Re: SMP and 7.x performance questions?

Dave Kosenko wrote: > A small SMP is a bit problemmatic, though. For some reason, it gets hard to > load balance across only 2 cpus. For those in such a situation, I recommend > trying to tun the system as though it were a uniprocessor (set the SINGLE_CPU > parameter on). This introduces some optimizations through the code stream > (avoids doing things that are only pertinant in a multi-proc environment) > that can help. Once you are 4 procs or better, though, you are better off > tuning for SMP. I already heard in several places that SMP will only work well up to 8 CPU. If this theory is correct, we should only use SMP with 4 to 8 CPU's, then start with MPP loosely-coupled architectures. Now back to Informix... This 7.1 performance problem in few CPU machines raises another question: should we use disk fragmentation in those cases? I believe this must be considered carefully because disk fragmentation is strongly dependent on parallel execution. For example: I think that round robin fragmentation is not worth with low number of CPU's, but hashing is a good policy because of the method of skipping fragments. Any ideas on this?