Re: 2 or 4 cpu's running Informix OnLine 7.xx

Scott Ratliff wrote: > > dkabrbwj@e-mail.com wrote: >snip..... > No, that is not true. What is true is that the engine will run slower > on a two processor machine if you set MULTIPROCESSOR to 1 (true) and > SINGLE_CPU_VP to 0 (false) than if you had set MULTIPROCESSOR to 0 (false) > and SINGLE_CPU_VP to 1 (true). IOW, it is slower on a two processor > machine to configure the engine for multiprocessing than it is to just > tell the engine you only have one. > > Scott Ratliff > Systems Engineer > CARS Information Systems Corp. > scottr@carsinfo.com This concept has been bothering me for some time, so I'll wander out on a limb against the common wisdom and say "I haven't seen it" (at least on our 2 way Sparc 1000E). What I see is that 1 CPU VP corresponds to 1 Unix process under Solaris 2.4. If I only have one CPU VP, only one CPU runs it, the other one sits there doing nothing. When I add the second VP, both physical processors will get busy and throughput improves. To say that adding the second VP (to use the second processor) introduces so much locking/coordination overhead that it's better to just let one physical CPU sit idle seems absurd to me and would constitute a sorry implementation on Informix's part. Yes I know their manuals say this too. It still just doesn't add up for me. Is it possible that the behavior I see is related to Solaris (since I haven't seen other Unixes in a similar config)??? -- Greg Moye Electronic Data Systems Corp. - Plano TX