Pentium 4 hyperthreading

Posted in 2004

Ben Thompson — Fri, 30 Jan 2004 15:54:14 +0000 — source: Usenet: comp.databases.informix

I was wondering about appropriate onconfig settings for Pentium 4 Xeon processors with hyper-threading. Linux seems to treat a Pentium 4 Xeon as two processors: when you cat /proc/cpuinfo you see twice as many CPUs as you actually have. So when setting up the VPCLASS parmater in onconfig should you treat a single Xeon as one or two CPUs. I would guess two since the OS is certainly reporting two to applications. Does anyone know for sure or can anyone point me to an appropriate document on the subject? I am using Linux 9.40.UC2 on SuSE Linux 9.0, kernel 2.4.21-166-smp4G, glibc 2.3.2-87. Also, is there any way of getting KAIO working with this combination. The stock SuSE kernel supports this feature unlike the standard Linux kernel. I have tried setting the KAIO environment variables but it doesn't work so I imagine the answer is a no. This is afterall what the release notes suggest. Ben.