1VMSTAT(8)                    System Administration                   VMSTAT(8)
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NAME

6       vmstat - Report virtual memory statistics
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SYNOPSIS

9       vmstat [options] [delay [count]]
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DESCRIPTION

12       vmstat  reports  information about processes, memory, paging, block IO,
13       traps, disks and cpu activity.
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15       The first report produced gives averages since the last reboot.   Addi‐
16       tional  reports  give information on a sampling period of length delay.
17       The process and memory reports are instantaneous in either case.
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OPTIONS

20       delay  The delay between updates in seconds.  If no delay is specified,
21              only one report is printed with the average values since boot.
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23       count  Number  of updates.  In absence of count, when delay is defined,
24              default is infinite.
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26       -a, --active
27              Display active and  inactive memory, given a  2.5.41  kernel  or
28              better.
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30       -f, --forks
31              The -f switch displays the number of forks since boot.  This in‐
32              cludes the fork, vfork, and clone system calls, and  is  equiva‐
33              lent to the total number of tasks created.  Each process is rep‐
34              resented by one or more tasks, depending on thread usage.   This
35              display does not repeat.
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37       -m, --slabs
38              Displays slabinfo.
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40       -n, --one-header
41              Display the header only once rather than periodically.
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43       -s, --stats
44              Displays  a  table  of various event counters and memory statis‐
45              tics.  This display does not repeat.
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47       -d, --disk
48              Report disk statistics (2.5.70 or above required).
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50       -D, --disk-sum
51              Report some summary statistics about disk activity.
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53       -p, --partition device
54              Detailed statistics about partition (2.5.70 or above required).
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56       -S, --unit character
57              Switches outputs between 1000 (k), 1024  (K),  1000000  (m),  or
58              1048576  (M) bytes.  Note this does not change the block (bi/bo)
59              fields, which are always measured in blocks.
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61       -t, --timestamp
62              Append timestamp to each line
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64       -w, --wide
65              Wide output mode (useful for systems with higher amount of  mem‐
66              ory,  where the default output mode suffers from unwanted column
67              breakage).  The output is wider than 80 characters per line.
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69       -V, --version
70              Display version information and exit.
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72       -h, --help
73              Display help and exit.
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FIELD DESCRIPTION FOR VM MODE

76   Procs
77       r: The number of runnable processes (running or waiting for run time).
78       b: The number of processes blocked waiting for I/O to complete.
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80   Memory
81       These are affected by the --unit option.
82       swpd: the amount of swap memory used.
83       free: the amount of idle memory.
84       buff: the amount of memory used as buffers.
85       cache: the amount of memory used as cache.
86       inact: the amount of inactive memory.  (-a option)
87       active: the amount of active memory.  (-a option)
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89   Swap
90       These are affected by the --unit option.
91       si: Amount of memory swapped in from disk (/s).
92       so: Amount of memory swapped to disk (/s).
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94   IO
95       bi: Blocks received from a block device (blocks/s).
96       bo: Blocks sent to a block device (blocks/s).
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98   System
99       in: The number of interrupts per second, including the clock.
100       cs: The number of context switches per second.
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102   CPU
103       These are percentages of total CPU time.
104       us: Time spent running non-kernel code.  (user time, including nice time)
105       sy: Time spent running kernel code.  (system time)
106       id: Time spent idle.  Prior to Linux 2.5.41, this includes IO-wait time.
107       wa: Time spent waiting for IO.  Prior to Linux 2.5.41, included in idle.
108       st: Time stolen from a virtual machine.  Prior to Linux 2.6.11, unknown.
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FIELD DESCRIPTION FOR DISK MODE

111   Reads
112       total: Total reads completed successfully
113       merged: grouped reads (resulting in one I/O)
114       sectors: Sectors read successfully
115       ms: milliseconds spent reading
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117   Writes
118       total: Total writes completed successfully
119       merged: grouped writes (resulting in one I/O)
120       sectors: Sectors written successfully
121       ms: milliseconds spent writing
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123   IO
124       cur: I/O in progress
125       s: seconds spent for I/O
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FIELD DESCRIPTION FOR DISK PARTITION MODE

128       reads: Total number of reads issued to this partition
129       read sectors: Total read sectors for partition
130       writes : Total number of writes issued to this partition
131       requested writes: Total number of write requests made for partition
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FIELD DESCRIPTION FOR SLAB MODE

134       cache: Cache name
135       num: Number of currently active objects
136       total: Total number of available objects
137       size: Size of each object
138       pages: Number of pages with at least one active object
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NOTES

141       vmstat does not require special permissions.
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143       These reports are intended to help identify system bottlenecks.   Linux
144       vmstat does not count itself as a running process.
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146       All  linux  blocks  are  currently  1024 bytes.  Old kernels may report
147       blocks as 512 bytes, 2048 bytes, or 4096 bytes.
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149       Since procps 3.1.9, vmstat lets you choose units (k, K, m, M).  Default
150       is K (1024 bytes) in the default mode.
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152       vmstat uses slabinfo 1.1
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FILES

155       /proc/meminfo
156       /proc/stat
157       /proc/*/stat
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SEE ALSO

160       free(1), iostat(1), mpstat(1), ps(1), sar(1), top(1)
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BUGS

163       Does not tabulate the block io per device or count the number of system
164       calls.
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AUTHORS

167       Written by Henry Ware ⟨al172@yfn.ysu.edu⟩.
168       Fabian Frédérick  ⟨ffrederick@users.sourceforge.net⟩  (diskstat,  slab,
169       partitions...)
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REPORTING BUGS

172       Please send bug reports to ⟨procps@freelists.org⟩
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176procps-ng                         2020-06-04                         VMSTAT(8)
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