My week with Dell Venue 8, the first Android tablet to use a PowerVR Rogue GPU

Intel® Atom™ processor Z3460/Z3480 supports OpenGL ES 3.0 and OpenCL 1.2 out of the box

Alexandru Voica contributes to ‘My week with’, a column covering consumer products that use IP technologies from Imagination.

When Intel first announced the new Atom Z3460/Z3480 (Merrifield) processors back in February, I was curious to find out the list of OEM partners which would launch the first devices to include these innovative chips.

Among the companies mentioned were Asus, Dell and Lenovo, all leading brands that have a tradition of producing affordable yet premium-looking hardware. I was therefore very happy to find out that since early July, consumers in the UK and US can get their hands on a brand new Dell Venue tablet.

Product design and hardware specifications

The refreshed Venue range of Android tablets from Dell is based on Intel Atom processors that run Android 4.4 KitKat. For those of you who aren’t familiar with the new Intel Atom Z3460/Z3480 processors, head over to AnandTech for a comprehensive review of their features and performance. Essentially, the Atom Z3460/Z3480 SoCs are 64-bit apps processors that include a dual-core CPU based on the Silvermont architecture and a quad-cluster PowerVR G6400 GPU capable of OpenGL® ES 3.1, OpenCL™ 1.2 and RenderScript.

Dell Venue 8 - Intel Atom - PowerVR G6400 - OpenGL ES 3_0 OpenCL (1)Dell Venue 8 comes in a simple, fuss-free package

Both devices are lightweight, powerful and stylish tablets designed to entertain with high-resolution touchscreens and award-winning audio. Since the new Venue 8” tablet is less than 9 mm thin and weighs 370 gr (0.82 pounds for my American friends), I found it easy to hold and carry around the office. The back has a textured plastic cover so grip is greatly improved.

Additional specifications include a Full HD screen, high-speed 802.11ac and low-power Bluetooth 4.0 connectivity, 16 GB of internal storage, and a micro SD card slot for up to 64 GB of extra storage.

GPU performance

I am going to dedicate the larger part of this article to graphics performance since this device is among the first Android tablets to ship with a PowerVR Rogue GPU.

OpenGL ES 3.0 and graphics performance

PowerVR Rogue GPUs recently achieved OpenGL ES 3.1 conformance; this new API is set to be supported on devices running the upcoming Android L operating system. You can read more about the new OpenGL ES 3.1 API on our blog and see a quick demo of Rogue GPUs using compute shaders for image processing.

The PowerVR G6400 GPU inside the Dell Venue 8 tablet is a high performance, area-optimized graphics processor which includes four shading clusters and 128 ALU cores; at a peak frequency of 533 MHz, G6400 can deliver up to 136.44 GFLOPS. Since Android 4.4 supports OpenGL ES 3.0, I’ve loaded Soft Kitty and I was really impressed to see that the demo never drops below 35 fps! For a sequence that includes up to 200,000 triangles, this is really amazing performance from a device that costs only £179.

Dell Venue 8 - Intel Atom - PowerVR G6400 - OpenGL ES 3_0 OpenCL (1)Our Soft Kitty OpenGL ES 3.0 demo running at Full HD resolution

Thanks to our high performance, efficient GPU architecture, the tablet achieves impressive results across multiple graphics benchmarks, including GFXBench 3.0, Basemark X 1.1 and 3DMark. In the chart below, I’ve added four Android devices for a quick comparison of 1080p offscreen GPU performance using GFXBench from Kishonti.

Dell Venue 8 - Intel Atom - PowerVR G6400 - Graphics performance comparisonBoth Dell Venue tablets stack up very well against mid-range and high-end devices

An important element to remember here is that two of the devices above retail for more than double the price of the Venue 8. The new Dell Venue tablets really deliver a lot of bang for their buck, offering consumers a high-performance, quad-cluster PowerVR GPU at a price point typical for an entry-level device.

Dell Venue 8 comes pre-bundled with OpenCL and RenderScript

From the chart above, you can see that PowerVR Rogue GPUs perform admirably when crunching through graphics tasks; however, these processors can be used for compute too. Running image and video processing at Full HD resolutions on a mobile device clearly requires a power efficient GPU since smartphones and tablets can become severely limited by the thermal envelope set by DVFS.

In the past OpenCL had only been available on developer boards but the Venue 8 tablet is the first consumer device to come with both OpenCL and RenderScript working out of the box. I’ve loaded our OpenCL Camera Adjustment image processing demo to offer you a quick comparison in performance.

Dell Venue 8 - Intel Atom - PowerVR G6400 - OpenGL ES 3_0 OpenCL (2)The new Dell Venue 8 tablet runs OpenCL out of the box

When running on our PowerVR G6400 GPU, the image processing demo averages around 74 fps while the Intel CPU peaks at 12 FPS. To put this into perspective, an Exynos-based Samsung Galaxy S4 using a PowerVR SGX544MP3 GPU was able to run the same demo at roughly 27 FPS.

Since the PowerVR GPU is clocked at a much lower frequency than the CPU, running these OpenCL kernels on the graphics processor not only improves performance dramatically but also saves considerable power – therefore preventing extreme overheating and rapid battery drain.

Furthermore, all Rogue GPUs have been designed for efficient GPU compute, featuring separate data paths that have been optimized for low-power compute and improved support for local memory .

