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15.1 Changing the Virtual CPU Configuration


15.1 Changing the Virtual CPU Configuration
This section describes how to change the virtual CPU configuration by using the dynamic reconfiguration (DR) function of Oracle VM Server for SPARC.
Note - To dynamically change logical domain resources, the Logical Domain Dynamic Reconfiguration (drd) daemon must be running on the target domain.
On the SPARC M12/M10 systems, various business processes run on each logical domain. The virtual CPU configuration can be flexibly changed according to the system operation status. In some active processes, the load is concentrated into a given logical domain, so performance with only the configured virtual CPUs used can be considered to be lower. In such a situation, the logical domains in the same physical partition can keep the system operating. This is done by dynamically assigning the virtual CPUs of domains that have a relatively low load.

The virtual CPU configuration can be changed for each thread.

To change the virtual CPU configuration, first use the ldm remove-vcpu command to delete virtual CPUs from logical domains that have a relatively low load. Then, use the ldm add-vcpu command to add virtual CPUs to logical domains that present concerns about lower performance due to increased load. Execute these commands with the root privilege.
Deleting a Virtual CPU
primary# ldm remove-vcpu number ldom
For number, specify the number of virtual CPUs to delete. You can specify it in units of threads. For ldom, specify the logical domain from which to delete the virtual CPUs.
Adding a Virtual CPU
primary# ldm add-vcpu number ldom
For number, specify the number of virtual CPUs to add. You can specify it in units of threads. For ldom, specify the logical domain to which to add the virtual CPUs.
Operation Procedure
  1. Switch from the XSCF console to the control domain console to which the target logical domain belongs.
    For details on how to switch to the control domain console, see "8.3 Switching to the Control Domain Console From the XSCF Shell."
  2. Check the number of virtual CPUs in each domain with the ldm list-domain command.
    The following example checks the status of the primary, ldom1, ldom2, and ldom3 logical domains.
primary# ldm list-domain
NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME
primary active -n-cv- SP 8 4G 3.1% 1d 36m
ldom1 active -n---- 5001 16 2G 34% 1m
ldom2 active -n---- 5002 16 1G 34% 17h 48m
ldom3 active -n---- 5003 24 4G 17% 17h 48m
  1. Delete a virtual CPU from a domain with the ldm remove-vcpu command.
    The following example deletes eight virtual CPUs from ldom3.
primary# ldm remove-vcpu 8 ldom3
  1. Add a virtual CPU to a domain with the ldm add-vcpu command.
    The following example adds eight virtual CPUs to ldom1.
primary# ldm add-vcpu 8 ldom1
  1. Check for a configuration change in the number of virtual CPUs in each domain by using the ldm list-domain command.
    In the following example, check for configuration changes in the primary, ldom1, ldom2, and ldom3 logical domains.
primary# ldm list-domain
NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME
primary active -n-cv- SP 8 4G 3.1% 1d 36m
ldom1 active -n---- 5001 24 2G 34% 1m
ldom2 active -n---- 5002 16 1G 34% 17h 48m
ldom3 active -n---- 5003 16 4G 17% 17h 48m
  1. You can see that virtual CPUs have been deleted from ldom3 and added to ldom1.
  2. Log out from the control domain console to return to the XSCF console.
    For details on how to return to the XSCF console from the control domain console, see "8.4 Returning to the XSCF Shell From the Control Domain Console."