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10.7.1 Conditions for Automatically Replacing a CPU Core


10.7.1 Conditions for Automatically Replacing a CPU Core
To perform the automatic replacement of CPU cores, the following conditions must be met.
  1. Of all the CPU cores mounted on a physical partition, at least one core is ensured not to be assigned to the PPAR.
  1. If you allocate all the CPU cores mounted on the PPAR to the PPAR with the setcod(8) command of the XSCF firmware, automatic replacement is unavailable.
    For the SPARC M10-4 (4-CPU x 16-core configuration), for example, 64 CPU cores are mounted on the PPAR. To use the automatic replacement function in this configuration, it is necessary to set the number of CPU cores allocated on the PPAR to 63 or less by using the setcod command.
    When 56 CPU cores are allocated to PPAR-ID 0 as follows, 64 CPU cores are mounted on the PPAR and so cores can be automatically switched.
XSCF> setcod -p 0 -s cpu -c set 56
PROC Permits assigned for PPAR 0 : 0 -> 56

PROC Permits assigned for PPAR will be changed.
Continue? [y|n] :y

Completed.
Note - The XSCF firmware of version XCP 2250 or earlier does not support the -c add, -c delete, and -c set options. Specify the setcod command options as follows to interactively add and delete assignments.
XSCF> setcod -s cpu
  1. The number of CPU cores available for automatic replacement has no relationship to the number of CPU cores registered with the CPU Activation keys. For example, if 56 CPU Activations are registered in the above example of SPARC M10-4, then up to 8 available CPU cores can be switched with the automatic replacement function, even when 56 CPU cores are allocated with the setcod(8) command. In this case, the 8 CPU cores available for switching do not require CPU Activation keys.
  1. CPU cores can be dynamically deleted.

Automatic replacement of CPU cores is unavailable under the following cases.
  1. Physical core IDs (cid option) are specified when CPU cores are assigned to the logical domain.
    Automatic replacement of CPU cores is unavailable if the CPU cores are assigned to the logical domain with the cid option specified as follows.
# ldm set-core cid=20 ldom
# ldm add-core cid=20 ldom
  1. If you have assigned CPU cores with cid specified, remove the cid specification. For the method of removing the cid specification, see "How to Remove the physical-bindings Constraint" in the Oracle VM Server for SPARC Administration Guide of the version used.
Note - To use the CPU automatic replacement function, do not use the Oracle Solaris kernel zones.
When Oracle Solaris kernel zones are in use, CPU cores assigned to Oracle Solaris kernel zones are not automatically replaced in a correct way.
The six subsequent restrictions are abolished in Oracle VM Server for SPARC 3.3 and later.
  1. When only one CPU core is assigned to a logical domain
    Use the ldm set-core or ldm add-core command to assign two or more CPU cores to a domain. You can confirm CPU core resources used by the logical domain with the ldm list-domain -o core command.
  1. When the processor set of the resource pool does not meet the following conditions
    [SPARC M12]
    The pset.min property is set to 9 or more, and the pset.max property is set to pset.min + 8 or more.
    [SPARC M10]
    The pset.min property is set to 3 or more, and the pset.max property is set to pset.min + 2 or more.
    For the method for configuring the processor set of the resource pool, see the System Administration Guide: Oracle Solaris Containers-Resource Management and Oracle Solaris Zones.
  1. When specifying any specific number of CPUs for the dedicated-cpu resource of an Oracle Solaris zone
    Specifying a specific number of CPUs when using the dedicated-cpu resource of an Oracle Solaris zone is incompatible with automatic CPU core replacement.
    (e.g., ncpu=5)
  1. When the range of CPUs specified for the dedicated-cpu resource of an Oracle Solaris zone does not meet the following conditions
    [SPARC M12]
    Nine or more CPUs (two cores) for the minimum value, and the minimum value + eight or more CPUs for the maximum value
    (e.g., ncpus=9-17)
    [SPARC M10]
    Three or more CPUs (two cores) for the minimum value, and the minimum value + two or more CPUs for the maximum value
    (e.g., ncpus=3-5)
  1. When any processes are bound to the CPU core with the pbind command
    You must check/release any processes bound to the CPU core with the pbind command to use the CPU core with the automatic CPU core replacement function.
  1. When processes are bound to only one CPU core with the psrset command
    Assign two or more CPU cores to the processor set, or remove the processor set, releasing the CPU core that you want to use with the automatic CPU core replacement function.