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I Have A Few Questions About Hyper Threading & Hyper Transport

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  • CPUs
  • AMD
  • Intel
Last response: in CPUs
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June 25, 2009 10:21:55 PM

Something I'm been curious about is hyper threading only Intel and Hyper Transport only AMD?

Whats the advantages and disadvantages with hyper threads / hyper Transport or they the same?
I know Intel using hyper threads for a few of their cpu lines and I know AMD uses hyper transport in almost all of their cpus.
But was curious if its a trade mark or just a feature?

Can there be a processor with both?

Thanks in advance.

More about : questions hyper threading hyper transport

a b à CPUs
June 25, 2009 11:42:36 PM

They are completely different, actually. Hypertransport is a high bandwidth, low latency connection from the CPU to the motherboard/northbridge. It is AMD only. However, Intel's QuickPath Interconnect (QPI) is quite similar, serving the same purpose with the same to slightly higher performance. Hyper threading is the ability of a processor to run two threads simultaneously in a single processor core, allowing for higher throughput on extremely threaded workloads. Currently, the only CPU available with (effectively) both is the Core i7, which has both QPI and hyperthreading.
a b à CPUs
June 25, 2009 11:46:54 PM

warcloudff said:
Something I'm been curious about is hyper threading only Intel and Hyper Transport only AMD?

Whats the advantages and disadvantages with hyper threads / hyper Transport or they the same?
I know Intel using hyper threads for a few of their cpu lines and I know AMD uses hyper transport in almost all of their cpus.
But was curious if its a trade mark or just a feature?

Can there be a processor with both?

Thanks in advance.


Hyperthreading is a way for the Nehalem CPUs from Intel to execute 2 threads on one core. Basically when you have a thread that uses 60% or less of a core's capacity (i.e., the thread is waiting around for some data, perhaps from another thread, user input, etc), then by storing the core state and switching to another thread, you keep the core closer to 100% busy. This requires extra transistors of course to decode and keep track of multiple threads, but the bulk of the core gets used more efficiently. So, for an additional 5% or so transistors, you get enhanced throughput for those apps like video encoding that can support multiple threads. If for example you had a Core i7 920 Nehalem CPU, and looked at Windows task manager, you'd see 8 logical cores instead of just 4 physical ones which is what it actually has.

Of course, a lot of software, especially older games, is still single-threaded and hence hyperthreading is basically a wasted resource; instead the Nehalem architecture supports turboboost where the clock is sped up on the physical core (assuming the total CPU load is under the thermal limit) and hence the single thread is executed faster.

Hypertransport is a high-speed direct-connect architecture that provides high bandwidth and low latency, and is used on AMD CPUs since the K8 IIRC. Compared to Intel's front-side bus architecture used prior to Nehalem CPUs, it provided advantages in quad or higher socket servers due to the higher bandwidth to memory and between sockets.

Intel now has a similar high-bandwidth low-latency direct connect architecture, only named QPI, on Nehalem CPUs, so yes there is a processor with both technologies.

Rumor has it that AMD may consider hyperthreading in their upcoming Bulldozer CPU, which is supposed to be a new architecture.
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June 26, 2009 12:04:18 AM

Thanks to both of you. This is very helpful. I'm trying to learn what I can. I love this forums so much information heh. Anyways. Have a good day!
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