Microsoft’s Windows 10 is still trucking on with all the user improvements and new features planned for the Creators Update, and one of those is Game Mode, a new feature designed to improve the performance of games running on Windows 10. Game Mode is an optional feature that allows you to prioritise processor cores to focus on gaming workloads, leaving the remaining cores to run the OS and any background processes.
This, as I suggested in a previous article, could lead to some interesting scenarios where users can have an intensive program like Blender running in the background while a game runs in the foreground, unaffected by Blender’s load because it’s being properly prioritised. Microsoft has now confirmed that Game Mode doesn’t just prioritise games for performance, it also completely reserves cores for games as well.
At GDC 2017, Xbox Advanced Technology Group’s Eric Walston explained to developers how Game Mode actually functions. Walston explained that Windows typically sees a game as just another process that has priority, which means that like other processes running in the background, games have to vie for resources to run on your hardware. If you turn on Game Mode for a UWP game from the Windows Store, or any Win32 title from services like Steam and Origin, Game Mode will actually remove processes from being run on specific cores and dedicate the game to only run on those reserved cores, thereby increasing performance.
This way, there’s no contention between threads, there are no hiccups and stalls from running all the background processes at the same time. In a machine with eight cores, Game Mode will reserve up to six of those depending on what other processes are consuming power, and it’ll completely stop any thread hopping on the reserved cores.
It gets better. In my previous article I mused that this benefit might not stretch to the GPU as well, because foreground applications usually take up the most processing power on the GPU. Well, Walston went on to explain that Game Mode takes this even further, sucking up even more GPU cycles to be used by the game currently running, and reserving more GPU memory for the game. Somehow, Windows isn’t affected by this at all, which is quite surprising, given that UWP games are typically run in windowed fullscreen mode to allow you to use the Xbox overlay and alt-tab out of the game easily, but the GPU still dedicates horsepower to running the OS in the background.
Finally, developers will be able to check a flag in the registry to determine if Game Mode is turned off or on for a particular application. They’ll then have an option to force Game Mode, if desired, or keep it turned off and warn the user that it isn’t running optimally. Having Game Mode on might not be the best thing for all PCs, because not everyone will have a Core i7 or Ryzen 7 processor in their system.
What does this mean for Ryzen?
AMD’s new Ryzen family of processors has suffered a few hiccups during its launch because of issues with Windows – everything from the scheduler swapping threads to cores that shouldn’t be running, to Windows power management not liking fractional multipliers, to background processes taking control when they shouldn’t be. Game Mode could help a lot here because applications will end up pegged to a set of cores that won’t change, and Ryzen has a bandwidth issue when swapping workloads between two cores on different CCX modules. In some reviews online, there is some evidence to suggest that manually setting a program’s affinity to a certain number of cores helps with performance, but this would be the first time that an application on Windows will see total, complete control of one or more cores.
This may also, in time, see improvements for the Bulldozer family as well. Bulldozer shares the same woes as Ryzen when it comes to thread contention, because it shares a lot of hardware between cores, and this creates bottlenecks when you’re not able to manage what other processes are running on those cores. Bulldozer and Piledriver continue to see performance improvements from multi-threaded games that are now multi-core aware, so you might be able to squeeze more life out of your system with this upcoming update while you save up for a Ryzen 5 or 7 processor.
The Windows 10 Creators Update is free to download for everyone running a fully patched Windows 10 installation, and is expected to become available via a staggered rollout to users beginning in April 2017.