Re: [Qemu-devel] RFC: running the user interface in a thread ...

[Dave Airlie]

On 18 January 2016 at 19:54, Gerd Hoffmann <address@hidden> wrote:
>   Hi folks,
>
> I'm starting to investigate if and how we can move the user interface
> code into its own thread instead of running it in the iothread and
> therefore avoid blocking the guest in case some UI actions take a little
> longer.
>
> opengl and toolkits tend to be bad at multithreading.  So my idea is to
> have a single thread dedicated to all the UI + rendering stuff, possibly
> let even the virglrenderer run in ui thread context.

I'd still like virgl to run it its own thread at some point like
dataplane but for virgl I suppose.

We see cases where backend GLSL compiles and end up taking quite a
while, and I'd prefer
to not block the UI or qemu on those.

I've hacked on this before, but only with SDL and it was pretty dirty,
and it gave a fairly decent
speed up.

My thoughts are to use dataplane like design to process the queue in a
separate thread,
and then have some sort of channel between the UI and virtio-gpu
thread to handle things like
screen resize etc.

http://cgit.freedesktop.org/~airlied/qemu/commit/?h=dave3d&id=fe22a0955255afef12b947c4a91efa57e7a7c429
is my previous horror patch.

Dave.