Plugin LPAR
| Name: | LPAR plugin |
|---|---|
| Type: | read |
| Callbacks: | config, read |
| Status: | supported |
| FirstVersion: | 5.0 |
| Copyright: | 2010 Aurélien Reynaud |
| License: | GPLv2 |
| Manpage: | collectd.conf(5) |
| See also: | List of Plugins |
The LPAR plugin collects information from logical partitions (LPARs), a hardware virtualization technique of IBM POWER CPUs.
Currently the plugin focuses on collecting detailed and accurate CPU statistics, since CPUs are the most flexibly shared resource in a virtualized environment. LPAR knows shared partitions where a pool of CPUs is shared dynamically between a set of partitions and dedicated partitions where CPUs are assigned statically to a specific partition. Of course, partitions of both modes can coexist on the same hardware.
Each shared partition is entitled to a certain amount of processing power. This entitlement is specified in terms of physical CPUs. A partition may be entitled to the processing power of (1.5) CPUs, for example. If the partition is using less cycles than it is entitled to, the spare capacity may be assigned to another partition. It is therefore normal to have little idle cycles in such a partition and the number of cycles per second may vary greatly depending on the load of other partitions.
If a shared partition is uncapped, it may consume surplus processing power beyond its entitlement. Capped partitions may not consume more processing power than they are entitled to, even if there idle processors available in the pool.
Dedicated partitions have physical CPUs statically assigned to them. They are a lot less interesting from the point of view of the plugin, because you can use the CPU plugin in those partitions. It is possible to activate some sort of "CPU sharing" on those partitions, too. This donating and stealing is reported by the plugin, of course.
<Plugin "lpar">
CpuPoolStats false
ReportBySerial false
</Plugin>
Example CPU graph of a logical partition. The graph was generated with a development version of the plugin.
- libperfstat(3)