title: Usage of Vmalloc Address Space
agents: linux
catalog: os/kernel
license: GPLv2
distribution: check_mk
description:
 The linux kernel keeps a part of the available address
 space free for usage by device drivers, e.g. for address
 mappings of IO devices into the physical address space.
 An example is the graphics driver used by the X server,
 which needs address mappings for communicating with
 the hardware. In {/proc/meminfo} that area is called
 {VmallocTotal}. On 32 bit architectures this area has
 a very limited size and is subject to fragmentation or
 consumption by buggy graphics drivers.

 This check monitors the current usage of the the vmalloc
 address space and also the size of the largest available
 chunk (indicating the degree of fragmentation).

discovery:
 One service is created if {VmallocTotal} is available in {/proc/meminfo}
 and only if the total size of the vmalloc area is less then 4 GB.
 This is generally only possible for 32 bit architectures.