Re: Synchronization framework

Re: Synchronization framework

[Maarten Lankhorst]

Hey,

For intel/nouveau hybrid graphics I'm interested in this since it
would allow me to synchronize between intel and nvidia cards
without waiting for rendering to complete.

I'm worried about the api though, nouveau and intel already
have existing infrastructure to deal with fencing so exposing
additional ioctl's will complicate the implementation. Would
it be possible to never expose this interface to userspace
but keep it inside the kernel only?

nouveau_gem_ioctl_pushbuf is what's used for nouveau.
If any dmabuf synch framework could hook into that then
userspace would never have to act differently on shared bo's.

I haven't looked at intel and amd, but from a quick glance
it seems like they already implement fencing too, so just
some way to synch up the fences on shared buffers seems
like it could benefit all graphics drivers and the whole
userspace synching could be done away with entirely.

Cheers,
Maarten

Re: Synchronization framework

[Maarten Lankhorst]

Hey Erik,

Op 07-06-12 19:35, Erik Gilling schreef:
> On Thu, Jun 7, 2012 at 1:55 AM, Maarten Lankhorst
> <m.b.lankhorst@gmail.com> wrote:
>> I haven't looked at intel and amd, but from a quick glance
>> it seems like they already implement fencing too, so just
>> some way to synch up the fences on shared buffers seems
>> like it could benefit all graphics drivers and the whole
>> userspace synching could be done away with entirely.
> It's important to have some level of userspace API so that GPU
> generated graphics can participate in the graphics pipeline.  Think of
> the case where you have a software video codec streaming textures into
> the GPU.  It needs to know when the GPU is done with those textures so
> it can reuse the buffer.
>
In the graphics case this problem already has to be handled without
dma-buf, so adding any extra synchronization api for userspace
that is only used when the bo is shared is a waste.

I do agree you need some way to synch userspace though, but I
think adding a new api for userspace is not the way to go.

Cheers,
Maarten

PS: re-added cc's that seem to have fallen off from your mail.

Re: Synchronization framework

[Erik Gilling]

On Thu, Jun 7, 2012 at 10:52 AM, Maarten Lankhorst
<m.b.lankhorst@gmail.com> wrote:
> I do agree you need some way to synch userspace though, but I
> think adding a new api for userspace is not the way to go.

I'm not sure I understand how you propose to expose the functionality
to userspace in a way that does not depend on the driver that "owns"
the buffer w/o adding an API.

-Erik