If one core is not using bandwidth then the other gets it all (I assume).
However SMP setups do have additional latencies and stalls due to cache coherency issues. These should not be ignored. Basically if core A has a piece of memory cached and core B wants to access it, then it has to be flushed to memory, that's a lot slower than just keeping it in the cache. how much this occurs depends on the apps being run.
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Originally Posted by bobkoure
Anyone know about game-app architecture? I know a bit about windows and multi-processor interaction, all-be-it pretty dated (WinNT drivers for multi-processor machines - windows architecture hasn't changed much since then but the msoft tools/APIs may have).
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I write games for a living so I guess you could say I know games architecture.
Exploiting SMP is certainly possible in games, but it's not easy by any means. Everything has to run quickly with low latency in general which makes multiple threads difficult. Games are already a juggling act between the CPU and GPU, adding another CPU only adds to the complexity. To an extent though I expect to see things like phyics and similar simulation tasks pushed off to extra cores. Since both XB360 and PS3 are parallel machines this sort of thing will become the norm for games. It won't be long before the PC market follows suit. the main limiting factor is the cost of doing it - games are expensive, adding to the complexity will further increase costs, which means it may get done in a half-assed manner. That could end up worse than not doing anything at all.