Performance issues with Lavapipe in Windows (?)

George Karpathios gkarpa1 at
Fri Apr 7 13:52:27 UTC 2023

Hi again, thank you Adam & Marek for your feedback! I appreciate it.

Unfortunately It's the same amount of time even if I skip the swapchain. I
have profiled some seconds of the execution using Visual Studio's profiler
(with the swapchain, normally) while panning an almost empty scene, and
it's identifying a hotpath. I have uploaded 2 screenshots of the call tree
at  if you'd like to check it out.

Another thing I'd like to note is that by using Mesa 23.1-dev (instead of
23.0.1) I got a nice performance boost of ~2-3x. However it's still
performing slower than what I'd expect on this system (right now it takes
60ms for 10 lines so I feel that something weird is still going on). Big
congratulations on your tremendous work anyway.

Best regards,

On Tue, Apr 4, 2023 at 9:24 PM Adam Jackson <ajax at> wrote:

> My first suspicion would be to rule out window system interaction. If you
> render to your own VkImage instead of to a swapchain, how fast can you go?
> - ajax
> On Tue, Apr 4, 2023 at 12:56 PM George Karpathios <gkarpa1 at>
> wrote:
>> Hi list, I hope all is well.
>> I would like to ask if there are any known issues regarding the
>> performance of Lavapipe in Windows 10.
>> I'm trying to add support for Vulkan software rendering into a relatively
>> large 3d modeling/rendering application, so I opted to try Mesa and
>> Lavapipe. I built LLVM 16.0.0 and Mesa 23.0.1 using the documentation
>> (thanks for that!). My environment is an 8-core Intel i7 (with an
>> integrated iGPU) with 32GiB RAM, an nVidia RTX 3070 and Visual Studio
>> 2019/MSVC.
>> The build procedure seems to be ok (Release builds, proper linking with
>> either MT or MD runtime libraries, proper DLL loading via VK_ICD_FILENAMES)
>> but the performance I'm getting during runtime is very slow. It looks like
>> it needs 1-1.5 seconds to render a virtually empty scene (think just a
>> floor grid of lines)  and over 15-20 seconds for a frame of a few thousand
>> vertices. The CPU utilisation also seems to be low, under 20-25%.
>> I understand that the information I provide is probably vague, but at
>> this point I just want to rule some probable causes out, like is there any
>> version of LLVM or Mesa or combination of them that is known to have such
>> issues? Maybe some build/installation configuration parameter or
>> environment variable that is important in Windows specifically and I may
>> have missed (I tried tweaking LP_NUM_THREADS but didn't change anything) ?
>> Anything that could point me in the right direction is highly valuable &
>> appreciated.
>> Also probably worth noting is the fact that the vkcube(pp) demo from the
>> Vulkan SDK seems to run ok with Lavapipe, but in this case I also notice
>> (in task manager) a ~50% utilization of the integrated iGPU (why?). In the
>> aforementioned larger application I don't notice any usage of the
>> integrated iGPU.
>> Any advice on what I could check/double check is more than welcome. Thank
>> you in advance for your time.
>> Best regards,
>> George
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