Re: Informix dual processor scalability

: smb@oasis.icl.co.uk (Stuart Britt) writes: : Does anyone have any info on the following problem? We are using Informix : version 7.10.UC1 for Intel UnixWare 2.01 on single processor and SMP : machines. : : Using Informix on 1 processor we achieve good performance. If we switch to : 2 processors, then our performance actually degrades. We have been given : some advice on tuning the system for dual processor machines and we have : tried different settings for virtual processors and processor affinity. : We managed to get an improvement, but the best scaling we can get is : about 1.25. : : If we move to a quad processor system the problem goes away and we : approach expected performance levels. : : Has anyone else experienced this? This conforms exactly to what Informix said at the user conference this summer. According to that you can't rely expect any performance increase until you have 4 processors. This is due to extra resources required to do the swiching between virtual processors takes up more time than you save by an adittional processor. Not long ago someone also said that on SCO Unix even a 4 processor configuration didn't give that much increased performance. As we also use Intel hardware and plan to upgrade to multiple processors it would be very interesting for us to here what your performance increase is. (What does "approach expected performance levels" mean in numbers?) Nils.Myklebust@ccmail.telemax.no NM-data, Aasesvei 71, 1300 Sandvika, Norway My opinions are those of my company