I disagree. It's not as if Linux hasn't been running on 64-bit systems for a long time now - Alpha was the first non-Intel port IIRC. If there's anything that's going to slow down Linux on S/390 it will be how good gcc does on targeting the virtual processor, and how well the IBM devs have tied in device support - not the fact that it's 64-bit.
With regard to the linked benchmarks, somehow I bet the benchmarkers at Tom's didn't compile parallel. Of course there is not going to be a speed improvement if you don't run a parallel make!
As someone who builds a small embedded Linux system from scratch (including gcc and glibc), a dual processor system is VERY nice. It cuts down the compile time by at least 30-40%. make -j2 is your friend with two processors.
Basically, as I understand it, it allows closer to 100% use of your CPU at any time.
Modern CPU's have many different execution units. Depending on the code running, not all of them may have work scheduled. Future work may depend on previous results; obviously you can't do this in parallel. The idea of "HyperThreading" is to run more than one thread of execution at a time with the multiple execution units - so more work gets done per clock cycle.
A quick Google search turned up an article here.
At one point I read a really excellent article on single-processor multithreading (discussing a future Alpha processor) but I can't find it anymore.
Hopefully AMD will do something like this as well for a future Hammer processor.
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With regard to the linked benchmarks, somehow I bet the benchmarkers at Tom's didn't compile parallel. Of course there is not going to be a speed improvement if you don't run a parallel make!
As someone who builds a small embedded Linux system from scratch (including gcc and glibc), a dual processor system is VERY nice. It cuts down the compile time by at least 30-40%. make -j2 is your friend with two processors.
Modern CPU's have many different execution units. Depending on the code running, not all of them may have work scheduled. Future work may depend on previous results; obviously you can't do this in parallel. The idea of "HyperThreading" is to run more than one thread of execution at a time with the multiple execution units - so more work gets done per clock cycle.
A quick Google search turned up an article here. At one point I read a really excellent article on single-processor multithreading (discussing a future Alpha processor) but I can't find it anymore. Hopefully AMD will do something like this as well for a future Hammer processor.