Although Oracle sets CPU_COUNT based on the number of CPUs it finds and then uses that to determine some dependent parameters [eg LOG_SIMULTANEOUS_COPIES], it does not physically tie itself to the number of CPUs. Thus, you could always change CPU_COUNT {now _cpu_count ??} and LOG_SIMULTANEOUS_COPIES in earlier releases. AFAIK, there is nothing in the Oracle code or instance parameters to limit itself to a certain number of CPUs.
On Unix, Oracle actually runs multi-processes. It is for the OS Scheduler to assign processes to different CPUs {although you can use OS commands to specify CPU-affinity}.
Hemant
List,
For one of our business critical database, we have assigned 12 cpus with multi-thread(logical) of 24 cpus. What we have noticed that oracle is not using all the CPU avaibale, at least 4 (8 logical) cpus are not being utilized. We have checked from OS level using sar report to confirm the sam during business peak hours. Is there any limitation with oracle not to use many logical CPUs?
Hemant K Chitale http://web.singnet.com.sg/~hkchital
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