1VMSTAT(8) System Administration VMSTAT(8)
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6 vmstat - Report virtual memory statistics
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9 vmstat [options] [delay [count]]
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12 vmstat reports information about processes, memory, paging, block IO,
13 traps, disks and cpu activity.
14 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.
18
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.
22 count Number of updates. In absence of count, when delay is defined,
24 default is infinite.
25 -a, --active
27 Display active and inactive memory, given a 2.5.41 kernel or
28 better.
29 -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.
36 -m, --slabs
38 Displays slabinfo.
39 -n, --one-header
41 Display the header only once rather than periodically.
42 -s, --stats
44 Displays a table of various event counters and memory statis‐
45 tics. This display does not repeat.
46 -d, --disk
48 Report disk statistics (2.5.70 or above required).
49 -D, --disk-sum
51 Report some summary statistics about disk activity.
52 -p, --partition device
54 Detailed statistics about partition (2.5.70 or above required).
55 -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.
60 -t, --timestamp
62 Append timestamp to each line
63 -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.
68 -y, --no-first
70 Omits first report with statistics since system boot.
71 -V, --version
73 Display version information and exit.
74 -h, --help
76 Display help and exit.
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79 Procs
80 r: The number of runnable processes (running or waiting for run time).
81 b: The number of processes blocked waiting for I/O to complete.
82 Memory
84 These are affected by the --unit option.
85 swpd: the amount of swap memory used.
86 free: the amount of idle memory.
87 buff: the amount of memory used as buffers.
88 cache: the amount of memory used as cache.
89 inact: the amount of inactive memory. (-a option)
90 active: the amount of active memory. (-a option)
91 Swap
93 These are affected by the --unit option.
94 si: Amount of memory swapped in from disk (/s).
95 so: Amount of memory swapped to disk (/s).
96 IO
98 bi: Kibibyte received from a block device (KiB/s).
99 bo: Kibibyte sent to a block device (KiB/s).
100 System
102 in: The number of interrupts per second, including the clock.
103 cs: The number of context switches per second.
104 CPU
106 These are percentages of total CPU time.
107 us: Time spent running non-kernel code. (user time, including nice time)
108 sy: Time spent running kernel code. (system time)
109 id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
110 wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
111 st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.
112 gu: Time spent running KVM guest code (guest time, including guest nice).
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115 Reads
116 total: Total reads completed successfully
117 merged: grouped reads (resulting in one I/O)
118 sectors: Sectors read successfully
119 ms: milliseconds spent reading
120 Writes
122 total: Total writes completed successfully
123 merged: grouped writes (resulting in one I/O)
124 sectors: Sectors written successfully
125 ms: milliseconds spent writing
126 IO
128 cur: I/O in progress
129 s: seconds spent for I/O
130
132 reads: Total number of reads issued to this partition
133 read sectors: Total read sectors for partition
134 writes : Total number of writes issued to this partition
135 requested writes: Total number of write requests made for partition
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138 Slab mode shows statistics per slab, for more information about this
139 information see slabinfo(5)
140 cache: Cache name
142 num: Number of currently active objects
143 total: Total number of available objects
144 size: Size of each object
145 pages: Number of pages with at least one active object
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148 vmstat requires read access to files under /proc. The -m requires read
149 access to /proc/slabinfo which may not be available to standard users.
150 Mount options for /proc such as subset=pid may also impact what is vis‐
151 ible.
152
154 free(1), iostat(1), mpstat(1), ps(1), sar(1), top(1), slabinfo(5)
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157 Please send bug reports to ⟨procps@freelists.org⟩
158procps-ng 2023-01-18 VMSTAT(8)