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CPU_COUNT specifies the number of CPUs available for Oracle Database to use. On core architectures, it specifies the number of available CPU cores. Various components of Oracle Database are configured based on the number of CPUs, such as the Optimizer, Parallel Query, and Resource Manager.
CPU_COUNT is set to
0 (its default setting), then Oracle Database continuously monitors the number of CPUs reported by the operating system and uses the current count. If
CPU_COUNT is set to a value other than
0, then Oracle Database will use this count rather than the actual number of CPUs, thus disabling dynamic CPU reconfiguration. When Resource Manager is enabled, setting
CPU_COUNT limits the CPU utilization to approximately
CPU_COUNTto a value greater than the current number of CPUs results in an error. However, if
CPU_COUNTis set to a value greater than the current number of CPUs in the initialization parameter file, then
CPU_COUNTis capped to the current number of CPUs.
Oracle Database VLDB and Partitioning Guide for information about how
CPU_COUNT is used to determine the default degree of parallelism for a single instance or Oracle RAC configuration when the
PARALLEL clause is specified but no degree of parallelism is listed
Oracle Database Administrator's Guide for an example of how CPU resources are allocated if you enable instance caging and set a maximum utilization limit in a resource plan