RES shows how much memory associated with the process is currently resident, regardless of what type of memory that is. The size of any shared memory segment that may be shared with other processes, as well as regular chunks of private memoryĪllocated by the process, some of which may be swapped out. In this view, VIRT represents the size of the memory address space allocated by the process, which includes the size of any memory mapped file, Tasks: 225 total, 1 running, 224 sleeping, 0 stopped, 0 zombie Running “top” for instance, usually shows this kind of output: One service is created on each host that provides the section creates a service instead.Shared memory, swapping and memory-mapped files all make it difficult to accurately assess how much memory a process is actually Hint: If you want to monitor swapping, you probably better measure major pagefaults. That means that this check gets critical if the memory used by processes is twice the size of your RAM. So when defining a level to check against, the only value that is not affected by such internals of memory management is the total amount of virtual memory used up by processes (not by disk buffers).Ĭheckmk lets you define levels in percentage of the physically installed RAM or as absolute values in MB.
That is because Linux has taken RAM from processes in order to increase disk buffers. It does this in situations where disk buffers (are assumed to) speed up the overall performance more than keeping rarely used parts of processes in RAM.įor example after a complete backup of your system you might experiance that your swap usage has increased while you have more RAM free then before. Linux tends to swap out parts of processes even if RAM is available. In fact it is the only way to do it right (at least for Linux): What parts of a process currently reside in physical RAM and what parts are swapped out is not related in a direct way with the current memory usage. You can define a warningĪnd critical level for the usage of virtual memory, This check measures the current usage of physical RAM and Check manual page of mem_used Usage of Physical and Virtual RAM
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