While the readme does state this (could be) a joke, this unfortunately isn&#x27;t possible with PCI-e today:<p>Motherboards only support directly accessing a (up to) 256 MB segment of VRAM directly from the CPU. This is the BAR1 space&#x2F;aperture space.<p>So attempts to create allocations larger than that that are resident in VRAM but also accessible from the CPU will land in system memory, in order to ensure they are accessible from the CPU. Graphics drivers will either have the GPU read the data from system memory, or will do hidden copies to the GPU when they detect the resource is bound, etc.<p>The author sort of suspects this could be happening:<p>&quot;There is no guarantee that the persistently mapped buffer technique actually references video memory. The worst case it&#x27;s shadow memory and this actually wastes memory.&quot;