[Mesa-dev] [PATCH 09/10] st/vdpau: implement the new DMA-buf based interop

[Ilia Mirkin]

On Wed, Sep 7, 2016 at 12:06 PM, Marek Olšák <maraeo at gmail.com> wrote:
> On Wed, Sep 7, 2016 at 5:36 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> On Wed, Sep 7, 2016 at 4:08 AM, Michel Dänzer <michel at daenzer.net> wrote:
>>> On 07/09/16 04:19 AM, Christian König wrote:
>>>> Am 06.09.2016 um 21:05 schrieb Ilia Mirkin:
>>>>> On Tue, Sep 6, 2016 at 2:22 PM, Christian König
>>>>> <deathsimple at vodafone.de> wrote:
>>>>>> Am 06.09.2016 um 16:23 schrieb Ilia Mirkin:
>>>>>>> On Mon, Sep 5, 2016 at 2:48 AM, Michel Dänzer <michel at daenzer.net>
>>>>>>> wrote:
>>>>>>>> On 05/09/16 04:37 AM, Ilia Mirkin wrote:
>>>>>>>>> On Tue, Mar 8, 2016 at 7:21 AM, Christian König
>>>>>>>>> <deathsimple at vodafone.de> wrote:
>>>>>>>>>> @@ -80,7 +82,7 @@ vlVdpOutputSurfaceCreate(VdpDevice device,
>>>>>>>>>>       res_tmpl.depth0 = 1;
>>>>>>>>>>       res_tmpl.array_size = 1;
>>>>>>>>>>       res_tmpl.bind = PIPE_BIND_SAMPLER_VIEW |
>>>>>>>>>> PIPE_BIND_RENDER_TARGET |
>>>>>>>>>> -                   PIPE_BIND_LINEAR;
>>>>>>>>>> +                   PIPE_BIND_LINEAR | PIPE_BIND_SHARED;
>>>>>>>>> Hi Christian,
>>>>>>>>>
>>>>>>>>> This change appears to have semi-broken vdpau on nouveau. Whenever I
>>>>>>>>> flip on the OSD in mplayer, the rendering becomes *extremely* slow.
>>>>>>>>> However regular up-scaling without the OSD is plenty fast. This
>>>>>>>>> effectively is forcing the output surfaces to live in GART instead of
>>>>>>>>> VRAM.
>>>>>>>> Strictly speaking, they'd only need to be forced to GART while they're
>>>>>>>> actually being shared between different GPUs. That's how it works with
>>>>>>>> the amdgpu and radeon kernel drivers.
>>>>>>> Any suggestions on how to handle this? Perhaps reallocate + copy the
>>>>>>> surface in st/vdpau when actual dmabuf sharing is requested?
>>>>>>>
>>>>>>> To be clear - with this change, vdpau with nouveau is unusable in the
>>>>>>> presence of an OSD in mplayer. The OSD comes up whenever you seek
>>>>>>> around in the video, so in effect, it's unusable. Used to work great.
>>>>>>
>>>>>> Well I think you should clearly figure out why adding
>>>>>> PIPE_BIND_SHARED has
>>>>>> such dramatic effect.
>>>>> Because the buffer goes into GART. And then you try to blend on it,
>>>>> which involves readback from GART (that's how the functions OSD is
>>>>> based on work, I believe). We normally don't allocate renderable
>>>>> surfaces or textures in GART.
>>>>>
>>>>>> We not only need this for DMA-buf based interop, but also for the
>>>>>> DRI3 based
>>>>>> sharing of buffers with X.
>>>>>>
>>>>>> So that clearly sounds like a bug in nouveau to me.
>>>>> OK, so SHARED != GART? With nouveau, buffers are placed statically in
>>>>> either VRAM or GART, so I think that if it's shared it has to end up
>>>>> in GART, no?
>>>>
>>>> As far as I understand it no. Shared just means that we can share it
>>>> between applications, doesn't it? Or does it mean the buffer should be
>>>> shareable between GPUs?
>>>>
>>>> Could be that my understanding was wrong and so if it's the later feel
>>>> free to provide a patch to just remove the flag.
>>>>
>>>>> I'm pretty weak on all these concepts, as well as how the DRI3 stuff
>>>>> works, unfortunately.
>>>>
>>>> I have to confess I'm not so deeply into this stuff either. Marek,
>>>> Michel what exactly is the meaning of the flag?
>>>
>>> According to src/gallium/docs/source/screen.rst:
>>>
>>> * ``PIPE_BIND_SHARED``: A sharable buffer that can be given to another
>>>   process.
>>>
>>> It's also used e.g. for buffers shared via DRI3. So I'm afraid this is
>>> something nouveau has to deal with better.
>>
>> Any suggestions that don't involve rewriting nouveau bo handling at
>> every level (kernel, ddx, mesa)?
>>
>> Otherwise I'll send a revert for this change.
>
> PIPE_BIND_SHARED means texture_get_handle is expected to be used on
> the resource, meaning that inter-API, inter-process, or inter-device
> sharing is possible. All window back buffers should have the flag. If
> they don't, it's a bug. If the flag causes nouveau to put the buffer
> in GART, it's a bug too. There is no reason to use GART for inter-API
> and inter-process sharing like VDPAU and DRI3 are.
>
> To be honest, the flag is pratically useless with respect to EGL and
> VDPAU, which allow sharing almost any texture.
>
> I suggest you fix nouveau. The first step would be to become less
> dependent on BIND flags whose existence is already questionable.

