21.6.Other Factors

Benchmarks are run with a transaction monitor, usually Tuxedo. This has not been discussed here. Multiprocessor questions have not been addressed either. Virtuoso off the box should scale to about 4 CPU's on any appropriate multithreaded, multiprocessor OS. Past 4 CPU's the returns will diminish.

Operating systems have different caching policies which must be taken into account. If an OS does read ahead, that's OK. Generally OS intelligence is harmful and should be turned off. For example, AIX reacts to its disk write queue being full by turning off the writing process until it has flushed enough of its own file cache. This instead of blocking the writing thread and leaving the rest of the process to run.

We may release more information on OS tuning in the future.