On Thu, Jun 24, 2021 at 07:03:10PM +0200, Christian König wrote:
Am 24.06.21 um 16:00 schrieb Daniel Vetter:
This is essentially part of drm_sched_dependency_optimized(), which only amdgpu seems to make use of. Use it a bit more.
Signed-off-by: Daniel Vetter daniel.vetter@intel.com Cc: "Christian König" christian.koenig@amd.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Luben Tuikov luben.tuikov@amd.com Cc: Andrey Grodzovsky andrey.grodzovsky@amd.com Cc: Alex Deucher alexander.deucher@amd.com Cc: Jack Zhang Jack.Zhang1@amd.com
drivers/gpu/drm/scheduler/sched_main.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c index 370c336d383f..c31d7cf7df74 100644 --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -649,6 +649,13 @@ int drm_sched_job_await_fence(struct drm_sched_job *job, if (!fence) return 0;
- /* if it's a fence from us it's guaranteed to be earlier */
- if (fence->context == job->entity->fence_context ||
fence->context == job->entity->fence_context + 1) {dma_fence_put(fence);return 0;- }
Well NAK. That would break Vulkan.
The problem is that Vulkan can insert dependencies between jobs which run on the same queue.
So we need to track those as well and if the previous job for the same queue/scheduler is not yet finished a pipeline synchronization needs to be inserted.
That's one of the reasons we wasn't able to unify the dependency handling yet.
That sounds like an extremely amdgpu specific constraint? You're also the only one who keeps track of whether the previous job we've scheduled has finished already (I guess they can get pipelined and you don't flush by default), so you insert fences.
I guess we can add a await_fence_no_dedup or so for amdgpu, but I'm not sure why we have to inflict this design constraint on all other drivers? At least I'm not seeing anything in lima, panfrost, v3d or entaviv that would break with this, and i915 will also be perfectly fine.
Also note: I'm not using this for amdgpu, exactly because there's a few funny things going on.
Finally: You _really_ need explicit dependency handling for vulkan in your uapi, instead of the kernel second-guessing what userspace might be doing. That's really not how vulkan is designed to work :-)
Cheers, Daniel
Christian.
/* Deduplicate if we already depend on a fence from the same context. * This lets the size of the array of deps scale with the number of * engines involved, rather than the number of BOs.