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Load average is a traditional UNIX metric. Load average value is the average
number of processes that are either in a runnable or uninterruptable state
during a particular time period. The three numbers shown are load averages for
the last 1, 5, and 15 minutes.
A process in a runnable state
is either using the CPU or waiting to use the CPU. A process in uninterruptable
state is waiting for some I/O access, eg waiting for disk.
The averages are taken over the three time intervals. Load averages
are not normalized for the number of CPUs in a system, so a load average
of 1 means a single CPU system is loaded all the time while on a 4
CPU system it means it was idle 75% of the time.
== How to get container's load average ==
For a single specific container:
vzctl exec $CTID cat /proc/loadavg
For all or specified containers
vzlist -o ctid,laverage [CTID ...]
See {{Man|vzlist|8}} for details on vzlist.
== Reasons for high load average ==
Two reasons for high load average is lack of CPU time or disk I/O bandwidth.
For container, it can also be because of its limits, such as the CPU limit
or low disk I/O priority.
For [[VSwap]]-enabled containers, one case is the lack of RAM (physpages).
Whenever a RAM shortage occurs, system will start doing virtual swapping,
delaying a given container to emulate the effect of a real swap-out.
[[Category: HOWTO]]
number of processes that are either in a runnable or uninterruptable state
during a particular time period. The three numbers shown are load averages for
the last 1, 5, and 15 minutes.
A process in a runnable state
is either using the CPU or waiting to use the CPU. A process in uninterruptable
state is waiting for some I/O access, eg waiting for disk.
The averages are taken over the three time intervals. Load averages
are not normalized for the number of CPUs in a system, so a load average
of 1 means a single CPU system is loaded all the time while on a 4
CPU system it means it was idle 75% of the time.
== How to get container's load average ==
For a single specific container:
vzctl exec $CTID cat /proc/loadavg
For all or specified containers
vzlist -o ctid,laverage [CTID ...]
See {{Man|vzlist|8}} for details on vzlist.
== Reasons for high load average ==
Two reasons for high load average is lack of CPU time or disk I/O bandwidth.
For container, it can also be because of its limits, such as the CPU limit
or low disk I/O priority.
For [[VSwap]]-enabled containers, one case is the lack of RAM (physpages).
Whenever a RAM shortage occurs, system will start doing virtual swapping,
delaying a given container to emulate the effect of a real swap-out.
[[Category: HOWTO]]