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Cache and Memory Performance

I mentioned earlier that cache latencies are higher in order to accommodate the larger caches (8MB L2 + 8MB L3) as well as the high frequency design. We turned to our old friend cachemem to measure these latencies in clocks:

Cache/Memory Latency Comparison
  L1 L2 L3 Main Memory
AMD FX-8150 (3.6GHz) 4 21 65 195
AMD Phenom II X4 975 BE (3.6GHz) 3 15 59 182
AMD Phenom II X6 1100T (3.3GHz) 3 14 55 157
Intel Core i5 2500K (3.3GHz) 4 11 25 148

Cache latencies are up significantly across the board, which is to be expected given the increase in pipeline depth as well as cache size. But is Bulldozer able to overcome the increase through higher clocks? To find out we have to convert latency in clocks to latency in nanoseconds:

Memory Latency

We disable turbo in order to get predictable clock speeds, which lets us accurately calculate memory latency in ns. The FX-8150 at 3.6GHz has a longer trip down memory lane than its predecessor, also at 3.6GHz. The higher latency caches play a role in this as they are necessary to help drive AMD's frequency up. What happens if we turn turbo on and peg the FX-8150 at 3.9GHz? Memory latency goes down. Bulldozer still isn't able to get to main memory as quickly as Sandy Bridge, but thanks to Turbo Core it's able to do so better than the outgoing Phenom II.

L3 Cache Latency

L3 access latency is effectively a wash compared to the Phenom II thanks to the higher clock speeds enabled by Turbo Core. Latencies haven't really improved though, and Bulldozer has a long way to go before it reaches Sandy Bridge access latencies.

The Impact of Bulldozer's Pipeline Windows 7 Application Performance
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  • Gasaraki88 - Friday, October 21, 2011 - link

    I think the main competitor for Intel in the future is going to be the ARM processor makers. As Intel goes in to that space with the x86 and the ARM chips getting faster and faster and Windows 8 supporting ARM, you get a mix and soon ARM chip will invade the desktop/laptop market.

    AMD is done.
    Reply
  • ppro - Monday, October 24, 2011 - link

    I decided to get this new cpu from www.amd.com Reply
  • navair2 - Monday, October 24, 2011 - link

    I decided to try AMD when I "inherited" my brother's older socket 939 hardware some years ago, then built my own using a Phenom II X4 940 BE.

    At the time it was released, the 940 wasn't too far behind the i7 920 in many respects, plus it was about $70 cheaper...I was very satisfied with my decision. However, after 3 years of advancement by both companies and watching Intel ONCE AGAIN come up with something that gives excellent performance with ever-increasing power reduction, I was on the fence about Bulldozer even before the reviews came out.

    Once I saw the majority of the reviews, I knew what side of the fence to be on for obvious reasons..."Bulldozer" just didn't hit the expectations I thought it should, especially when it comes to load power consumption. Perhaps in a couple years when it matures, but I didn't feel like waiting for AMD to iron out all the wrinkles.

    My next build is already done and sorry to say, it's NOT AMD. For what I do the i5-2500K is just too good to pass up at combo prices that result in a $200 processor ( less than what I payed for my X4 940 when IT was new).

    Best wishes AMD, I hope you can make "Bulldozer" work, but for now "BD" stands for "Big Disappointment". I'll check back with you in a year or so to see how things are doing.
    Reply
  • johnsmith9875 - Tuesday, October 25, 2011 - link

    Intel's first "dual core" was actually 2 processors on one chip.

    They could have saved a lot of engineering time by merely shoehorning two X6 Thuban processors together at 32nm and sell it as a 12 core. Now that would have rocked!
    Reply
  • Poxenium - Wednesday, October 26, 2011 - link

    Does anybody remember the first Intel processors with the entirely new architecture called Core Duo, Conroe-L or something ? They were pretty lousy at first, with slightly higher performance than the previous generation, but constantly overheating. later the Core 2 Duo was a complete success, not to mention the first generation iCore processors and of course Sandy Bridge.
    Considering the fact that these Bulldozer processors are AMD's first attempt at a completely new architecture, I say that both performance and power consumption are at reasonable levels. Upcoming models will surely do a lot better.
    Reply
  • shbdf - Friday, November 04, 2011 - link


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    Handbags(Coach l v f e n d i d&g) $35
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    Reply
  • Wolfpup - Friday, November 04, 2011 - link

    I'd love to see how well the SMP client runs on an "8 core" Bulldozer part compared with a quad Sandy Bridge, and for that matter a 6 core Phenom 2 and 6 core Nehalam.

    It SEEMS like it should do really well, right? Or not? Because basically an 8 core Bulldozer is a quad core when it comes to floating point, right? And Folding uses a lot of floating point? Or...?

    Also, if it really has double the transistor count of Sandy Bridge...where is the performance? It seems like even on heavily threaded stuff it's just kind of about equal with Sandy Bridge, which doesn't seem right....
    Reply
  • JumpingJack - Sunday, November 06, 2011 - link

    Except for the fact even with that 'professional' software the competitor is just as fast or faster consuming 30% less power.

    it is unfortunate for AMD and their fan base bit BD is definitely a dud.
    Reply
  • JumpingJack - Sunday, November 06, 2011 - link

    Considering the power consumption and the reported problems with many games, e.g. Dues Ex, Portal 2, Shogun ... I would see this more appealing around the $180 mark. The 1100T is a better buy if you must do AMD. Reply
  • JumpingJack - Sunday, November 06, 2011 - link

    The statement is partially true. There are quite a few apps that the Thuban outnguns BD and many cases where it out performs on energy effiency as well. Reply

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