MediaTek announced a quad-core system-on-chip with dual ARM Cortex-A15 and dual Cortex-A7 cores that is said to be the first Big.Little SoC to operate all four cores simultaneously. The tablet-focused MT8135 is further equipped with a new PowerVR Series6 G6200 GPU from Imagination Technologies, and will be followed by an eight-core “True Octa-Core” Big.Little SoC with similar heterogeneous multi-processing capabilities.
MediaTek’s quad-core MT8135 is only the second SoC to use ARM’s hybrid Big.Little architecture, which load balances faster and slower cores in the same SoC for greater situational power-savings. On July 27, several days before the SoC was unveiled, Samsung also announced it was working on an eight-core Big.Little model called the True Octa-Core, although it offered few details (see farther below).
Unlike the True Octa-Core and the eight-core Samsung Exynos 5 Octa 5410, the initial MT8135 device uses only four cores — two fast Cortex-A15 cores and two slower, more power-efficient Cortex-A7 cores. However, unlike the Exynos 5410 or the newly updated Exynos 5420, it supports heterogeneous multi-processing (HM), enabling all cores in a Big.Little SoC to operate simultaneously for peak performance.
MediaTek’s Big.Little heterogeneous multi-processing model
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The HM capability is said to be the result of an “advanced scheduler algorithm, combined with adaptive thermal and interactive power management to maximize the performance and energy efficiency benefits,” says MediaTek. As a result, the SoC can be optimized for performance, as well as power efficiency. Although MediaTek makes no mention of it, the scheduler algorithm would appear to be enabled by a new HM-enabling Global Task Scheduler (GTS) profile introduced recently by ARM and Linaro. GTS can also improve switching performance and increase battery life, while enabling non-symmetrical Big.Little core configurations, according to Linaro.
The MT8135 appears to be based on the quad-core Cortex-A7 based MT8125, which has appeared in Android devices such as the Lenovo’s IdeaTab S6000. Like that SoC, it offers MediaTek’s homegrown 4-in-1 connectivity chip, which integrates WiFi, Bluetooth 4.0, GPS and FM functions. The MT8135 also supports WiFi certified Miracast technology for streaming multimedia content between devices.
ARM Cortex-A7 and -A15 core diagrams
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In addition to swapping out two of the four Cortex-A7 cores for two faster Cortex-A15 cores, the MT8135 also exchanges the earlier PowerVR Series5XT graphics processing unit (GPU) for a much faster Imagination Technologies PowerVR Series 6 G6200 (diagram below). This is the first of several SoCs that will be introduced this year with the PowerVR Series 6, says Imagination.
Imagination Technologies PowerVR G6200 GPU diagram
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The PowerVR Series 6 GPUs offer an improved tile based deferred rendering (TBDR) architecture implemented on universal scalable clusters (USC), says Imagination. The GPU also adds high-efficiency compression technologies, including lossless geometry and PVRTC/PVRTC2 texture compression, for reducing memory bandwidth requirements. Other touted features include scalar processing for improving ALU utilization and easing programming.
The PowerVR G6200 GPU delivers up to four times more ALU horsepower compared to the PowerVR Series5XT, claims Imagination. In addition, it supports graphics APIs including OpenGL ES 1.1, 2.0 and 3.0, OpenGL 3.x, 4.x and DirectX 10_1, as well as programming interfaces such as OpenCL 1.x, Renderscript, and Filterscript.
In the Exynos 5410 SoC, Samsung used a Series5XT variant called the PowerVR SGX544MP3 GPU. However, it switched to an ARM Mali-T628 MP6 GPU in the 5420, claiming it provides twice the graphics performance.
According to Laptop, MediaTek clocks the two Cortex-A15 cores in the MT8135 at 1.5GHz, and the two –A7 cores at 1.2GHz. By contrast, the latest, Mali-enhanced Exynos 5420 bumps up the -A15 cores 1.6GHz to 1.8GHz, and the -A7 cores from 1.2GHz to 1.3GHz.
Laptop benchmarks of a MT8135 reference platform showed that the device was narrowly beat out by the U.S. version of the Samsung Galaxy S 4, which runs a quad-core, 1.9GHz Cortex-A9 based Qualcomm Snapdragon 600. However, it pulled ahead of the HTC One (1.7GHz Snapdragon 600) and the seven other high-end Android devices in the comparison.
True Octa-Core takes on Samsung’s Octa
On July 27, MediaTek unveiled a “True Octa-Core” Big.Little SoC that goes head to head with the Exynos 5 Octa processors. MediaTek was short on specifics, but posted background materials and a white paper. MediaTek touts the SoC’s heterogeneous multi-processing prowess, which appears to be even more advanced to that of the quad-core MT8135.
The True Octa-Core offers advanced multi-threaded programming that enables different sequences to be allocated to different cores, “delivering enhanced video frame-rate processing and exceptionally low-latency gaming experiences,” says MediaTek. The architecture offers “the unique ability” to allocate individual browser tabs to CPU cores, and it can also delegate user inputs to individual cores and render 3D graphics effects more smoothly, says the company.
In decoding HEVC (H.265) FHD video, battery use can be reduced by up to 18 percent compared to current quad-core processors, claims MediaTek. In display mode, the SoC is said to provide 20 percent more frames.
MediaTek’s quad-core SoCs have been used in 350 projects and over 150 mobile device models since the MT6589, a smartphone-focused Cortex-A7 based SoC launched last December, claims the company.
“The MT8135 is the first implementation of ARM’s big.LITTLE architecture to offer simultaneous heterogeneous multi-processing. As such, MediaTek is taking the lead to improve battery life in next-generation tablet and mobile device designs by providing more flexibility to match tasks with the right-size core for better computational, graphical and multimedia performance,” stated Mike Demler, Senior Analyst with The Linley Group.
“Thanks to our PowerVR Series6 GPU, we believe the MT8135 will deliver five-times or more the GPU-compute-performance of the previous generation of tablet processors,” stated Tony King-Smith, EVP of marketing, Imagination Technologies.