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Oracle® VM Server for SPARC 3.6 Administration Guide

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Updated: September 2019
 
 

Interaction of Hard Partitioned Systems With Other Oracle VM Server for SPARC Features

This section describes how hard partitioned systems interact with other Oracle VM Server for SPARC features.

CPU Dynamic Reconfiguration

You can use CPU dynamic reconfiguration with domains that are configured with CPU whole cores. However, you can add or remove only entire CPU cores, not individual CPU threads. The hard partitioning state of the system is maintained by the CPU dynamic reconfiguration feature. In addition, if CPU cores are dynamically added to a domain, the maximum is enforced. Therefore, the CPU DR command would fail if it attempted to exceed the maximum number of CPUs.


Note - The max-cores property cannot be altered unless the domain is stopped and unbound. So, to increase the maximum number of cores from the value specified at the time the whole-core constraint was set, you must first stop and unbind the domain.

Use the following commands to dynamically add to or remove CPU whole cores from a bound or active domain and to dynamically set the number of CPU whole cores for a bound or active domain:

ldm add-core number-of-CPU-cores domain

ldm remove-core number-of-CPU-cores domain

ldm set-core number-of-CPU-cores domain

Note - If the domain is not active, these commands also adjust the maximum number of CPU cores for the domain. If the domain is bound or active, these commands do not affect the maximum number of CPU cores for the domain.
Example 70  Dynamically Adding Two CPU Whole Cores to a Domain

This example shows how to dynamically add two CPU whole cores to the ldg1 domain. The ldg1 domain is an active domain that has been configured with CPU whole cores. The first command shows that the ldg1 domain is active. The second command shows that the ldg1 domain is configured with CPU whole cores and a maximum of four CPU cores. The third and fifth commands show the CPU cores that are assigned to the domain before and after the addition of two CPU whole cores. The fourth command dynamically adds two CPU whole cores to the ldg1 domain.

primary# ldm list ldg1
NAME    STATE   FLAGS   CONS  VCPU  MEMORY UTIL  UPTIME
ldg1    active  -n----  5000  16    2G     0.4%  5d 17h 49m
primary# ldm list -o resmgmt ldg1
NAME
ldg1

CONSTRAINT
   whole-core
        max-cores=4
primary# ldm list -o core ldg1
NAME 
ldg1

CORE 
CID	PCPUSET 
1	(8, 9, 10, 11, 12, 13, 14, 15) 
2	(16, 17, 18, 19, 20, 21, 22, 23)
primary# ldm add-core 2 ldg1
primary# ldm list -o core ldg1
NAME 
ldg1

CORE 
CID	PCPUSET 
1	(8, 9, 10, 11, 12, 13, 14, 15) 
2	(16, 17, 18, 19, 20, 21, 22, 23) 
3	(24, 25, 26, 27, 28, 29, 30, 31)
4	(32, 33, 34, 35, 36, 37, 38, 39)

CPU Dynamic Resource Management

Dynamic resource management (DRM) can be used to automatically manage CPU resources on some domains.

CPU Weighted Mean Utilization

DRM uses weighted mean utilization to determine when to perform a CPU DR operation on a domain based on CPU utilization history. The weighted mean utilization value is an average of CPU utilization figures where the most recent utilization figure is assigned a greater weight than less recent utilization figures.

The weighted mean utilization is compared to the util-upper and util-lower DRM properties for each domain policy that is running. A CPU DR operation is performed only if the weighted mean utilization value falls outside of the upper and lower utilization bounds.

Power Management

You can set a separate power management (PM) policy for each hard-partitioned domain.

When PM detects that a domain is idle, it begins to skip cycles to save power. Skipping cycles reduces utilization, which affects DRM. As domain activity increases, PM stops skipping cycles and restores normalized utilization. This transition enables DRM to correctly calculate weighted mean utilization.


Note - These PM transitions, along with DRM heuristics, take several seconds before DRM can dynamically reconfigure domain resources.

Domain Reboot or Rebind

A domain that is configured with CPU whole cores remains configured with CPU whole cores when the domain is restarted, or if the entire system is restarted. A domain uses the same physical CPU cores for the entire time it remains bound. For example, if a domain is rebooted, it uses the same physical CPU cores both before and after the reboot. Or, if the entire system is powered off while a domain is bound, that domain will be configured with the same physical CPU cores when the system is powered on again. If you unbind a domain and then rebind it, or if the entire system is restarted with a new configuration, the domain might use different physical CPU cores.