Options¶

The -a switch displays active/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.

The -t switch adds timestamp to the output.

The -m switch displays slabinfo.

The -n switch causes the header to be displayed only once rather than periodically.

The -s switch displays a table of various event counters and memory statistics. This display does not repeat.

delay is the delay between updates in seconds. If no delay is specified, only one report is printed with the average values since boot.

count is the number of updates. If no count is specified and delay is defined, count defaults to infinity.

The -d reports disk statistics (2.5.70 or above required)

The -w enlarges field width for big memory sizes

The -p followed by some partition name for detailed statistics (2.5.70 or above required)

The -S followed by k or K or m or M switches outputs between 1000, 1024, 1000000, or 1048576 bytes

The -V switch results in displaying version information.

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.

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