Hardware Overview and System Performance

The Xiaomi Redmi Pro uses MediaTek’s two most powerful SoCs depending on the configuration you opt for. Here’s a quick breakdown of the Redmi Pro line:

  • Exclusive Edition – MediaTek Helio X25 – 4 GB of RAM – 128 GB storage
  • High Edition – MediaTek Helio X25 – 3 GB of RAM – 64 GB storage
  • Standard Edition – MediaTek Helio X20 – 3 GB of RAM – 32 GB storage – Reviewed

The Helio X20 and Helio X25 are very similar SoCs, only differing slightly on clock speeds. Both SoCs are deca-core designs with three clusters of CPU cores: the first cluster is a dual-core ARM Cortex-A72 configuration for high-performance workloads; the second is a quad-core Cortex-A53 for medium workloads; and the third is another quad-core Cortex-A53 for low power tasks.

This design differs from the usual big.LITTLE configuration through the addition of that third medium-power quad-core cluster. It’s an interesting solution to what MediaTek believes is a problem with high-end SoC design, and it allows their Helio X20 and X25 SoCs to have “more gears” and “better fuel efficiency.”

The only major difference in the CPU between the X20 and X25 is the clock speed of the high-performance Cortex-A72 cluster. In the X25, the A72s are clocked up to 2.5 GHz. In the X20, MediaTek specifies a clock speed for the A72s up to 2.3 GHz, although in the Standard Edition Redmi Pro, Xiaomi has underclocked this cluster to 2.1 GHz.

The other two quad-core A53 clusters use the same clock speed across all variants. The low-power quartet is clocked at 1.4 GHz, while the medium power cluster is rated up to 2.0 GHz. In the Redmi Pro, I never saw the medium power cluster exceed 1.8 GHz.

The Helio X20 and X25 compete directly with the Qualcomm Snapdragon 650, which uses a similar CPU design except without the medium-power cluster of Cortex-A53 cores. MediaTek does have a process node advantage here, as the X20/X25 are built on a 20nm process, whereas the Snapdragon 650 is still on 28nm.

As for the GPU, we’re looking at an ARM Mali-T880 MP4 clocked at either 700 MHz (Helio X20) or 850 MHz (Helio X25). This is a similar GPU configuration to HiSilicon’s Kirin 955 seen in the Huawei P9, albeit at a lower clock speed. The Mali-T880 is also used in the Samsung Exynos 8890, as seen in the Samsung Galaxy S7, although Samsung opted for a 12-core (MP12) variant.

The review unit I received is the Standard Edition, so in the benchmarks below we’re looking at the slowest Redmi Pro variant on the market. Opting for the more expensive models should provide a small performance increase.

Bizarrely, the Redmi Pro only supports Wi-Fi 802.11b/g/n on just the 2.4 GHz band; there’s no support for Wi-Fi ac or 5 GHz networks, which is disappointing. There’s also Bluetooth 4.2 support, A-GNSS+BDS, infrared for controlling multimedia devices, and up to Category 6 LTE on bands most suitable for use in Europe and Asia. There’s no NFC support in this device.

The performance of the Redmi Pro in general applications is very interesting. While the Helio X20 is nearly the fastest chip MediaTek has to offer, and it certainly rivals the Snapdragon 650 on paper, the Redmi Pro just doesn’t feel that fast to use. Don’t get me wrong, the Redmi Pro is not slow per se, but the Snapdragon 650 devices I’ve used so far seem to have a noticeable edge over the Redmi Pro.

I noticed two main issues with the Redmi Pro during usage: input lag while typing on the keyboard, and slow app loading. General performance within apps seems fine, however the keyboard occasionally fails to keep up with my touchscreen inputs, which is always annoying and points to a CPU issue. Slow app loading is almost always the product of slow storage, which I’ll examine later.

The benchmarks here paint some interesting pictures. Running a variety of tests in Google Chrome, our browser of choice for Android, shows the Helio X20 falling well behind the Snapdragon 650 to the point where Qualcomm’s silicon is more than twice as fast. In real-world usage this leads to noticeably worse performance in the Redmi Pro’s web browser.

Having examined the data closely, it appears as though the inclusion of a third quad-core Cortex-A53 cluster actually hinders the performance compared to a more traditional dual cluster solution. Rather than switching from the low-power A53s during idle to the performance A72 cores during intense web browsing, the Redmi Pro simply bumps tasks to the medium-power A53 cluster. This is in contrast to the hexa-core Snapdragon 650, which sees web browsing transition smoothly to its A72 cores.

My guess is there is a driver issue with the MediaTek Helio X20 and Google Chrome that is hindering performance. This is disappointing considering there are no such issues with Qualcomm’s competing SoCs.

Aside from in Chrome, the Cortex-A72 cores are used for high-performance tasks on a reasonably frequent basis. In our other benchmarks, the Snapdragon 650 boasted just single digit performance gains over the Helio X20, which is actually a reasonable result for Qualcomm considering the Helio X20 uses higher clock speeds. It also shows that the addition of four medium-power A53 cores does nothing to improve performance, as most real-world workloads will never use ten cores simultaneously, and rarely use more than four at a time.