EricTViking wrote:
Snipedya14 wrote:
EricTViking wrote:
Hyperthreading is a way for certain intel processors to appear to do two things at once. It only works for certain apps, and doesn't necessarily give you much of a performance boost.
Hyperthreading is *like* having to processors in your computer. Dual Core *is* having two processors in your computer ;-)
Sorry to double post, but I missed this.
Hyper Threading is not like having two processors. It allots a small amount of CPU clock cycle to another thread. THere is nothing physical, just a sofware change.
Dual cores is however, is not two CPUs. Why? Dual cores share the FSB, etc. They share a bank of memory as well.
I was just trying to explain it in a way that people understand.
But if you're up for it, hyperthreading is not a software change as windows is already a fully pre-emptive multitasking operating system. Any time slicing and thread scheduling is carried out by Windows and not the CPU. Hyperthreading is actually additional hardware circuitry on the CPU that (under certain code conditions) allow two threads to appear to execute at the same time. Hence it is *like* two CPUs.
Dual Core is two CPUs, but they are both on the same core. You get two CPUs on one chip. This is no different to a dual processor system where both CPUs still share resources (memory, HDD, buses etc). Unless you're talking dual Opterons where each CPU may have it's own bank of RAM. So Dual Core *is* two CPUs, they are just both on the same physical chip.
I don't think that's the case. Pentium 4s are dynamic multiple issue processors (superscalar). Hyperthreading is an architecture extension that builds on this idea. What this means is that while one instruction is being executed another, that is likely to follow it, is executed simultaneously in another ALU. Branch prediction is used to determine which instructions are likely to be executed next.
Hyper Threading is an improvement on this dynamic pipelining system. It is microarchitecture based and is not just a software change. It is in fact kind of like having 2 CPUs working on one task - only it's not 2 CPUs just ALUs with shared resources, 7 ALUs on normal P4s.
That's what I always learned in my computer systems archtecture labs anyway.
Snipedya14 wrote:
Dual cores is however, is not two CPUs. Why? Dual cores share the FSB, etc. They share a bank of memory as well.
They tend to have their own memory on chip too. Each core has it's own registers and cache memory and can work independently. It's very close to having 2 physical CPUs. Much closer than a superscalar CPU like the P4, which just has multiple ALUs.
Last edited by Bertster7 (2006-10-16 08:16:48)