Re: [Qemu-devel] [PATCH] virtio_gpu_3d: make it possible to configure the fence poll time

[Marc-André Lureau]

Hi

On Thu, May 23, 2019 at 4:54 PM Gert Wollny <address@hidden> wrote:
>
> Am Donnerstag, den 23.05.2019, 16:37 +0200 schrieb Marc-André Lureau:
> > Hi
> >
> > On Thu, May 23, 2019 at 4:17 PM Gert Wollny <
> > address@hidden> wrote:
> > > Am Donnerstag, den 23.05.2019, 16:01 +0200 schrieb Marc-André
> > > Lureau:
> > > > Hi
> > > >
> > > > On Thu, May 23, 2019 at 3:27 PM Gert Wollny <
> > > > address@hidden> wrote:
> > > > > The default fence poll time of 10ms (100 Hz) is sufficent for
> > > > > normal
> > > > > work loads, but if one wants to play games within the virtual
> > > > > machine
> > > > > this value might be too high, so make it possible to configure
> > > > > this
> > > > > value by using the environment variable QEMU_VIRGL_POLL_FREQ
> > > > > where
> > > > > the
> > > > > poll is given in Hz. To acommodate higher poll frequencies also
> > > > > change
> > > > > the timer to use micro seconds as base instead of milliseconds.
> > > > >
> > > > >
> > > >
> > > > This is what VIRGL_RENDERER_THREAD_SYNC helps with. You don't
> > > > need to
> > > > do regular polling, but I think it is currently limited to
> > > > Linux/eventfd only.
> > >
> > > As far as I can see only vtest uses this, not qemu.
> >
> > I don't think there is anything preventing qemu from using it, except
> > the portability which should be taken care more carefully.
>
> But to actually use it would need quite some work, wouldn't it? (I'm
> thinking of your series:
> http://qemu.11.n7.nabble.com/PATCH-00-18-virgl-use-a-seperate-rendering-thread-tt429557.html
> )
>

I think you could use VIRGL_RENDERER_THREAD_SYNC, without using a
seperate thread for virgl.

You need to register the pollfd virgl_renderer_get_poll_fd() with the
main loop, but other than that it should, in theory, work.



-- 
Marc-André Lureau