Re: SMP

Batch processes, or any single thread of execution, will not improve at all from the introduction of a multi-cpu machine. This is because unless you have the PQO (Parallel Query Option) in Oracle v7.X; each single thread of execution is accomplished by one process which is serviced by only one cpu at a time. The benefit of multiple cpu's would be the ability to execute more than one thread of execution - i.e. more than one batch job - at the same time. With the PQO Oracle would break up a single thread of execution and service it with multiplle server processes - each of which could execute on a cpu.

In terms of your slower running batch loads, check the following:
-block size: if block size is smaller than on single cpu machine it will
take more physical disk writes and more time unless the disk subsystem on SMP machine is faster then on single cpu machine.
-swapping: it may be that you are running more non-batch load processes
while the batch load is running, therefore the avg. cpu time per unit of real time (time on the 24hr clock.) allocated to the load is reduced. Do something like a vmstat on the machine to see the number of context switches occurring during your load execution.

Remember, for a single process - or thread of execution - an SMP machine will not increase the real performance of that process. The perceived performance may be increased if in the single cpu machine there was a lot of cointext switching - too many processes competing for the single cpu. Received on Tue Feb 21 1995 - 04:59:32 CET