Re: NUMCPUVPs and number of physicial processors

> > We are migrating our Informix 7.23 systems from a SUN 2000 with >14 processors (88 Mhz) to a SUN 6000 with 10 processors (250 Mhz). In >our current configuration, we have : > >NUMCPUVPS = 12 >CLEANERS = 12 >LRUS = 12> > We do not use processor affinity. > > The system is primarily used for decision support. There are a >few very low volume OLTP apps running. > > Should we lower these settings to 10 or less each? If we left >these settings alone, could we expect a performance degradation >resulting from having more CPUVPs than physical processors? > > I'm considering creating two instances on the new SUN 6000. One >instance for the small OLTP apps, and one instance for the DSS data. If >I choose this route, could I go with 8 cpuvps for the DSS and 2 cpuvps >for the OLTP apps or possibly 6 and 4? > > Currently, performance is excellent. So, you ask why upgrade? >The upgrade is a result of expected load increase resulting from a new >decision support project to be implemented after the migration. > > Any comments are appreciated. Thanks in advance. > >> I see no reason to have more CPUVPS than physical CPUs. The only reason that this has been done in the past is because if there are a lot of client applications running on the same box, there can be UNIX process scheduling conflicts occuring at the OS level. By increasing the number of CPUVPS, there is a higher probability that the CPUVP process will go into a block state and raise it's priority. This was done a lot in the early phases of NOAGE. This is not nearly so much of a problem now. Your environment would probably not be running so many client applications since it is non-OLTP. So - it probably would only increase the OS overhead to have more CPUVPS than physical CPUs. Madison Pruet