1VMSTAT(8) Linux Administrator's Manual VMSTAT(8)
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6 vmstat - Report virtual memory statistics
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9 vmstat [-a] [-n] [-t] [delay [ count]]
10 vmstat [-f] [-s] [-m]
11 vmstat [-S unit]
12 vmstat [-d]
13 vmstat [-p disk partition]
14 vmstat [-V]
15
17 vmstat reports information about processes, memory, paging, block IO,
18 traps, and cpu activity.
19 The first report produced gives averages since the last reboot. Addi‐
21 tional reports give information on a sampling period of length delay.
22 The process and memory reports are instantaneous in either case.
23 Options
26 The -a switch displays active/inactive memory, given a 2.5.41 kernel or
27 better.
28 The -f switch displays the number of forks since boot. This includes
30 the fork, vfork, and clone system calls, and is equivalent to the total
31 number of tasks created. Each process is represented by one or more
32 tasks, depending on thread usage. This display does not repeat.
33 The -t switch adds timestamp to the output.
35 The -m switch displays slabinfo.
37 The -n switch causes the header to be displayed only once rather than
39 periodically.
40 The -s switch displays a table of various event counters and memory
42 statistics. This display does not repeat.
43 delay is the delay between updates in seconds. If no delay is speci‐
45 fied, only one report is printed with the average values since boot.
46 count is the number of updates. If no count is specified and delay is
48 defined, count defaults to infinity.
49 The -d reports disk statistics (2.5.70 or above required)
51 The -p followed by some partition name for detailed statistics (2.5.70
53 or above required)
54 The -S followed by k or K or m or M switches outputs between 1000,
56 1024, 1000000, or 1048576 bytes
57 The -V switch results in displaying version information.
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61 Procs
62 r: The number of processes waiting for run time.
63 b: The number of processes in uninterruptible sleep.
64 Memory
66 swpd: the amount of virtual memory used.
67 free: the amount of idle memory.
68 buff: the amount of memory used as buffers.
69 cache: the amount of memory used as cache.
70 inact: the amount of inactive memory. (-a option)
71 active: the amount of active memory. (-a option)
72 Swap
74 si: Amount of memory swapped in from disk (/s).
75 so: Amount of memory swapped to disk (/s).
76 IO
78 bi: Blocks received from a block device (blocks/s).
79 bo: Blocks sent to a block device (blocks/s).
80 System
82 in: The number of interrupts per second, including the clock.
83 cs: The number of context switches per second.
84 CPU
86 These are percentages of total CPU time.
87 us: Time spent running non-kernel code. (user time, including nice time)
88 sy: Time spent running kernel code. (system time)
89 id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
90 wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
91 st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.
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95 Reads
96 total: Total reads completed successfully
97 merged: grouped reads (resulting in one I/O)
98 sectors: Sectors read successfully
99 ms: milliseconds spent reading
100 Writes
102 total: Total writes completed successfully
103 merged: grouped writes (resulting in one I/O)
104 sectors: Sectors written successfully
105 ms: milliseconds spent writing
106 IO
108 cur: I/O in progress
109 s: seconds spent for I/O
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113 reads: Total number of reads issued to this partition
114 read sectors: Total read sectors for partition
115 writes : Total number of writes issued to this partition
116 requested writes: Total number of write requests made for partition
117
121 cache: Cache name
122 num: Number of currently active objects
123 total: Total number of available objects
124 size: Size of each object
125 pages: Number of pages with at least one active object
126 totpages: Total number of allocated pages
127 pslab: Number of pages per slab
128
131 vmstat does not require special permissions.
132 These reports are intended to help identify system bottlenecks. Linux
134 vmstat does not count itself as a running process.
135 All linux blocks are currently 1024 bytes. Old kernels may report
137 blocks as 512 bytes, 2048 bytes, or 4096 bytes.
138 Since procps 3.1.9, vmstat lets you choose units (k, K, m, M) default
140 is K (1024 bytes) in the default mode
141 vmstat uses slabinfo 1.1 FIXME
143
145 /proc/meminfo
146 /proc/stat
147 /proc/*/stat
148
151 iostat(1), sar(1), mpstat(1), ps(1), top(1), free(1)
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154 Does not tabulate the block io per device or count the number of system
155 calls.
156
158 Written by Henry Ware <al172@yfn.ysu.edu>.
159 Fabian Frédérick <ffrederick@users.sourceforge.net> (diskstat, slab, partitions...)
160Throatwobbler Ginkgo Labs 27 July 1994 VMSTAT(8)