Parallelization on muli-CPU hardware?

[Neil Hodgson]

Steve Holden:

> Until that time I hadn't realized that the laptop was built on a
> multi-core processor.

   It is more likely you had a machine that featured 'hyperthreading' which
is much less than multiple cores. Somewhere between two sets of registers
and two processors.

> Fortunately the task was easily partitioned into
> two independent processes, each dealing with a separate set of database
> rows, so the run completed well under the necessary 24 hours.

   Did you measure a real performance increase, that is, elapsed time to
completion of job? Many benchmarks show minimal or even negative performance
improvements for hyperthreading. Relying on secondary indicators such as CPU
busyness can be misleading.

   Neil