All your VRAM are belong to us

This is a maintenance release.

A few people have been reporting crashes and/or dramatic performance drops (down to 2-10 fps) with games like Watch Dogs: Legion and Horizon Zero Dawn Remastered, especially with Pimax headsets.

A sudden plunge to slideshow-range fps, with the game becoming unresponsive and possibly causing a driver timeout and reset (TDR event), which might even bring down the whole system with a BSoD... almost always all of that is triggered by the game wanting to allocate more video memory than your graphics card has.

This is called VRAM thrashing, and it's the result of bad programming. Windows offers a robust way for games to know at each moment how much VRAM your system has, how much of it is free, what is the maximum amount that can be reserved for the game, how many MBs the other applications in the system are using, and so on and so forth. Just by paying heed to that feedback mechanism, games could "play nice" and never become VRAM-devouring black holes into which your whole system gets sucked, orbiting slower and slower until only a reboot can restore normal operation.

But more and more frequently I have been seeing games just pretend that information doesn't exist, and happily go on allocating video memory in huge amounts that depend only from the resolution you're playing at and from static parameters like the texture quality you've chosen, completely disregarding the state of the system at runtime. Even the VRAM guard I implemented a few months ago gets defeated with this titles, as the engine just won't heed its recommendations.

This problem is made much more evident with VR mods (compared to playing in 2D) because the VR runtime itself needs a consistent amount of VRAM to function properly, and because we employ super-high resolutions that flat players don't usually need.

In particular with my mods, you might find that if you set the PPD slider to very high values, when you apply the new resolution the game immediately slows down to a crawl and you might even not be able to bring the slider back because the user interface is no longer responding.

Or, which is even more frustrating, if you have a powerful GPU and a wide-FOV headset like most Pimax models, the mod might try to resize the game on startup to a resolution which is already high enough to trigger VRAM thrashing, so you cannot even get into the game to dial down the PPD.

Release 24.1.0 of the R.E.A.L. VR mod implements two new safeguards to try and prevent this startup loop of death. First, no matter how powerful your GPU is, the mod will no longer attempt to automatically resize the game window to resolutions larger than 4096x4096 pixels upon launch. You can still select them once you're in game of course, for example by using the PPD slider for titles in which it is supported, but it will no longer happen before you can even gain control of the game. And second, the PPD value you choose when you apply a new custom resolution from the mod overlay will not be saved to disk immediately, but only after the game has been able to sustain a minimum of 30 fps for at least 5 seconds at the new resolution. This should avoid the pitfall where you select a resolution so high that the game starts VR thrashing, and you can't dial it down because the UI is unresponsive, but the value has already been persisted to the RealVR.ini file so the next time you launch the title it will immediately resize up and begin VRAM thrashing again.

Thank you for your logs and bug reports, and let's always keep the VR torch ablaze!!!