All the existing parameters are listed in the UBC parameters table.
By importance, the parameters are divided into 3 groups: primary parameters, secondary parameters and auxiliary parameters. More detailed description of the parameters and the resource control mechanisms governed by the parameters is provided in the appropriate articles.
General information about all parameters
All resource control parameters have some common properties and some differences.
- Most parameters provide both accounting of some system resource
and allow controlling its consumption.
The exceptions are
physpages(accounting only) and
vmguarpages(no accounting, control only), explained below.
- Each parameter has 2 configuration variables, called
limit. Although both 2 variables are changeable, only one or none of them may be effectively used for the resource control for some parameters. For example,
physpagesis an accounting-only parameter and both its configuration variables are not effectively used in the current OpenVZ version. The description of each parameter explains the meaning of the
limitand what they should be set to if they are not effectively used. In general, for all parameters the
barriershould not be greater than the
- The parameters control
how the resources are distributed between containers in terms of
- limits, i.e. upper boundaries on what this container can consume, and
- guarantees, i.e. mechanisms ensuring that this container can get the assigned “resources” regardless of the activity and the amount of resources required by other containers.
guar” in their names, i.e.
oomguarpagesare container's guarantees. They guarantee availability of resources and certain service level up to the value, specified by the
barrier, and do not guarantee above the
barrier. However, these parameters do not impose usage restrictions. The guarantees are discussed in more detail in the paragraphs describing these parameters. The
oomguarpagesshould be set to the maximal value LONG_MAX.
For some resource limiting parameters, such as
limitsettings are effectively used. If the resource usage exceeds the
barrierbut doesn't exceed the
limit, vital operations (such as process stack expansion) are still allowed to allocate new resources, and other ones are not allowed. A gap between the
limitgives applications better chances to handle resource shortage gracefully. For other resource limiting parameters, such as
limitshould be set to the same value.
Each parameter has “natural units of measurement” — the units
of measurement of values shown via
/proc/user_beancountersinterface and accepted by vzctl. Values related to parameters with names starting with
numare measured in pieces. Values related to parameters with names ending with
pagesare measured in memory pages (memory page is equal to 4 kilobytes on IA-32 hardware). The remaining values (parameters ending with
buf) are measured in bytes. See more at UBC parameter units.
The properties of parameters are summarized in UBC parameter properties.
|Note: Continue reading with UBC primary parameters, UBC secondary parameters and UBC auxiliary parameters.|