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
32              includes 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 swap (si/so)
59              or block (bi/bo) fields.
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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 in uninterruptible sleep.
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80   Memory
81       swpd: the amount of virtual memory used.
82       free: the amount of idle memory.
83       buff: the amount of memory used as buffers.
84       cache: the amount of memory used as cache.
85       inact: the amount of inactive memory.  (-a option)
86       active: the amount of active memory.  (-a option)
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88   Swap
89       si: Amount of memory swapped in from disk (/s).
90       so: Amount of memory swapped to disk (/s).
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92   IO
93       bi: Blocks received from a block device (blocks/s).
94       bo: Blocks sent to a block device (blocks/s).
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96   System
97       in: The number of interrupts per second, including the clock.
98       cs: The number of context switches per second.
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100   CPU
101       These are percentages of total CPU time.
102       us: Time spent running non-kernel code.  (user time, including nice time)
103       sy: Time spent running kernel code.  (system time)
104       id: Time spent idle.  Prior to Linux 2.5.41, this includes IO-wait time.
105       wa: Time spent waiting for IO.  Prior to Linux 2.5.41, included in idle.
106       st: Time stolen from a virtual machine.  Prior to Linux 2.6.11, unknown.
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FIELD DESCRIPTION FOR DISK MODE

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

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

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

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

153       /proc/meminfo
154       /proc/stat
155       /proc/*/stat
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SEE ALSO

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

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

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

170       Please send bug reports to ⟨procps@freelists.org⟩
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174procps-ng                       September 2011                       VMSTAT(8)
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