The Return of Hyper Threading

While Nehalem is designed to scale to up to 8 cores per chip, each one of those cores has the hardware necessary to execute two threads simultaneously - yep, it's the return of Hyper Threading. Thus our quad-core Nehalem sample appeared as 8 logical cores under Windows Vista:


Four cores, eight threads, all in a desktop CPU

Note that as in previous implementations of Hyper Threading (or other SMT processors) this isn't a doubling of execution resources, it's simply allowing two instruction threads to make their way down the pipeline at the same time to make better use of idle execution units. Having 8 physical cores will obviously be faster, but 8 logical (4 physical) is a highly power efficient way of increasing performance.

We took Valve's source-engine map compilation benchmark and measured the compile time to execute one instance (4 threads) vs. two instances of the benchmark. The graph below shows the increase in compilation time when we double the workload:

Valve Map Compilation Benchmark - 4 to 8 Thread Scaling

While the 2.66GHz Core 2 Quad Q9450 (Penryn) takes another 127 seconds to execute twice the workload, the 2.66GHz Nehalem only needs another 49 seconds. And if you're curious, this quad-core Nehalem running at 2.66GHz is within 20% of the performance of an eight-core 3.2GHz Skulltrail system. Equalize clock speed and we'd bet that a quad-core Nehalem would be the same speed as an 8-core Skulltrail here. The raw performance numbers are below:

Valve Map Compilation Benchmark 

We couldn't disable Hyper Threading so we reached the limits of what we were able to investigate here.

The Socket A Quick Path to Memory
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  • SiliconDoc - Monday, July 28, 2008 - link

    Crysis- etc. :

    Pete, you can be very happy knowing it will do folding like mad, and you can fantasize that you've cured cancer while you spend your money for some tax subsidized already to the hilt University program, because you're such a good and loving person.
    ( I know YOU didn't mean anything like that - see sarcasm! )
    In the mean time, the OLD HT single core chips will do just fine cranking most games, and dual core or core2duo or 2180 or some other then $40 chip will be a few percentage pts. shy.
    My gawd, they've got our number.
    I bet they "unlock it !!!!! " OMG ! for like 2 grand if you're cooooool you can get one!
  • Crank the Planet - Thursday, June 5, 2008 - link

    I know it may be exciting but the article sounds fan-boyish. For most of the marks it shows what intel is claiming 20-30% boost. He gets one mark to go 50% and now it's 20-50% boost?? He compares in another mark AMD 21 and nehalem 14 and says it's almost 50% faster!!! and then compares penryn 18 and nehalem 14 and says it's 28%. I think the AMD mark was more like 35%.

    As I've said before everybody knows AMD was going to hurt themselves in the short run by buying ATI. If they didn't buy ATI I think things would be very different. Now that the last year of payments is being made for buying ATI AMD will be able to get back into the game.

    Intel has only now integrated the memory controller. Everybody knew as soon as they did they would see a nice bump. They haven't had any significant innovations in a long time. AMD is in the same position they were before K8. Just give them some time to finish absorbing ATI, then watch out- fusion is just around the corner :)
  • hs635 - Tuesday, June 17, 2008 - link

    Fuck off retard
  • masouth - Friday, June 6, 2008 - link

    What kind of idiot fan-boy drivel is this?

    "He gets one mark to go 50% and now it's 20-50% boost??"

    Ummm, yes?

    1, 2, 3, 4, 8

    What is the range of those numbers? 1-8, right?

    Does the majority of them being being in the 1-5 range somehow negate the fact that the actual range is 1-8?

    THINK PEOPLE!
  • michael2k - Thursday, June 5, 2008 - link

    You're the one that sounds like a fanboy.

    What makes you think Intel's CPU-GPU integration won't be as fabulous as their IMC or quad-core components? Intel doesn't need "significant innovations" (nor does AMD), they just need higher performance, lower power, and lower cost, which is exactly what they have.

    Innovations only exist to serve those aspects.
  • Justin Case - Sunday, June 8, 2008 - link

    Wrong.

    AMD64 (the instruction set) isn't about "more performance". Virtualization isn't about "more performance". Hardware no-execute flags aren't about "more performance". SATA's hot-plug ability isn't about "more performance".

    Your statement shows the kind of lack of vision that brought us the Pentium 4.

    I for one am far more excited about technology that allows me to do something new or different than "technology" that simply lets me do the same stuff faster. 99% of CPU cycles in the planet go unused anyway.

  • zsdersw - Thursday, June 5, 2008 - link

    Given the overall tone of your reply, the criticism of the article as "fan-boyish" is, really, the pot calling the kettle black.
  • Visual - Thursday, June 5, 2008 - link

    so you agree as well? yeah, me too.
    they are both black. they are both fanboys :)
  • zsdersw - Thursday, June 5, 2008 - link

    I've said nothing about agreeing with anything. What I have said, though, is that a fanboy calling someone else a fanboy is perhaps not indicative of any objective truth.
  • Jynx980 - Saturday, June 7, 2008 - link

    It will be a great day when I can read any CPU discussion without the word fanboy in it.

    The close up of the chip has waaaaaay to much thermal compound on it.

    Is it just me or is the first pic of the Intel roadmap rather... phallic?

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