[PATCH] drm/amdgpu: unpack dma_fence_chain containers during sync

[Pierre-Loup A. Griffais]

I just built my kernel with it and tested Horizon Zero Dawn on stock 
Proton 5.13, and it doesn't seem to change things there.

This pattern looks identical as with before the kernel patch, as far as 
I can tell:

https://imgur.com/a/1fZWgNG

The last purple block is a piece of GPU work on the gfx ring. It's been 
queued by software 0.7ms ago, but doesn't get put on the HW ring until 
right after the previous piece of GPU work completes. The orange chunk 
below is the 'gfx' kernel task executing, to queue it.

Thanks,

  - Pierre-Loup

On 2020-11-23 18:09, Marek Olšák wrote:
> Pierre-Loup, does this do what you requested?
>
> Thanks,
> Marek
>
> On Mon, Nov 23, 2020 at 3:17 PM Christian König 
> <ckoenig.leichtzumerken at gmail.com 
> <mailto:ckoenig.leichtzumerken at gmail.com>> wrote:
>
>     That the CPU round trip is gone now.
>
>     Christian.
>
>     Am 23.11.20 um 20:49 schrieb Marek Olšák:
>>     What is the behavior we should expect?
>>
>>     Marek
>>
>>     On Mon, Nov 23, 2020 at 7:31 AM Christian König
>>     <ckoenig.leichtzumerken at gmail.com
>>     <mailto:ckoenig.leichtzumerken at gmail.com>> wrote:
>>
>>         Ping, Pierre/Marek does this change works as expected?
>>
>>         Regards,
>>         Christian.
>>
>>         Am 18.11.20 um 14:20 schrieb Christian König:
>>         > This allows for optimizing the CPU round trip away.
>>         >
>>         > Signed-off-by: Christian König <christian.koenig at amd.com
>>         <mailto:christian.koenig at amd.com>>
>>         > ---
>>         >   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c   |  2 +-
>>         >   drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c | 27
>>         ++++++++++++++++++++++++
>>         >   drivers/gpu/drm/amd/amdgpu/amdgpu_sync.h |  1 +
>>         >   3 files changed, 29 insertions(+), 1 deletion(-)
>>         >
>>         > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>         b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>         > index 79342976fa76..68f9a4adf5d2 100644
>>         > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>         > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>         > @@ -1014,7 +1014,7 @@ static int
>>         amdgpu_syncobj_lookup_and_add_to_sync(struct amdgpu_cs_parser *p,
>>         >               return r;
>>         >       }
>>         >
>>         > -     r = amdgpu_sync_fence(&p->job->sync, fence);
>>         > +     r = amdgpu_sync_fence_chain(&p->job->sync, fence);
>>         >       dma_fence_put(fence);
>>         >
>>         >       return r;
>>         > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
>>         b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
>>         > index 8ea6c49529e7..d0d64af06f54 100644
>>         > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
>>         > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
>>         > @@ -28,6 +28,8 @@
>>         >    *    Christian König <christian.koenig at amd.com
>>         <mailto:christian.koenig at amd.com>>
>>         >    */
>>         >
>>         > +#include <linux/dma-fence-chain.h>
>>         > +
>>         >   #include "amdgpu.h"
>>         >   #include "amdgpu_trace.h"
>>         >   #include "amdgpu_amdkfd.h"
>>         > @@ -169,6 +171,31 @@ int amdgpu_sync_fence(struct
>>         amdgpu_sync *sync, struct dma_fence *f)
>>         >       return 0;
>>         >   }
>>         >
>>         > +/**
>>         > + * amdgpu_sync_fence_chain - unpack dma_fence_chain and sync
>>         > + *
>>         > + * @sync: sync object to add fence to
>>         > + * @f: potential dma_fence_chain to sync to.
>>         > + *
>>         > + * Add the fences inside the chain to the sync object.
>>         > + */
>>         > +int amdgpu_sync_fence_chain(struct amdgpu_sync *sync,
>>         struct dma_fence *f)
>>         > +{
>>         > +     int r;
>>         > +
>>         > +     dma_fence_chain_for_each(f, f) {
>>         > +             if (dma_fence_is_signaled(f))
>>         > +                     continue;
>>         > +
>>         > +             r = amdgpu_sync_fence(sync, f);
>>         > +             if (r) {
>>         > +                     dma_fence_put(f);
>>         > +                     return r;
>>         > +             }
>>         > +     }
>>         > +     return 0;
>>         > +}
>>         > +
>>         >   /**
>>         >    * amdgpu_sync_vm_fence - remember to sync to this VM fence
>>         >    *
>>         > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.h
>>         b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.h
>>         > index 7c0fe20c470d..b142175b65b6 100644
>>         > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.h
>>         > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.h
>>         > @@ -48,6 +48,7 @@ struct amdgpu_sync {
>>         >
>>         >   void amdgpu_sync_create(struct amdgpu_sync *sync);
>>         >   int amdgpu_sync_fence(struct amdgpu_sync *sync, struct
>>         dma_fence *f);
>>         > +int amdgpu_sync_fence_chain(struct amdgpu_sync *sync,
>>         struct dma_fence *f);
>>         >   int amdgpu_sync_vm_fence(struct amdgpu_sync *sync, struct
>>         dma_fence *fence);
>>         >   int amdgpu_sync_resv(struct amdgpu_device *adev, struct
>>         amdgpu_sync *sync,
>>         >                    struct dma_resv *resv, enum
>>         amdgpu_sync_mode mode,
>>
>>         _______________________________________________
>>         amd-gfx mailing list
>>         amd-gfx at lists.freedesktop.org
>>         <mailto:amd-gfx at lists.freedesktop.org>
>>         https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>>
>
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