Check manual page of mem.vmalloc

mem.vmalloc

Author: Mathias Kettner

License: GPL

Distribution: official part of Check_MK

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).

Check parameters

Parameter	Type	Description
warn_used	int or float	the amount of used vmalloc space triggering a warning. If the level is specified as an integer, it is interpreted as an absolute value in MB. Float values are interpreted as percentages of the total vmalloc area.
crit_used	int or float	used amount that triggers a critical state.
warn_chunk	int or float	if the size of the largest chunk reaches that value or is below, a warning is triggered. The value is in MB (int) or percentage of the total vmalloc area (float)
crit_chunk	int or float	critical level for the size of the largest available chunk.

Performance data

Two variables: the current usage in MB and the size of the largest chunk in MB.

Inventory

A check 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.

Please add mem.vmalloc to ignored_checktypes if you do not need this check.

Configuration variables

Variable	Type	Description
mem_vmalloc_default_levels	int/float, int/float, int/float, int/float	Levels used by checks created by inventory. The default value is set to (80.0, 90.0, 64, 32).

Examples

# set warn/used for used size to 100 MB and 120 MB.
# set levels for largest chunk to 50% / 30% of total
# vmalloc size
mem_vmalloc_default_levels = (100, 120, 50.0, 30.0)