The use of multi-core technology to deliver more CPU horsepower is one of the increasingly common methods to providing higher system performance in hardware. This is true even for high volume consumer applications where cost and power can be very important. However, upgrading to a multi-core system doesn’t automatically guarantee performance improvements or an enhanced user experience. It’s not just a hardware problem – software must be written in a way that can make use of parallel hardware resources. But software is adapting – systems are getting much more complex, such that multiple processes and threads are running simultaneously in many cases, and applications are being written to take better advantage of multiprocessing hardware trends.
With that in mind, we recently used the BrowsingBench benchmark from EEMBC to evaluate the performance benefits of MIPS’ multi-core (MC) and multi-threading (MT) technologies. Our objective was to find out how these technologies enhance the user experience of a very popular and very real consumer application – web browsing on the Android software platform.
BrowsingBench is a credible and widely used tool that is trusted and cited by leading technology companies. It measures web page loading and rendering time for a large set of web pages with diverse content, and it does this in a reliable way which leads to repeatable and meaningful results. It will run on any connected device with a web browser. And rather than performing a synthetic test, BrowsingBench performs the same operations which a human would perform on the device. We’ve used several other benchmarks in the past that were suitable for evaluating MC/MT system performance; however none represented the real-world user experience on connected devices as well as BrowsingBench.
We ran BrowsingBench on a system based on the MIPS32® 1004K Coherent Processing System (CPS). In its maximum implementation, the 1004K CPS can support up to four cores and two hardware threads (also known as Virtual Processing Elements or VPEs) per core. To keep things simple for this test however, the configuration we used was dual core with two VPEs per core, for a total of 4 VPEs. VPEs are essentially logical CPUs that share one physical pipeline in each 1004K core, based on MIPS’ multi-threading technology.
The software platform running on our system was Android, and the web browser we used was the Android browser which comes with every Android-based system. To evaluate the benefits of multiple cores and VPEs on web browser performance, we ran BrowsingBench using the 4 different configurations listed in the table below. In all cases, the tests were executed on the same dual-core 1004K system; however we used the operating system to enable and disable cores and VPEs. The big question we wanted to answer was whether Android would be able to take advantage of these multiple processing resources to load and render web pages faster, thereby enhancing the user experience. To do that, Android would have to use parallel processes and threads while executing the browsing workload.
The results, which are shown in the table and chart below, leave no doubt: Android based web browsing performance is greatly enhanced by MC and MT technologies. The main observation is that browsing performance improves more than 2.5x when comparing the full configuration to the basic configuration. With a great deal of parallel execution under Android, the browser can truly benefit from the combination of MT and MC. A closer look at what’s happening under the hood in the Android system indeed shows that a lot of processes are running in parallel. The two main processes in the system are the Android Browser itself and another process called “system server,” which manages many components of Android including the display system, and is kept very busy during the BrowsingBench run.
Even if we limit the system to a single core, the MIPS MT technology gives us a BrowsingBench performance boost of 43 percent. One of the primary attributes of MT is to improve performance efficiency of a core, which it does by increasing the pipeline utilization of that core when multiple processes and/or threads are running. So for systems where silicon real estate is at a premium, choosing a multithreaded core can be a great way to boost system performance.
When multi-core and multi-threading systems were first introduced into the marketplace, most existing software was not optimized to make good use of these technologies. Today this is changing. Android is a complex software platform, and a perfect example of a high volume consumer platform that is quickly evolving and being optimized for optimal user experience in a Web-connected world.
At MIPS we are very pleased with the benchmark results because they demonstrate that our MC and MT technologies deliver much higher performance than the standard hardware used only a few years ago, and make a significant impact to end users of many connected devices from smart phones and tablets to connected DTVs.