Windows NT - multi-CPU - Question

I have a very busy 4 CPU Pentium II 450 machine running IDS 7.30 TC7. One of the odd things is that if I do something very I/O bound the CPU seems to be pegged (for example queries against a cold buffer cache). Other database products exhibit the opposite behavior, for example if they're I/O bound they don't peg the CPU. Is this just flaky Informix on an NT multi-processor? Are there some knobs I can twist to change this? From the docs is seems that Informix on NT uses async I/O which executes within the CPU VPs, but I wonder why async I/O pegs the CPU? Does it work the same way on UNIX - lot's of I/O kills the CPU? Another example is that I upgraded to 4 CPUs from 2 CPUs and my checkpoints don't run any faster, but they now peg 4 CPUs instead of 2. Cheers

On 28 Jul 1999 12:32:05 PDT, Jay Walters <jwalters@computer.org> wrote: >I have a very busy 4 CPU Pentium II 450 machine running IDS 7.30 TC7. >One of the odd things is that if I do something very I/O bound the CPU >seems to be pegged (for example queries against a cold buffer cache). >Other database products exhibit the opposite behavior, for example if >they're I/O bound they don't peg the CPU. Is this just flaky Informix >on an NT multi-processor? Are there some knobs I can twist to change >this? > >From the docs is seems that Informix on NT uses async I/O which executes >within the CPU VPs, but I wonder why async I/O pegs the CPU? Does it >work the same way on UNIX - lot's of I/O kills the CPU? > >Another example is that I upgraded to 4 CPUs from 2 CPUs and my >checkpoints don't run any faster, but they now peg 4 CPUs instead of 2. From memory there's a way to bypass kaoi, and force the use of aio vps. I'm not sure if this will help, but it might be worth investigating. Ciao Fuzzy :-)