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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
55 utility reports certain kernel statistics kept about process, virtual memory,
56 disk, trap and cpu activity.
60 option is not specified, information is obtained from
61 the currently running kernel via the
64 Otherwise, information is read from the specified core file,
65 using the name list from the specified kernel image (or from
68 The options are as follows:
69 .Bl -tag -width indent
73 include statistics about interrupts that have never been generated.
78 The first display is for the time since a reboot and each subsequent
79 report is for the time period since the last display.
84 is specified, the default is infinity, otherwise the default is one.
91 system calls since system startup, and the number of pages of virtual memory
94 Changes memory columns into more easily human readable form. Default if
95 standard output is a terminal device.
97 Changes memory columns into straight numbers. Default if standard output
98 is not a terminal device (such as a script).
100 Report on the number of interrupts taken by each device since system
103 Extract values associated with the name list from the specified
109 extract the name list from the specified
111 instead of the default,
112 which is the kernel image the system has booted from.
114 Report on the usage of kernel dynamic memory allocated using
118 Change the maximum number of disks to display from the default of 2.
120 Report per-cpu system/user/idle cpu statistics.
122 Specify which types of devices to display.
123 There are three different
124 categories of devices:
126 .Bl -tag -width indent -compact
128 .Bl -tag -width 9n -compact
130 Direct Access devices
132 Sequential Access devices
138 Write Once Read Multiple devices
144 Optical Memory devices
146 Medium Changer devices
148 Communication devices
150 Storage Array devices
152 Enclosure Services devices
158 .Bl -tag -width 9n -compact
160 Integrated Drive Electronics devices
162 Small Computer System Interface devices
164 Any other device interface
168 .Bl -tag -width 9n -compact
174 The user must specify at least one device type, and may specify at most
175 one device type from each category.
176 Multiple device types in a single
177 device type statement must be separated by commas.
181 arguments may be specified on the command line.
184 arguments are ORed together to form a matching expression against which
185 all devices in the system are compared.
186 Any device that fully matches
189 argument will be included in the
191 output, up to two devices, or the maximum number of devices specified
194 Display the contents of the
196 structure, giving the total number of several kinds of paging related
197 events which have occurred since system startup.
199 .\" Report on the number of page in and page reclaims since system startup,
200 .\" and the amount of time required by each.
204 seconds between each display.
207 interval is specified, the default is 1 second.
210 command will accept and honor a non-integer number of seconds.
212 Report on memory used by the kernel zone allocator,
219 displays the following information:
220 .Bl -tag -width indent
222 Information about the numbers of processes in various states.
224 .Bl -tag -width indent -compact
228 blocked for resources (i/o, paging, etc.)
230 runnable or short sleeper (< 20 secs) but swapped
233 Information about the usage of virtual and real memory.
234 Virtual pages (reported in units of 1024 bytes) are considered active if
235 they belong to processes which are running or have run in the last 20
238 .Bl -tag -width indent -compact
242 size of the free list
245 Information about page faults and paging activity.
246 These are averaged each five seconds, and given in units per second.
248 .Bl -tag -width indent -compact
250 total number of page faults
252 page reclaims (simulating reference bits)
254 .\" pages attached (found in free list)
260 pages freed per second
262 .\" anticipated short term memory shortfall
264 pages scanned by clock algorithm, per-second
267 Disk operations per second (this field is system dependent).
268 Typically paging will be split across the available drives.
269 The header of the field is the first two characters of the disk name and
271 If more than two disk drives are configured in the system,
273 displays only the first two drives, unless the user specifies the
275 argument to increase the number of drives displayed.
277 cause the display to exceed 80 columns, however.
280 to display specific drives, their names may be supplied on the command line.
284 defaults to show disks first, and then various other random devices in the
285 system to add up to two devices, if there are that many devices in the
287 If devices are specified on the command line, or if a device type
288 matching pattern is specified (see above),
290 will only display the given devices or the devices matching the pattern,
291 and will not randomly select other devices in the system.
293 Trap/interrupt rate averages per second over last 5 seconds.
295 .Bl -tag -width indent -compact
297 device interrupts per interval (including clock interrupts)
299 system calls per interval
301 cpu context switch rate (switches/interval)
304 Breakdown of percentage usage of CPU time.
306 .Bl -tag -width indent -compact
308 user time for normal and low priority processes
316 .Bl -tag -width /boot/kernel/kernel -compact
317 .It Pa /boot/kernel/kernel
318 default kernel namelist
325 will print what the system is doing every five
326 seconds; this is a good choice of printing interval since this is how often
327 some of the statistics are sampled in the system.
328 Others vary every second and running the output for a while will make it
329 apparent which are recomputed every second.
332 .Dl vmstat -p da -p cd -w 1
333 will tell vmstat to select the first two direct access or CDROM devices
334 and display statistics on those devices, as well as other systems
335 statistics every second.
350 The sections starting with ``Interpreting system activity'' in
351 .%T "Installing and Operating 4.3BSD" .
357 options are only available with the default output.