vmstat
Report virtual memory statistics
see also :
free - ps - top
Synopsis
vmstat
[options] [delay [count]]
add an example, a script, a trick and tips
examples
no example yet ...
... Feel free to add your own example above to help other Linux-lovers !
description
vmstat
reports information about processes, memory, paging, block
IO, traps, disks and cpu activity.
The first
report produced gives averages since the last reboot.
Additional reports give information on a sampling period of
length delay. The process and memory reports are
instantaneous in either case.
options
delay
The delay between updates
in seconds. If no delay is specified, only one report
is printed with the average values since boot.
count
Number of updates. In absence of count, when
delay is defined, default is infinite.
-a,
--active
Display active and inactive
memory, given a 2.5.41 kernel or better.
-f,
--forks
The -f switch
displays the number of forks since boot. This includes the
fork, vfork, and clone system calls, and is equivalent to
the total number of tasks created. Each process is
represented by one or more tasks, depending on thread usage.
This display does not repeat.
-m,
--slabs
Displays slabinfo.
-n,
--one-header
Display the header only once
rather than periodically.
-s,
--stats
Displays a table of various
event counters and memory statistics. This display does not
repeat.
-d,
--disk
Report disk statistics (2.5.70
or above required).
-D,
--disk-sum
Report some summary statistics
about disk activity.
-p,
--partition device
Detailed statistics about
partition (2.5.70 or above required).
-S,
--unit character
Switches outputs between 1000
(k), 1024 (K), 1000000 (m), or 1048576
(M) bytes. Note this does not change the swap (si/so)
or block (bi/bo) fields.
-V,
--version
Display version information and
exit.
-h,
--help
Display help and exit.
field description for disk mode
Reads
total: Total reads completed successfully
merged: grouped reads (resulting in one I/O)
sectors: Sectors read successfully
ms: milliseconds spent reading
Writes
total: Total writes completed successfully
merged: grouped writes (resulting in one I/O)
sectors: Sectors written successfully
ms: milliseconds spent writing
IO
cur: I/O in progress
s: seconds spent for I/O
field description for disk partition mode
reads: Total number of reads issued to this partition
read sectors: Total read sectors for partition
writes : Total number of writes issued to this partition
requested writes: Total number of write requests made for
partition
field description for slab mode
cache: Cache name
num: Number of currently active objects
total: Total number of available objects
size: Size of each object
pages: Number of pages with at least one active object
field description for vm mode
Procs
r: The number of processes waiting for run time.
b: The number of processes in uninterruptible sleep.
Memory
swpd: the amount of virtual memory used.
free: the amount of idle memory.
buff: the amount of memory used as buffers.
cache: the amount of memory used as cache.
inact: the amount of inactive memory. (-a option)
active: the amount of active memory. (-a option)
Swap
si: Amount of memory swapped in from disk (/s).
so: Amount of memory swapped to disk (/s).
IO
bi: Blocks received from a block device (blocks/s).
bo: Blocks sent to a block device (blocks/s).
System
in: The number of interrupts per second, including the clock.
cs: The number of context switches per second.
CPU
These are percentages of total CPU time.
us: Time spent running non-kernel code. (user time, including
nice time)
sy: Time spent running kernel code. (system time)
id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait
time.
wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in
idle.
st: Time stolen from a virtual machine. Prior to Linux 2.6.11,
unknown.
files
/proc/meminfo
/proc/stat
/proc/*/stat
notes
vmstat does not require special permissions.
These reports are intended to help identify system bottlenecks.
Linux vmstat does not count itself as a running process.
All linux blocks are currently 1024 bytes. Old kernels may report
blocks as 512 bytes, 2048 bytes, or 4096 bytes.
Since procps 3.1.9, vmstat lets you choose units (k, K, m, M).
Default is K (1024 bytes) in the default mode.
vmstat uses slabinfo 1.1
reporting bugs
Please send bug reports to procps[:at:]freelists[:dot:]org
(procps[:at:]freelists[:dot:]org)
bugs
Does not
tabulate the block io per device or count the number of
system calls.
see also
free ,
iostat, mpstat, ps ,
sar, top
authors
Written by
Henry Ware (al172[:at:]yfn.ysu[:dot:]edu).
Fabian
Frédérick (ffrederick[:at:]users.sourceforge[:dot:]net) (diskstat, slab,
partitions...)