You're more or less right. HT is just a cute little trick to help optimize the utilization of a single CPU. It doesn't even begin to compare to just throwing an extra processor at the problem though. (SMP)
It's just another way of tackling the same problem that has plagued software developers for ages. Do you design a smart compiler to order everything well in your code? Do you use a profiler to order your own code so well that it always uses as much as possible of the CPU? Or do you use HT and let the OS and processor try to do it for you ... so long as you write multi-threaded applications and/or run multiple applications simultaniously.
If you write single-threaded apps and only optimize your code or compiler, then the CPU is still slow when it tries to run two programs at once because your code is designed to be run only by itself.
If you use HT, then so long as you're running multiple threads, the processor and OS work out fairly useful (but not always the absolute best) optimizations on their own. But of course you may never get the absolute best possible performance from code tweaking that way, and writing multi-threaded code is a laborous process that also incurs a minor performance pentalty to manage the threads harmoniously and makes code much more bug prone from thread timing problems.
Neither way is a perfect solution. However, Intel would have us believe that HT at least is more effective than using a profiler to optimize your own code. Never mind that programmers who have done so have single-threaded code that runs better without a HT chip than multi-threaded code on a HT chip of the same speed.
So really, the best way to increase performance is still to use SMP. Give more resources for threads to consume and of course the software will be faster. It's costly though. Hence the other methods that are more cost effective.
More importantly, HT (in theory) makes writing multi-threaded code a lot more beneficial for software developers now. So (in theory) most software developers will start writing multi-threaded code, and then we'll live in an Intel-utopia where software always runs about twice as fast on a dualie system than it does on a single-CPU system because all software is multi-threaded. (As opposed to the current dualie-hell where most software is single-threaded and thus by nature can only use the resources of one processor, so these apps run about the same speed on a dualie system as they do on a single-cpu system.)
Once Intel's utopia comes into place, then of course <i>everyone</i> will want a dualie system at the very minimum, and thus Intel makes at least twice as much money per system sold. Heh heh.
So basically HT is Intel's lure to get software engineers to pave the road to Intel's utopia.
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