Report virtual memory statistics
see also :
free - ps - top
[options] [delay [count]]
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reports information about processes, memory, paging, block
IO, traps, disks and cpu activity.
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.
The delay between updates
in seconds. If no delay is specified, only one report
is printed with the average values since boot.
Number of updates. In absence of count, when
delay is defined, default is infinite.
Display active and inactive
memory, given a 2.5.41 kernel or better.
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.
Display the header only once
rather than periodically.
Displays a table of various
event counters and memory statistics. This display does not
Report disk statistics (2.5.70
or above required).
Report some summary statistics
about disk activity.
Detailed statistics about
partition (2.5.70 or above required).
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.
Display version information and
Display help and exit.
field description for disk mode
total: Total reads completed successfully
merged: grouped reads (resulting in one I/O)
sectors: Sectors read successfully
ms: milliseconds spent reading
total: Total writes completed successfully
merged: grouped writes (resulting in one I/O)
sectors: Sectors written successfully
ms: milliseconds spent writing
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
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
r: The number of processes waiting for run time.
b: The number of processes in uninterruptible sleep.
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)
si: Amount of memory swapped in from disk (/s).
so: Amount of memory swapped to disk (/s).
bi: Blocks received from a block device (blocks/s).
bo: Blocks sent to a block device (blocks/s).
in: The number of interrupts per second, including the clock.
cs: The number of context switches per second.
These are percentages of total CPU time.
us: Time spent running non-kernel code. (user time, including
sy: Time spent running kernel code. (system time)
id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait
wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in
st: Time stolen from a virtual machine. Prior to Linux 2.6.11,
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
Please send bug reports to procps[:at:]freelists[:dot:]org
tabulate the block io per device or count the number of
iostat, mpstat, ps ,
Henry Ware (al172[:at:]yfn.ysu[:dot:]edu).
Frédérick (ffrederick[:at:]users.sourceforge[:dot:]net) (diskstat, slab,