Wine Code Merged To Overcome A Vulkan Performance Penalty

Merged this week ahead of the Wine 9.4 development release due out next Friday is support for using the new Vulkan VK_EXT_map_memory_placed extension to overcome a performance penalty with Windows on Windows 64-bit (WOW64) for games/apps.

As mentioned in mid-February when Vulkan 1.3.278 was released with the VK_EXT_map_memory_placed extension, this new capability will help out Wine / Steam Play. The extension devised by Valve, AMD, NVIDIA, Collabora, and CodeWeavers was worked on with Wine on the mind. VK_EXT_map_memory_placed allows requesting a memory map be placed at a particular virtual address. This was requested by Wine developers to better support 32-bit Windows applications while using 64-bit Vulkan drivers. If a 64-bit Vulkan driver returns a pointer from vkMapMemory that the 32-bit API consumer can't deal with due to being out of the 32-bit range, there are problems. But by leveraging VK_EXT_map_memory_placed to ensure memory objects are in an acceptable range, the 32-bit Windows software on Wine can be dealt with so that the memory objects won't be outside the 32-bit range.

The merge request for using VK_EXT_map_memory_placed for memory mappings on WOW64 was merged this week and will be found in Wine 9.4 next Friday. That merge request explains:

"With the new extension, we may implement wow64 correctly, without VK_EXT_external_memory_host hacks. This is both more correct and more performant (essentially eliminating Vulkan wow64 performance penalty)."

The NVIDIA Vulkan beta driver already supports VK_EXT_map_memory_placed while RADV support was merged this past Friday. The NVK support for this extension is also found in Mesa 24.1-devel while so far I haven't seen any Intel ANV Vulkan driver patches for VK_EXT_map_memory_placed.