Dell Venue 8 - Intel Atom - PowerVR G6400 - OpenGL ES 3_0 OpenCL (5)

The Camera Adjustment OpenCL app has multiple filters you can play with, including sepia, fisheye, saturation, watercolor, edge detect, Gaussian blur or chroma key

Dell Venue 8 - Intel Atom - PowerVR G6400 - OpenGL ES 3_0 OpenCL (2) Dell Venue 8 - Intel Atom - PowerVR G6400 - OpenGL ES 3_0 OpenCL (4)
Dell Venue 8 - Intel Atom - PowerVR G6400 - OpenGL ES 3_0 OpenCL (6) Dell Venue 8 - Intel Atom - PowerVR G6400 - OpenGL ES 3_0 OpenCL (7)

Running the compute kernels on the PowerVR G6400 GPU vs. the main CPU results in a 6x performance boost

If you are developer interested in experimenting with OpenCL on PowerVR, we will soon be releasing our Early Access Programme for PowerVR Rogue; until then, you can download our PowerVR Rogue OpenCL programmer’s reference manual and our OpenCL real-time Camera Adjustment app – both are subject to a click-through NDA.

For our readers in the US, Dell is currently selling the Venue 7 tablet for only $159.99, whereas the Dell Venue 8 can be acquired for $179.99. If you live in Great Britain, you can buy a new Dell Venue 8 tablet from the company’s UK website – prices start at £179.

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  • LM

    Is it not bit low if you compare it with the new tablet Nvidia Shield?
    Cheers
    LM

  • http://withimagination.imgtec.com/index.php/author/alexvoica Alexandru Voica

    I think we should keep things in perspective. The device you mention is a premium tablet designed for gaming and priced accordingly. The Dell Venue range starts at $159.99 but still has the GPU performance of a high-end device.

    Speaking of ultra-high end GPUs for mobile, I’ve already covered the topic in the article below

    http://blog.imgtec.com/powervr/powervr-gx6650-redefining-performance-mobile-192-cores

    Regards,
    Alex.

  • tangey

    Alex, Was the chip inside your dell a 3460 or 3480 ? According to Intel the 3460 GPU maxs out around 460Mhz ?

    focusing on the performance, I am disappointed with the scores being achieved by the moorefield variant of this tablet on Glbench tests. It is quite a distance behind the class leading tablet that has been out for around a year at this time, which uses the similar GPU but clocked significantly slower ? It is even being outperformed by A80 (G6230) devices, and even allowing for the fact that A80 clocks in excess of 700Mhz, the G6430 should be beating it @533Mhz.

    Do you have any guidance on why the intel implementation appears to be underperforming in a relative sense ?

  • http://withimagination.imgtec.com/index.php/author/alexvoica Alexandru Voica

    I have been using a Dell Venue 8 (Intel Atom Z3480) to run OpenGL ES 3.0 and OpenCL apps. This SoC has a PowerVR GPU clocked at a base frequency of 457 MHz (533 MHz in burst mode).
    Dell Venue 7 has an Atom Z3460 where the GPU is clocked at 400MHz (burst frequency is 457 MHz); this is what we’ve used for the benchmark comparison.

    Both devices have only 1GB of LPDDR3 memory (this is one of the reasons for the low price tag); I can understand how it might be hard to understand how a dual-cluster G6230 matches a G6400, but these tests can be heavily influenced by DVFS and memory controller/bandwidth performance. Additionally, if you read my post on Rogue GPU specs

    http://blog.imgtec.com/powervr/the-complete-guide-to-powervr-rogue-gpus-specifications-features-api-support

    you will notice that G6x30 GPUs have low-power FP16 ALUs which directly influence rendering performance, including in apps such as benchmarks.

    These tablets have extremely good compute performance (more ALUs) so that is why I think they make good OpenCL platforms. When it comes to resolution-intensive apps, this is where memory limitations (size, single vs dual-channel, etc.) come into play.

    I think the best way to look at the results is from a “this is what the GPU can do given SoC specs” perspective. I still believe they are very good platforms given their price points – I have been using them around the office as my work tablets and I was very pleased with the overall performance.

    Regards,
    Alex.

  • LM

    Thanks Alex, it makes a lot of sense. I look fwd to see the big brother GX6650 in some devices. Even though it will appear only in expensive devices.
    Thanks
    LM

  • LM

    Hi Alex, I’ve seen the benchmark of Nvidia Shield. They are pretty impressive. You are right saying we need to compare it with the high end counter part of Series 6. Nevertheless at the moment and for the near future there is not many SOCS around that can have same performance GPU wise. All the current tablets and I believe also the ones that we will see by end of this year won’t have the high specs GX6650.
    Cheers for now
    LM

  • ray_94

    When the 3G version of this tablet will be available?

  • DrFrito

    I understand your main focus on the power, however I’m curious about the wifi performance as this comes with the new AC standard. Did you even notice a difference vs N? Thanks

  • http://withimagination.imgtec.com/index.php/author/alexvoica Alexandru Voica

    Hi,

    We’ve been using the tablet for our FlowCloud (http://www.imgtec.com/flowcloud) demos too and Wi-Fi has been working very well. Can’t wait to try one of those Dell Venue 8 7000 Series too!
    http://en.community.dell.com/dell-blogs/direct2dell/b/direct2dell/archive/2014/09/11/icymi-world-s-thinnest-tablet-revealed-by-michael-dell-at-idf

    Regards,
    Alex.