Our server is typical OLTP (online brokerage system), current HW (dual Xeon 2.6 GHz, 5GB RAM) is under heavy load, mainly CPU and it seems that application is quite well optimized, so it seems like adding processors is way to go. So we want to upgrade to 4 way server, we want to stay on x86 and Linux OS.
As far as I know, we can choose between Intel Xeon, Intel Xeon MP and AMD Opteron. Xeon has smaller L3 cache than Xeon MP (2MB vs 4MB), but has higher bus speed (800 MHz vs 400 Mhz) and slightly higher frequency (3.6 GHz vs 3.0 GHz). Opteron has even higher bus speed (1.6 GHz), smaller cache (1 MB), I can use 64-bit ASE, but I'm not sure, if it's proven in production systems. Which option would you recommend ? What's more important for performance - bigger cache or faster CPU - RAM transfers ? Do you have experience with production systems on Opteron server ?