Actually the higher clocks on the Xeons (plus better IPC) gives the Xeons a slight advantage in most situations. A small boost, but a noticeable one nonetheless. However, for how powerful the Opterons are, their price tag is much nicer than Intel's without much loss in performance. AMD does multi-threading and multi-"core" well. (When I say multi-core, I'm really meaning CPUs in general that support some form of symmetric multi-processing). AMD has a much better bang for your buck with excelling in a number of tasks, where Intel does come ahead on more of these tests,
you're paying almost twice as much from your entry 8-core Intel CPU. So consider for a moment, if you can pay for two 16 core server CPUs for the price of one Xeon.
So lets consider the things that
each does best.
Xeon:
Good IPC
High Clocks
8 real cores, plus 8 non-linear scaling threads (
consider that HT performance is not consistent and can suffer when doing similar tasks at once).
Opteron:
Lower price
16 "almost real cores", (
Integer ops here are the best, floating point ops aren't as powerful but you know how much every module will give you as far as performance is concerned.)
So with all of this said, yeah Intel might be a little bit faster per thread because of the improved IPC but AMD is getting really good at cramming a lot of cores on to a CPU. HyperThreading is great but if you're using the same parts of the CPU for both threads that are running you're performance could suffer on your HT threads. At least with AMD all 16 of those threads have dedicated resources with the exception of the floating point unit, but even that can be efficiently used with the proper instructions.
So all in all, as a System Admin, I would rather have an Opteron for a database or a computing cluster where for an application server, a Xeon might be better. For storage, I would opt whichever used the least power in combination with the price tag.
So how about everyone who is uninformed doing this bulls**t move of "AMD Opteron is better!" and "Intel Xeon is better!" just drop it. Both the Xeons and Opterons are both very good processors and do certain things better than the other.
Might want to ask BuckNasty about his one and about to be two 4P Opteron servers using the older magny cours 12 core procs, that's 48 cores. I'm willing to be he paid no more for that entire machine than for one middle model 8-core Xeon. The Xeon might be faster, but the big question is, would it be worth it and is it cost effective.
Actually, one Intel HT core > one AMD module in most multithreaded workloads.
http://www.anandtech.com/bench/Product/287?vs=434
Most of that performance mostly isn't off the hyper-threading. It's also highly task dependent. Consider for a moment if your "core" is using the ALU to add and your HT thread wants to add too, the HT thread has to wait until the core "thread" is done adding. Then the HT thread goes to add, and if the core has to do it again, it will have to wait for the HT thread. (This is more true of instructions that take more than a couple cycles, so ADD isn't an accurate one because I'm pretty sure both Intel and AMD ALUs do integer ADDs in one cycle.) The general point being, is that AMD CPUs scale almost linearly as more workload is applied to the server, where Intel servers with HT enabled do not.
