The OnePlus 2 Reviewby Brandon Chester on December 14, 2015 8:00 AM EST
The OnePlus 2 uses Qualcomm's Snapdragon 810 SoC. At this point we've seen Snapdragon 810 in a number of devices and have an idea of what to expect. That being said, we've seen that performance can vary based on the device it's implemented in due to cooling and other factors like the CPU governor. On top of that, in many situations a device's performance is heavily dependent on the quality of its software in addition to the processing power of its SoC. For those reasons it's important to run the OnePlus 2 through our standard suite of web and native benchmarks in order to gauge its performance relative to other Snapdragon 810 smartphones, and the rest of the smartphone market as a whole.
There has been some concern online that these web browsing results may be inaccurate. The evidence to the contrary has been in the form of results from other reviews, results using other ROMs or kernels, or using other web browsers. To clarify, these scores were achieved using the latest version of Oxygen OS for the OnePlus 2, which is 2.1.2, in the latest version of Google Chrome. The reason for the scores is that OnePlus is specifically detecting whether or not Chrome is the active application, and if that is the case they unplug all of the Cortex A57 cores, regardless of the load being placed by both Chrome and background applications. Below I have embedded a video that demonstrates this behavior.
In this circumstance I launched a CPU load virus with 4 threads in order to cause Snapdragon 810's Cortex A57 cores to reach peak clocks. CPU4 through CPU7 represent the Cortex A57 cores, while CPU0 and CPU1 are two of the Cortex A53 cores, with the other two tracking at the same frequencies but not being shown on screen in order to accommodate my fingers. You can obviously see the clocks of the A57 cores dropping as heat becomes an issue, but that's not really the focus here. What is the focus is how all four cores shut off the moment Chrome is opened. This is clear evidence that OnePlus has hard coded this behavior. Whether or not it was introduced in more recent releases of Oxygen OS is hard to say, but given that users report achieving greater scores a few months ago this is very possible. It's also important to note that this behavior only affects Chrome, and results from the Chrome Dev or Chrome Beta channels are unaffected.
BaseMark OS II is a case where the Cortex A57 cores on the OnePlus 2 actually see some use, which translates into higher relative scores than what was achieved in browser testing. Improved scores in the graphics and NAND memory tests help make the overall score significantly higher than the OnePlus One. It's worth noting that the use of the Cortex A57 cores means that the BaseMark results may not be exactly representative of how the phone will actually perform in general use. For example, in this case the Cortex A57 cores are in use during the web test, while in general they never get used at all during web browsing, and in more intensive situations the best case is that there are two A57 cores in use at some frequency and the other two are shut off.
In PCMark the OnePlus 2 again does better in the web tests due to the fact that the A57 cores actually switch on, but falls behind in the photo editing test and even more so in the writing test. The writing test is actually a fairly good indicator of CPU performance, because it involves decompressing text files, moving text from one file to another, adding text and images, and then saving them to disk. During that entire period the A57 cores are not triggered at all, which contributes to the low score. Even with that, it's not exactly clear to me what additional factors make the Snapdragon 808 and 810 devices all perform so poorly here compared to a device like the Moto G which just has 4 Cortex A53 cores. It could very well be the result of issues with ART, or other problems with frequency scaling on the A53 cluster. In any case, like all Snapdragon 808 and 810 devices, the OnePlus 2 struggles in the aspects of the test that heavily tax the CPU.