README.md - renderers table - OpenGL columns to be next to each other

[Torinde]

Moved OpenGL version next to the OpenGL column. Clarified requirements column is for the Guest side. Added asterisk to "Note".

Further questions:

• Maybe just merge the OpenGL columns? e.g. if some OpenGL version is supported, then obviously OpenGL itself is supported
• The FPS column is very handy in illustrating what performance to expect. Can you share for what host CPU/GPU are those numbers? I assume CPU is relevant for softpipe/llvmlipe, GPU for SVGA3D.
• "Note for qemu-3dfx: performance depends on CPU emulation" - gives GPU host/guest performance ratios for KVM, Hyper-V, TCG accelerated, TCG full. But does it also matter how fast the host CPU is? E.g. I assume there's some lower boundary (e.g. a Pentium III host won't be very useful), but more importantly - are faster modern CPUs helping with performance or above certain level of host CPU the performance is flat?
• why llvmlipe stops at OpenGL 3.3? Mesamatrix shows 4.6
• why SVGA-II gen10 stops at OpenGL 4.1? clear, that's the maximum provided by VirtualBox

[JHRobotics]

Thanks for making the README file a little clearer to read :-)

Some answers:

• OpenGL itself is always supported, but if there no real OpenGL driver, Microsoft software renderer is used, but you usually don’t want this :-) Extra column indicate that OpenGL is reimplemented by driver.
• SoftGPU was developed on Intel i7-4770 + Nvidia GTX 1650 (performance like 10 years old gaming PC) and most testing is done on this configuration but I’m trying to test SoftGPU on every remarkable configuration. However, I usually get to mid-level office desktops, office laptops and entry level servers. CPU performance is also important for SVGA driver = you need very fast memory transmission between guest memory and host memory and host GPU. Newer CPUs are faster with this so if you have older CPU and few generations newer CPU with +- equivalent raw power, SoftGPU+SVGA with newer CPU will by faster. If is active vGPU9, GPU performance doesn’t matter, and integrated GPUs have same performance and dedicated. With vGPU10 performance of GPU does matter but when I tested the SoftGPU with an integrated Intel Xe GPU, the performance varied quite a bit depending on the driver version, so I would say that the quality of the DX12/Vulkan implementation also makes a big difference. But vGPU10 in VirtualBox isn’t fully complete and some features and commands isn’t working now, and performances may be differ in future versions.
• Yes, newer CPU technology makes difference – as I wrote above, virtual/virtualized GPU performance depends on how fast are guest-to-host memory transactions (bandwidth, latency). After it, you also need transfer it from memory to GPU, so PCI-e bus speed and memory (system and video memory) also matter.
• OpenGL version is limited by build-in GLSL version, which is currently 3.30 (softpipe column in Mesamatrix). It is possible to use higher GLSL compiler, but it requires additional libs and newer LLVM. It is all possible, but work seems pointless to me, because OpenGL 3.3 is enough to run all 98-era application and games. For SVGA driver is OpenGL version is also determined by number of features which has driver and virtual HW. Currently is downgraded to 3.3 too (I’ll update the information in readme), because some features in VirtualBox don’t working.

PS: I enabled discussions so you can also ask here, I know that my answers have quite high latency, but I will try to improve myself.

[Torinde]

Thanks for the information!

• "Note for qemu-3dfx" - OK, so I assume the ratios currently given are for i7-4770 + GTX1650?
• OpenGL 3.3 - agree that's probably sufficient for Win9x. Maybe if you add WinXP support, then it will be useful option to have OpenGL 4.x (is Vulkan utilized on XP?)

[JHRobotics]

“i7-4770 + GTX1650”: SoftGPU born here, so, yes assume it as benchmark low level.

And with current LLVM (18.1.8) is OpenGL now in version 4.5, also after I fixed registry range in SVGA driver, now is available OpenGL 4.1 in VirtualBox and OpenGL 4.3 in VMware (only with Mesa 24.x). But one thing bit scares me – DLL is now pretty HUGE: ~75 MB with stripped debug symbols. It is currenly useful only for Nine, because with higher shader model Nine works better.

Vulkan in probably out of XP time, even if would work there (Mesa + Lavapipe in theory can) there’s no way how utilize it.