HardOCP heeft een artikeltje over Symmetric Multi Processing gebakken, waarin in het kort de werking van SMP en Multi-threading wordt uitgelegd. Tevens wordt gekeken naar de voordelen die SMP voor gamers zou kunnen opleveren:
I have heard people refer to a second CPU as a "stand-by" that kicks in when the first CPU is loaded. This is simply not true. There is no difference in the CPUs roles, in fact the CPUs ID of 0 or 1 switches many times per second. Each CPU in a SMP system will share the workload fairly equally, there is always exceptions of course, but generally, this is the case. Now I have heard people say that you need an “SMP capable app” to get a performance increase. This also is not true.
Remember your HAL controls threads, and everything has threads, your OS, your apps, everything. So lets say you bust open Quake 2, which is single threaded. Will you see a performance increase with two CPUs over one? YES. Why? The HAL can dedicate a CPU to the Quake 2 thread, and run the OSs threads through the Other CPU. The Machine will run better. If your run a multi-threaded app, the HAL can grab the threads from that program and execute two threads at once. It will assign one to each CPU. This brings up a key point. If a p2 450 can only run one thread, and a dual p2 450 can run two, then why is there not a 100% performance increase? The two CPUs must talk to each other. This bus overhead causes a drop in the performance of the CPU’s. So, in the end, you get an 80% increase.
Op zich klopt dit natuurlijk wel, alleen ben ik bang dat je er in de praktijk bar weinig van zult merken. Een BP6 met twee Celerons op 500MHz heeft een load van ~0% wanneer alleen Windoos en Explorer draaien .