Check manual page of mem_vmalloc

Usage of Vmalloc Address Space

Distribution	Official part of Checkmk
License	GPLv2
Supported Agents	Linux

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.