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Enabling HSA On The Kaveri APU

AMD A10-7850K And A8-7600: Kaveri Gives Us A Taste Of HSA
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Let’s get back to that concept of integration. Done right, integration should allow for compounding efficiencies. Subsystems brought closer together can communicate more quickly and save power.

Back when AMD introduced its Llano APU, the company put four Stars cores, a northbridge, two 64-bit memory channels, PCIe control, and a graphics engine on one die. It provided a 128-bit Fusion Control Link to the GPU for access to coherent memory space, simultaneously giving the CPU access to the GPU’s frame buffer. Separately, another bus gave the graphics engine higher-bandwidth access to memory.

The advent of Trinity (and then Richland) saw AMD push integration even further. It unified the CPU and graphics northbridges, doubling the data path bandwidth of its Radeon Memory Bus in the process. Perhaps even more significantly, it added an I/O memory management unit, attached through the Fusion Control Link, which gave the GPU access to virtual address space. The road to HSA was slowly being paved.

Kaveri incorporates a second bus through the IOMMU for coherency. It also exposes functionality called system-level atomics for synchronizing work across different cores. Together, those features complete the puzzle and enable a trio of HSA features.

A heterogeneous unified memory architecture, to begin, gives the CPU and GPU subsystems visibility into the entire memory space, up to 32 GB. Additionally, both the CPU and GPU are treated equally by AMD’s heterogeneous queuing model. Work can be dispatched from one to the other and vice versa. As a result, the APU’s on-die resources can tag-team more compute-intensive workloads.

Right off the bat, AMD is identifying a handful of tasks that’ll benefit from greater compute potential in the mobile and desktop spaces. Media playback is the first. You’ve already seen us demonstrate how demanding H.265 encoding can be. AMD is going to offload encode/decode onto the GPU, since it wasn’t able to build a fixed-function accelerator for playback in time, and doesn’t expect to even try encoding that way. Unfortunately, the requisite software is still being worked on, so we can’t compare CPU- to GPU-based HEVC playback today. In the same vein, video and image editing already do lean on GPU resources (we have our own Photoshop, Premiere Pro, and After Effects tests that are technically OpenCL-optimized). This will naturally continue with Kaveri. Of course, gaming is that killer app always able to push the latest and greatest; developers are already using compute in a variety of ways. For example, DICE uses a compute shader for tile-based deferred rendering in Battlefield 4.  

How Do I Use This HSA You Speak Of?

AMD makes a big deal about its effort to design hardware that just works within the scope of how developers write code today, rather than forcing them to change direction yet again. Leveraging HSA shouldn't have the long adoption curve of multi-core CPUs, which were difficult to fully utilize, or GPGPU computing, which was only possible through low-level APIs for quite a while. Instead, the company’s HSA features map to OpenCL 2.0, ratified late last year.

The bad news is that the applications already installed on your PC aren’t optimized for Kaveri’s full feature set (though AMD does claim legacy OpenCL benefits from HSA thanks to run-time improvements). That’ll require ISVs to gradually introduce updated software. But a growing swath of developers is becoming increasingly proficient with OpenCL, and we’ve already incorporated a number of workloads into our benchmark suite able to leverage the API. Though testing won’t reflect HSA-oriented design today, we’re already working with a couple of big names to fold in relevant workloads.

Bottom line: we waited years for the first mainstream OpenCL-optimized applications, and now we have many well-known multimedia, content creation, productivity, and gaming titles benefiting from heterogeneous computing. We only expect to be on-hold for months before software starts showing up written for OpenCL 2.0. When that happens, AMD’s HSA features should augment performance and power consumption in different ways.

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  • 13 Hide
    vertexx , January 16, 2014 5:30 AM
    While the gaming enthusiast may not have much here to get excited about, I think the real story here is the A8-7600. Especially at 45W, the numbers are quite impressive for this part.

    Of course, the other part of this story will be the adoption of HSA and Mantle. In this regard, I think AMD is playing its cards right. If you want to provide incentive for game developers to invest in developing for Mantle, that economic incentive is not going to come from providing a high-end part that tries to compete with high-end discrete GPUs. That economic incentive, and I believe it's huge, is in lowering the cost of entry to play your game.

