>A dual-core 2.6 Opteron is about US$1079. whereas >a single core is about $460. So for about $200. >more I can build 2 2.6Ghz systems that give me a >lot more bang for my buck than 1 dual-core >system.
Well, the bleeding edge is always at a premium. But you mention a wall. A wall doing what? Single threaded monte-carlo? Single postgres query? Almost any real-world load that will stress a modern server box comes from multiple requests. As for pf performance - who the hell cares? Are you routing between two 10GBit LANs? If you're using that much CPU, then if you care what OS you're using, your app is badly written, cos you should first avoid entering the kernel anyway as much as you can. Personally I value a good pthread/libc much higher than parallelism in the kernel for exactly this reason.