[Libre-soc-dev] [Mesa-dev] Loading Vulkan Driver

[Jacob Lifshay]

On Sun, Aug 23, 2020, 15:55 Dave Airlie <airlied at gmail.com> wrote:

> What is your work submission model then, Vulkan is designed around
> having work submitted to a secondary processor from a control
> processor. Do you intend for the device to be used only as a
> coprocessor, or as a CPU for normal tasks that can then use the
> features in their threads, because none of the API are designed around
> that model. They have a running thread of execution that queues stuff
> up to a separate execution domain.
>

It's intended to be a combination, where CPU threads schedule work and
render threads dequeue and run the work, probably using something like
Rayon:
https://github.com/rayon-rs/rayon

When a CPU thread waits in the Vulkan driver, it can possibly be used as a
render thread instead of blocking on a futex, avoiding needing excessive
numbers of Linux kernel-level threads.

The CPU and render threads run on the same cores, as scheduled by Linux.

>
> What represents a vulkan queue,


The rayon task queues.

what will be recorded into vulkan
> command buffers,


a command sequence encoded as bytecode, a list of Rust enums, or something
similar.

what will execute those command buffers.


the render threads will dequeue the command buffers, run through all the
commands in them, and schedule the appropriate rendering tasks to rayon's
task execution mechanism.

These are
> the questions you need to ask yourself and answer before writing any
> code.


Yup, did that 2 years ago, though I don't remember if I explicitly wrote
them down before.

Jacob