    With the A8-7600, I believe AMD is providing a tremendous market opportunity and incentive if, with the combination of Kaveri plus embedded technologies (Mantle & True Audio), you can provide a playable gaming environment for the mass market. Admittedly, it may not be a "playable gaming environment" from an enthusiast standpoint, but as an entry point, it is quite good enough. It will be important for AMD to show that the release of Mantle for BF4 impacts performance for the Kaveri APUs in particular. More specifically, they will need to show that Mantle makes BF4 playable on a 7600. If they are successful in that regard, then I think they may really have something exciting here.

    I'm hoping AMD is successful in this, because it's obvious that the desktop CPU performance race has reached a point of diminishing returns. Kudus for AMD for potentially changing the game in the industry.

    All that said, they screwed up the pricing for the high-end. It needs to be $30 cheaper, and what is even the point of the 7700K? The 7850K at ~$145 and the 7600 where it is would have made much more sense if they want to incent adoption of this technology. The other point is they need to get motherboard manufacturers on-board with bringing more ITX FM2+ motherboards to market at different price points.
  • 11 Hide
    Someone Somewhere , January 16, 2014 4:23 AM
    Quote:
    A10-7850k is slower than A10-6800K ?? WTF.


    I got the opposite impression. Which graph are you looking at?
Other Comments
  • 0 Hide
    vipervoid1 , January 16, 2014 3:54 AM
    Somethings with Diagram u provided at page 9 ~ Core i5 4760k @@Please fix that ~
  • 1 Hide
    Someone Somewhere , January 16, 2014 4:10 AM
    Yeah, almost all the diagrams refer to the 4760K.

    Given that AM3+ looks like it's done, it would have been nice to see a 6-core chip. Still, one of these may end up in my next laptop.
  • 1 Hide
    cangelini , January 16, 2014 4:21 AM
    Will get the charts fixed shortly--thanks for the catch!
  • 11 Hide
    Someone Somewhere , January 16, 2014 4:23 AM
    Quote:
    A10-7850k is slower than A10-6800K ?? WTF.


    I got the opposite impression. Which graph are you looking at?
  • 8 Hide
    Jaroslav Jandek , January 16, 2014 4:24 AM
    Thank you for the article (especially the power consumption measurements), Chris. It is definitely an improvement over Richland but kind of boring (disappointingly expectable).

    I really like where AMD is going (HSA, GCN and TrueAudio).Too bad the manufacturing process of GlobalFoundries just can't match Intel's.

    Also, it would be interesting to see the new Bay Trail Pentium or Celeron CPUs (whichever is closer in performance) in the Efficiency graphs.
  • -1 Hide
    Someone Somewhere , January 16, 2014 4:25 AM
    I'm fairly sure that this is on TSMC's 28nm node. GlobalFoundries can't do that yet; this is on the same process used for AMD GPUs currently.
  • 0 Hide
    Jaroslav Jandek , January 16, 2014 4:45 AM
    Quote:
    I'm fairly sure that this is on TSMC's 28nm node. GlobalFoundries can't do that yet; this is on the same process used for AMD GPUs currently.

    28nm SHP from GlobalFoundries. AMD bought over $1 billion worth of wafers from them in december...

    I guess you have been reading the articles from a year ago about AMD still using TSMC despite promises of GlobalFoundries' new 28nm SHP process.
  • 9 Hide
    jacobian , January 16, 2014 5:12 AM
    I don't really believe into the whole HSA smoke-screen. By the time HSA-enabled apps take off, you will be ready to upgrade from your CPU again. The one terrible truth that stands out right now is that at current prices, the flagship Kaveri A10 doesn't make any sense whatsoever. Kaveri A8? Maybe. Richland A10-6790K? Perhaps. But the Kaveri A10 at $180 is a just a joke, specially after all that hype.
  • 3 Hide
    Someone Somewhere , January 16, 2014 5:16 AM
    CPUs are usually released at ridiculous prices, and come down over a month or two.
  • 13 Hide
    vertexx , January 16, 2014 5:30 AM
    While the gaming enthusiast may not have much here to get excited about, I think the real story here is the A8-7600. Especially at 45W, the numbers are quite impressive for this part.

    Of course, the other part of this story will be the adoption of HSA and Mantle. In this regard, I think AMD is playing its cards right. If you want to provide incentive for game developers to invest in developing for Mantle, that economic incentive is not going to come from providing a high-end part that tries to compete with high-end discrete GPUs. That economic incentive, and I believe it's huge, is in lowering the cost of entry to play your game.

