wl_surface_commit from different thread

[Prabhu S]

Please find my comments inline.




On Fri, Feb 7, 2014 at 8:18 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:

> Hi Prabhu,
> Could you be a little more specific as to what you are doing.  It sounds
> like you are either writing a client or trying to write the client-side
> wayland bits for a driver stack.  However, it's kind of hard from you
> description to tell exactly what you're working on.  Nevertheless, I will
> try to answer your question as best I can.
>
=> Adding support to EGL for wayland

>
> While Weston itself is single-threaded, the libwayland client library can
> handle multiple threads rather well.  Look into wl_event_queue which allows
> you to manage what events get called on what thread.  Also, any request can
> be called from any thread.  The only issue is in the synchronization that
> your app may need to do (know when wl_surface.commit occurs relative to
> wl_shell_surface.set_maximized for instance).  If you want to get a frame
> completion event in another thread, simply call wl_surface.frame,
> wl_surface.commit and then add the callback you got from wl_surface.frame
> to the wl_event_queue for that thread.
>

> Also, I'm confused by the relationship between your eglSwapBuffers calls
> and your wl_surface.commit calls.  eglSwapBuffers should be calling
> wl_surface.commit before it returns.  Sometimes this means the underlying
> graphics drivers pass sync fences or do other things to keep from doing a
> full glFinish and stalling the GPU. Therefore, in most cases, you shouldn't
> need to be calling wl_surface.commit manually.  Perhaps I'm just
> misunderstanding something?
>

=> I'm taking reference of dri2_swap_buffers_with_damage from
http://cgit.freedesktop.org/mesa/mesa/tree/src/egl/drivers/dri2/platform_wayland.c.
Assume 3D frame is complex and really takes more time for the 3D GPU to
complete the frame, GPU will be still processing the frame after return
from eglSwapBuffers. I will get notification of the frame completion in
different thread. In my assumption calls following wl_surface.attach,
wl_surface.damage, wl_surface.commit, wl_display.flush need to be called
from in different thread. Can this possible by creating callback and
setevent from different thread(frame completion thread). I assumg
wl_surface.frame is the compositor frame completion event??


>
> I hope that helps,
> --Jason Ekstrand
>
>
> On Fri, Feb 7, 2014 at 8:03 AM, Prabhu S <prabhusundar at gmail.com> wrote:
>
>> Hello,
>> eglSwapBuffers is a non blocking call. Normally, 3D GPU will be used both
>> for content creation and composition, in that case everything will end up
>> the GPU unit. So the end frame will be will be synchronized. (assuming 1
>> GPU unit).
>>
>> I have a scenario, where 3D GPU being used for creating content and blit
>> engine used for Weston composition. I'm getting frame completion from 3D
>> engine in different thread (not in the same thread eglSwapBuffers calling
>> thread). Currently eglSwapBuffers calling thread need to wait for the frame
>> completion and then call wl_surface_commit to notify Wayland compositor.
>> This takes out most of the performance since GPUs are not active all the
>> time.
>>
>> wl_surface_commit cannot be called from different thread AFAIK. Some
>> advise, suggestions would be appreciated.
>>
>> Thanks
>> Prabhu
>>
>> _______________________________________________
>> wayland-devel mailing list
>> wayland-devel at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/wayland-devel
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/wayland-devel/attachments/20140207/936d1524/attachment.html>