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

At 12:54 AM 4/13/97 GMT, Irwin Goldstein wrote: }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. Generally speaking, you would also want to set SINGLE_CPU_VP=1 in this case (when NUMCPUVPS=1). If you do go back to >1 for NUMCPUVPS, you'll get initialization errors so you'll need to set SINGLE_CPU_VP back to 0. In fact, you should *always* be sure to check the values of these three parameters (NUMCPUVPS, MULTIPROCESSOR, and SINGLE_CPU_VPS) on a single processor box as they can really help or hinder performance. Ron Flannery | rflannery@zenacomp.com | President, ZenaComp Incorporated | Michigan Informix User Group http://www.zenacomp.com | http://www.zenacomp.com/miug.html