Re: Informix performance on 1, 2 or 4 processors??

>Kerry Lyall <kalyall@concentric.net> wrote in article ><5im68n$spr@chronicle.concentric.net>... >> Please Help! I am getting conflicting answers. >> >> HP and Informix say performance on 2 processors (1 for OS & 1 for DB) >> is fine. >> >> A user I know says they heard at an Informix Performance Seminar at >> last summers World Wide Conference that performance on 2 processors is >> a "real dog"!! This user says I should be on a 1 or 4 processor but >> NOT 2 processors !!?? >Most of the tribal wisdom I've heard suggests that when running on a 2 >processor machne, configure Informix as if you had only a single processor. >(NUMCPUVPS=1, MULTIPROCESSOR=0 in the onconfig file.) The overhead >associated with the multi-cpu coordination is not worth it when all you are >gaining is one additional CPU. Configured this way, Informix should >perform at least as well on a 2 CPU box as on a one CPU box. The second >CPU will in fact help speed things up some, but intra-query parallelism >(other than possibly parallel scans) will not be utilized. This is true. The MULTIPROCESSOR tag does not affect locking of memory and/or data. What it really does is to place the vp in a spin loop when a resource is locked with the idea that the "other" physical processor will give up the lock quickly. If MULTIPROCESSOR is turned off, then the vp will go to sleep and/or issue a poll/select if the lock is "raised". Also, by setting up two cpuvps on a two processor system will enable you to have two kaiothreads. Madison Pruet