Power Optimizations

It is well known that the Haswell has been optimized for low idle power. Servers run at idle a lot less than mobile devices and thus more power management capabilities were needed. 

In Haswell EP, Intel introduces per core p-states (PCPS). PCPS is not necessarily a blessing, as a wrongly chosen p-state can result in higher response times. However, Intel is convinced PCPS will save power or will at least shift the power to where it is needed: to other cores or to the uncore (rings). 

Floating Point intensive code is known to cause power peaks. AVX has doubled the theoretical FLOPS, and the FMA (Fused Multiply Add) of AVX 2.0 promises to double it again. 

To cope with the huge difference between the power consumption of Integer and AVX code, Intel is introducing new base and Turbo Boost frequencies for all their SKUs; these are called AVX base/Turbo. For example, the E5-2693 v3 will start from a base frequency of 2.3GHz and turbo up to 3.3GHz when running non-AVX code. When it encounters AVX code however, it will not able to boost its clock to more than 3GHz during a 1 ms window of time. If the CPU comes close to thermal and TDP limits, clock speed will drop down to 1.9GHz, the "AVX base clock".

Here, Intel illustrates how this will work for their top SKU, the Xeon E5-2699 v3. Notice the lower base clock for AVX code (1.9 vs 2.3).

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  • Kevin G - Monday, September 08, 2014 - link

    As an owner of a dual Opteron 6376 system, I shudder at how far behind that platform is. Then I look down and see that I have both of my kidneys as I didn't need to sell one for a pair of Xeons so I don't feel so bad. For the price of one E5-2660v3 I was able to pick up two Opteron 6376's. Reply
  • wallysb01 - Monday, September 08, 2014 - link

    But the rest of the system cost is about the same. So you get 1/2 the performance for a 10% discount. YEPPY! Reply
  • Kevin G - Monday, September 08, 2014 - link

    Nope. Build price after all the upgrades over the course of two years is some where around $3600 USD. The two Opterons accounted for a bit more than a third of that price. Not bad for 32 cores and 128 GB of memory. Even with Haswell-E being twice as fast, I'd have to spend nearly twice as much (CPU's cost twice as much as does DDR4 compared to when I bought my DDR3 memory). To put it into prespective, a single Xeon E5 2999v3 might be faster than my build but I was able to build an entire system for less than the price Intel's flagship server CPU.

    I will say something odd - component prices have increased since I purchased parts. RAM prices have gone up by 50% and the motherboard I use has seemingly increased in price by $100 due to scarcity. Enthusiast video card prices have also gotten crazy over the past couple of years so a high end video card is $100 more for top of the line in the consumer space.
    Reply
  • wallysb01 - Tuesday, September 09, 2014 - link

    Going to the E5 2699 isn’t needed. A pair of 2660 v3s is probably going to be nearly 2x as fast the 6376, especially for floating point where your 32 cores are more like 16 cores or for jobs that can’t use very many threads. True a pair of 2660s will be twice as expensive. On a total system it would add about $1.5K. We’ll have to wait for the workstation slanted view, but for an extra $1.5K, you’d probably have a workstation that’s much better at most tasks. Reply
  • Kevin G - Friday, September 12, 2014 - link

    Actually if you're aiming to double the performance of a dual Opteron 6376, two E5-2695v3's look to be a good pick for that target according to this review. A pair of those will set you pack $4848 which is more than what my complete system build cost.

    Processors are only one component. So while a dual Xeon E5-2695v3 system would be twice as fast, total system cost is also approaching double due to memory and motherboard pricing differences.
    Reply
  • Kahenraz - Monday, September 08, 2014 - link

    I'm running a 6376 server as well and, although I too yearn for improved single-threaded performance, I could actually afford to own this one. As delicious as these Intel processors are, they are not priced for us mere mortals.

    From a price/performance standpoint, I would still build another Opteron server unless I knew that single-threaded performance was critical.
    Reply
  • JDG1980 - Tuesday, September 09, 2014 - link

    The E5-2630 v3 is cheaper than the Opteron 6376 and I would be very surprised if it didn't offer better performance. Reply
  • Kahenraz - Tuesday, September 09, 2014 - link

    6376s can be had very cheaply on the second-hand market, especially bundled with a motherboard. Additionally, the E5-2630 v3 requires both a premium on the board and DDR4 memory.

    I'd wager you could still build an Opteron 6376 system for half or less.
    Reply
  • Kevin G - Tuesday, September 09, 2014 - link

    It'd only be fair to go with the second hand market for the E5-2630v3's but being new means they don't exist. :)

    Still going by new prices, an Opteron 6376 will be cheaper but roughly 33% from what I can tell. You're correct that the new Xeon's have a premium pricing on motherboards and DDR4 memory.
    Reply
  • LostAlone - Saturday, September 20, 2014 - link

    Given the difference in size between the two companies it's not really all that surprising though. Intel are ten times AMD's size, and I have to imagine that Intel's chip R&D department budget alone is bigger than the whole of AMD. And that is sad really, because I'm sure most of us were learning our computer science when AMD were setting the world on fire, so it's tough to see our young loves go off the rails. But Intel have the money to spend, and can pursue so many more potential avenues for improvement than AMD and that's what makes the difference. Reply

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