Re: CPU not used when multi-threaded


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

At 05:39 PM Wednesday, The Human Fly wrote: 
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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