As I suspected, merely flipping away from using PIPE_BIND_SHARED
doesn't work. By flipping the logic like this:

diff --git a/src/gallium/drivers/nouveau/nv50/nv50_miptree.c
b/src/gallium/drivers/nouveau/nv50/nv50_miptree.c
index f2e304f..5532794 100644
--- a/src/gallium/drivers/nouveau/nv50/nv50_miptree.c
+++ b/src/gallium/drivers/nouveau/nv50/nv50_miptree.c
@@ -377,7 +377,8 @@ nv50_miptree_create(struct pipe_screen *pscreen,
    }
    bo_config.nv50.tile_mode = mt->level[0].tile_mode;

-   if (!bo_config.nv50.memtype && (pt->bind & PIPE_BIND_SHARED))
+   if (!bo_config.nv50.memtype && (pt->usage == PIPE_USAGE_STAGING ||
+                                   pt->usage == PIPE_USAGE_STREAM))
       mt->base.domain = NOUVEAU_BO_GART;
    else
       mt->base.domain = NV_VRAM_DOMAIN(nouveau_screen(pscreen));
diff --git a/src/gallium/drivers/nouveau/nvc0/nvc0_miptree.c
b/src/gallium/drivers/nouveau/nvc0/nvc0_miptree.c
index 27674f7..0d009bd 100644
--- a/src/gallium/drivers/nouveau/nvc0/nvc0_miptree.c
+++ b/src/gallium/drivers/nouveau/nvc0/nvc0_miptree.c
@@ -299,7 +299,8 @@ nvc0_miptree_create(struct pipe_screen *pscreen,
    }
    bo_config.nvc0.tile_mode = mt->level[0].tile_mode;

-   if (!bo_config.nvc0.memtype && (pt->usage == PIPE_USAGE_STAGING ||
pt->bind & PIPE_BIND_SHARED))
+   if (!bo_config.nvc0.memtype && (pt->usage == PIPE_USAGE_STAGING ||
+                                   pt->usage == PIPE_USAGE_STREAM))
       mt->base.domain = NOUVEAU_BO_GART;
    else
       mt->base.domain = NV_VRAM_DOMAIN(nouveau_screen(pscreen));

I end up with

nouveau 0000:04:00.0: DRM: Moving pinned object ffff88009503fc00!

when trying to run glxgears with prime. It all works "locally" of
course. So really, what I need is a PIPE_USAGE_MIGHT_BE_PRIME. Nouveau
has been using PIPE_BIND_SHARED for that. Is there a quick fix? Should
I just disable VDPAU on nouveau and stop worrying about it? Make a
copy of the vdpau state tracker and change it so that it works well
with nouveau?

  -ilia