    With the A8-7600, I believe AMD is providing a tremendous market opportunity and incentive if, with the combination of Kaveri plus embedded technologies (Mantle & True Audio), you can provide a playable gaming environment for the mass market. Admittedly, it may not be a "playable gaming environment" from an enthusiast standpoint, but as an entry point, it is quite good enough. It will be important for AMD to show that the release of Mantle for BF4 impacts performance for the Kaveri APUs in particular. More specifically, they will need to show that Mantle makes BF4 playable on a 7600. If they are successful in that regard, then I think they may really have something exciting here.

    I'm hoping AMD is successful in this, because it's obvious that the desktop CPU performance race has reached a point of diminishing returns. Kudus for AMD for potentially changing the game in the industry.

    All that said, they screwed up the pricing for the high-end. It needs to be $30 cheaper, and what is even the point of the 7700K? The 7850K at ~$145 and the 7600 where it is would have made much more sense if they want to incent adoption of this technology. The other point is they need to get motherboard manufacturers on-board with bringing more ITX FM2+ motherboards to market at different price points.
  • 1 Hide
    Au_equus , January 16, 2014 5:40 AM
    There appears to a typo or at least a contradiction on the table (first page), which lists the A10-7700K with 512 shaders. The paragraph below then says it has 384 shaders.
  • 3 Hide
    Nossy , January 16, 2014 5:40 AM
    Basically at this point it is not worth the premium $50-60USD or so over Richland and Trinity. At $180, you can get an i5 3570k at some places like Microcenter. Another disappointing release from AMD.
  • 0 Hide
    The_Trutherizer , January 16, 2014 5:51 AM
    I'm extremely excited to see the results from more HSA compliant apps myself. Some of the benchmarks I have seen are beastly.I'm really starting to think that the APU is a superior approach. With x86 performance past a certain point CPUs with traditional cores will be relegated to specialised servers in the eyes of consumers. I mean how quickly do you want to open an excel spreadsheet or encode or decode music and video? 0.5s or 0.3s?
  • 8 Hide
    nezzymighty , January 16, 2014 5:52 AM
    Quote:
    With the A8-7600, I believe AMD is providing a tremendous market opportunity and incentive if, with the combination of Kaveri plus embedded technologies (Mantle & True Audio), you can provide a playable gaming environment for the mass market. .... they may really have something exciting here.
    @ vertexx ... finally a non troll or die hard Intel/AMD fan that is making sensible points...I used to be a gamer and spent thousands, being a die hard fan of one today's chip makers. Now, as a mainstream user that has to use their money towards real life applications (rather than FPS) like a house, family, children, eating, paying bills, etc... I tend now to look for a solution to spend the disposable income on a solution that is cheap but encompasses the ability to do a little of everything...Well done AMD... please keep the innovation coming, and competition alive too keep prices down for all to enjoy...
  • 1 Hide
    rolli59 , January 16, 2014 5:54 AM
    Well if this is the future from AMD they are going to leave Intel alone in the high end gaming space.
  • -2 Hide
    styrkes , January 16, 2014 5:55 AM
    This measly increase in performance is just shoddy. Wonder what amazing story and hype AMD will put out for their next APU. I'm pretty much done with all this new advanced technology that's supposed to bring increased efficiency, performance, etc. etc. They've been doing this ever since they released their first APU. The next time AMD releases their next APU, I'll just jump straight into the benchmarks, see if that's any good.
  • -8 Hide
    styrkes , January 16, 2014 5:56 AM
    This measly increase in performance is just shoddy. Wonder what amazing story and hype AMD will put out for their next APU. I'm pretty much done with all this new advanced technology that's supposed to bring increased efficiency, performance, etc. etc. They've been doing this ever since they released their first APU. The next time AMD releases their next APU, I'll just jump straight into the benchmarks, see if that's any good.
  • 2 Hide
    Trachu , January 16, 2014 6:02 AM
    A8-7600 paired with R9-240 looks like a good deal. I belive this is a great Chance for AMD here if it sorts Crossfire performance things right Here lays the whole reason to buy APU instead of plain CPU.Why you have not commented about it in your final words when you thought about the alternatives?
  • 6 Hide
    logainofhades , January 16, 2014 6:32 AM
    Quote:
    Basically at this point it is not worth the premium $50-60USD or so over Richland and Trinity. At $180, you can get an i5 3570k at some places like Microcenter. Another disappointing release from AMD.


    Yesterday there was an HD7770 so low that you could get that and an FX 6300 for like $5 more than what newegg is asking for the 7850k. You can get an HD 7750 in that general price range with an FX 6300 now. In desktop, APU's still hold no appeal to me at all. Mobile, they have promise for sure.
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