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Mobile Platform Results And Wrap-Up

OpenCL In Action: Post-Processing Apps, Accelerated

In looking at these notebooks, we need to answer two questions. First, are the integrated graphics engines on low-power mobile processors fast enough to accelerate a compute-oriented workload? Second, how do AMD's mobile APUs compare to its desktop implementations?

First let’s compare the Gateway machine running an A8-3500M to the desktop A8-3850. Statistically, the two are almost in a dead heat, which is pretty phenomenal when you consider that the A8-3500M is a 35 W part standing up to the 100 W A8-3850.

While 480p video gets handled in real-time on both platforms, slower core and graphics clocks catch up to the notebook. It takes a hit on the 1080p test, losing one-third of its frame rate.

When we crank up the vReveal load to six effects, the system's CPU utilization tops out in the 80-85% range with software-based rendering. The A8 APU also vacillates between 26 and 32% with GPU acceleration turned on, suggesting that this platform is again being topped out based on the way it distributes CPU- and GPU-specific work.

In this demanding application, the Gateway notebook still manages to cope with 480p video in real-time (100%). Also impressive is that, in the 1080p benchmark, the mobile APU only takes a 5% hit compared to the desktop A8-3850. Although 24% of real-time seems pretty grim next to the Radeon HD 5870's ability to achieve 67% of real-time performance in this test, the fact that we're comparing a 35 W part to a 100 W APU and 188 W graphics card working cooperatively speaks volumes, too.

Finally, let's check to see how the APU fares against Intel's Sandy Bridge-based architecture with HD Graphics 3000. Of course, all of the tests are run in software mode, so we're only gauging performance without OpenCL-based acceleration.

With 1080p unaccelerated video processing, the APU-powered machine was pushed to 69% utilization with one effect and 85% with six. Here, we see 70% and 84%, respectively.

Nevertheless, Intel's mobile Core i5 is able to post decent numbers. With one effect applied to the 480p sample, it manages real-time playback. With six, it falls to 75% of real-time. Unassisted, AMD's APU was only able to hit 40% of real-time in the same test. The thing is, collaborating with its 400 Radeon cores, the A8 jumps back up to real-time rendering.

Those results are exacerbated at 1080p. In a CPU-to-CPU comparison, Intel doubles AMD's performance. But once you get the GPU acceleration involved, the APU assumes a definite lead.

Learning Lessons

After all of that, what do we come away with?

  1. When time is money, there is no substitute for high-end hardware, and discrete components remain important upgrades for enthusiasts. None of the configurations we tested could touch our FX-8150 and Radeon HD 7970 working together. Had this comparison involved even pricier processors, we probably could have predicted the outcome of the software-only tests. In any case, balance remains a critical component in picking the hardware for your next upgrade.
  2. When budget is a concern, getting general-purpose and graphics resources on the same piece of silicon can facilitate notable performance boosts in applications optimized to capitalize. Yes, a mid-range discrete graphics adapter will outperform as a result of its more extensive architecture. However, the APU design gets you in on the ground floor of GPU acceleration without requiring an add-on graphics card (with its corresponding expense). APUs most certainly won't satiate enthusiasts accustomed to powerful discrete adapters, but they do put a much-needed emphasis on capable integrated functionality where previous chipset- and processor-based engines came up short.
  3. The benefits of a mobile APU can be close to equivalent to a desktop APU, again, in the right application. There's a reason the desktop A8-3850 has a 100 W TDP and the mobile A8-3500M is constrained to 35 W. However, there's also something to be said for an intelligent balance between processing power and graphics muscle to help notebooks yield a better overall experience.

In all honesty, this is the most exciting development we’ve seen from AMD in quite a while, and it deserves more attention. Stay tuned for our next installment on gaming acceleration in a few weeks, and we’ll see if similar (or better!) results can be enjoyed there, as well.

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