width indent -compact
134 .Bl -tag -width 9n -compact
136 Direct Access devices
138 Sequential Access devices
144 Write Once Read Multiple devices
150 Optical Memory devices
152 Medium Changer devices
154 Communication devices
156 Storage Array devices
158 Enclosure Services devices
164 .Bl -tag -width 9n -compact
166 Integrated Drive Electronics devices
168 Small Computer System Interface devices
170 Any other device interface
174 .Bl -tag -width 9n -compact
180 The user must specify at least one device type, and may specify at most
181 one device type from each category.
182 Multiple device types in a single
183 device type statement must be separated by commas.
187 arguments may be specified on the command line.
190 arguments are ORed together to form a matching expression against which
191 all devices in the system are compared.
192 Any device that fully matches
195 argument will be included in the
197 output, up to two devices, or the maximum number of devices specified
200 Display the contents of the
202 structure, giving the total number of several kinds of paging related
203 events which have occurred since system startup.
205 .\" Report on the number of page in and page reclaims since system startup,
206 .\" and the amount of time required by each.
210 seconds between each display.
213 interval is specified, the default is 1 second.
216 command will accept and honor a non-integer number of seconds.
218 Report on memory used by the kernel zone allocator,
227 arguments may be given after their respective flags at any point
228 on the command line before the
230 argument(s), or without their flags, as the final argument(s).
231 The latter form is accepted for backwards compatibility, but it is
232 preferred to use the forms with
240 displays the following information:
241 .Bl -tag -width indent
243 Information about the numbers of processes in various states.
245 .Bl -tag -width indent -compact
249 blocked for resources (i/o, paging, etc.)
251 runnable or short sleeper (< 20 secs) but swapped
254 Information about the usage of virtual and real memory.
255 Virtual pages (reported in units of 1024 bytes) are considered active if
256 they belong to processes which are running or have run in the last 20
259 .Bl -tag -width indent -compact
263 size of the free list
266 Information about page faults and paging activity.
267 These are averaged each five seconds, and given in units per second.
269 .Bl -tag -width indent -compact
271 total number of page faults
273 page reclaims (simulating reference bits)
275 .\" pages attached (found in free list)
281 pages freed per second
283 .\" anticipated short term memory shortfall
285 pages scanned by clock algorithm, per-second
288 Disk operations per second (this field is system dependent).
289 Typically paging will be split across the available drives.
290 The header of the field is the first two characters of the disk name and
292 If more than two disk drives are configured in the system,
294 displays only the first two drives, unless the user specifies the
296 argument to increase the number of drives displayed.
298 cause the display to exceed 80 columns, however.
301 to display specific drives, their names may be supplied on the command line.
305 defaults to show disks first, and then various other random devices in the
306 system to add up to two devices, if there are that many devices in the
308 If devices are specified on the command line, or if a device type
309 matching pattern is specified (see above),
311 will only display the given devices or the devices matching the pattern,
312 and will not randomly select other devices in the system.
314 Trap/interrupt rate averages per second over last 5 seconds.
316 .Bl -tag -width indent -compact
318 device interrupts per interval (including clock interrupts)
320 system calls per interval
322 cpu context switch rate (switches/interval)
325 Breakdown of percentage usage of CPU time.
327 .Bl -tag -width indent -compact
329 user time for normal and low priority processes
337 .Bl -tag -width /boot/kernel/kernel -compact
338 .It Pa /boot/kernel/kernel
339 default kernel namelist
346 will print what the system is doing every five
347 seconds; this is a good choice of printing interval since this is how often
348 some of the statistics are sampled in the system.
349 Others vary every second and running the output for a while will make it
350 apparent which are recomputed every second.
353 .Dl vmstat -p da -p cd -w 1
354 will tell vmstat to select the first two direct access or CDROM devices
355 and display statistics on those devices, as well as other systems
356 statistics every second.
371 The sections starting with ``Interpreting system activity'' in
372 .%T "Installing and Operating 4.3BSD" .
378 options are only available with the default output.