For the resource consumption on system level, pcp-atop uses
colors to indicate that a critical occupation percentage has been
(almost) reached. A critical occupation percentage means that is
likely that this load causes a noticeable negative performance
influence for applications using this resource. The critical
percentage depends on the type of resource: e.g. the performance
influence of a disk with a busy percentage of 80% might be more
noticeable for applications/user than a CPU with a busy
percentage of 90%.
Currently pcp-atop uses the following default values to calculate
a weighted percentage per resource:
Processor
A busy percentage of 90% or higher is considered `critical'.
Disk
A busy percentage of 70% or higher is considered `critical'.
Network
A busy percentage of 90% or higher for the load of an
interface is considered `critical'.
Memory
An occupation percentage of 90% is considered `critical'.
Notice that this occupation percentage is the accumulated
memory consumption of the kernel (including slab) and all
processes; the memory for the page cache (`cache' and `buff'
in the MEM-line) and the reclaimable part of the slab
(`slrec`) is not implied!
If the number of pages swapped out (`swout' in the PAG-line)
is larger than 10 per second, the memory resource is
considered `critical'. A value of at least 1 per second is
considered `almost critical'.
If the committed virtual memory exceeds the limit (`vmcom'
and `vmlim' in the SWP-line), the SWP-line is colored due to
overcommitting the system.
Swap
An occupation percentage of 80% is considered `critical'
because swap space might be completely exhausted in the near
future; it is not critical from a performance point-of-view.
These default values can be modified in the configuration file
(see separate man-page of pcp-atoprc(5)).
When a resource exceeds its critical occupation percentage, the
concerning values in the screen line are colored red by default.
When a resource exceeded (default) 80% of its critical percentage
(so it is almost critical), the concerning values in the screen
line are colored cyan by default. This `almost critical
percentage' (one value for all resources) can be modified in the
configuration file (see separate man-page of pcp-atoprc(5)).
The default colors red and cyan can be modified in the
configuration file as well (see separate man-page of
pcp-atoprc(5)).
With the key 'x' (or flag -x), the use of colors can be
suppressed.
