UE4's Vulkan backend uses vkCmdWriteTimestamp with TOP_OF_PIPE
to measure how long a workload took in the GPU Benchmark. This is wrong
and writes the timestamp before the workload is actually finished,
making it seem like the GPU is much faster than it actually is.
This caused subsequent benchmark passes to contain way too big workloads,
which caused soft hangs on slower GPUs.
Fixes GPU hangs with Splitgate during automatic settings configuration.
Cc: mesa-stable
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22823>
Following PAL's implementation, this patch avoids allocating shader code
buffers in BAR and use SDMA to upload them to invisible VRAM
directly.
For some games like HZD, shaders can take as much as 400MB, which exceeds
the non-resizable BAR size (256MB) and cause inconsistent spilling
behavior. The kernel will normally move these to invisible VRAM on its own,
but there are a few cases that it does not reliably happen. This patch does
the moving explicitly in the driver to ensure predictable results.
In this patch, we upload the shaders synchronously; so the shader will be
ready as soon as vkCreate*Pipeline returns. A following patch will make
this asynchronous and don't block until we see a use of the pipeline.
As a side effect, when SQTT is used we now store the shaders on a cacheable
buffer which would speed up writing the trace to the disk.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16271>
