On Sat, Apr 9, 2022 at 7:33 AM Christian König christian.koenig@amd.com wrote:

Am 08.04.22 um 23:12 schrieb Chia-I Wu:

...

In practice, trace_dma_fence_init is good enough and almost no driver calls trace_dma_fence_emit. But this is still more correct in theory.

Well, the reason why basically no driver is calling this is because it is pretty much deprecated.

Why is it considered deprecated? trace_dma_fence_{emit,signaled} are useful to visualize fence timelines. I am actually less sure about how trace_dma_fence_{init,destroy} are used.

Is it because trace_dma_fence_init is called automatically, and is good enough most of the time?

We do have a case in the GPU scheduler where it makes sense to distinct between init and emit, but it doesn't really matter for drivers.

virtio also has a case where init and emit can be far apart, when the host cannot process commands fast enough and there is no space in virtqueue.

So I'm not sure if it's a good idea to add that here.

Regards, Christian.

...

Signed-off-by: Chia-I Wu olvaffe@gmail.com Cc: Rob Clark robdclark@chromium.org

---

drivers/gpu/drm/msm/msm_gpu.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c index faf0c242874e..a82193f41ea2 100644 --- a/drivers/gpu/drm/msm/msm_gpu.c +++ b/drivers/gpu/drm/msm/msm_gpu.c @@ -15,6 +15,7 @@ #include <linux/string_helpers.h> #include <linux/devcoredump.h> #include <linux/sched/task.h> +#include <trace/events/dma_fence.h>

/*

• Power Management:

@@ -769,6 +770,7 @@ void msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit) gpu->active_submits++; mutex_unlock(&gpu->active_lock);

• trace_dma_fence_emit(submit->hw_fence);
  gpu->funcs->submit(gpu, submit);
  gpu->cur_ctx_seqno = submit->queue->ctx->seqno;
  
  

Sorry for the delayed reply.

Am 12.04.22 um 21:41 schrieb Rob Clark:

On Sat, Apr 9, 2022 at 7:33 AM Christian König christian.koenig@amd.com wrote:

...

Am 08.04.22 um 23:12 schrieb Chia-I Wu:

...

In practice, trace_dma_fence_init is good enough and almost no driver calls trace_dma_fence_emit. But this is still more correct in theory.

Well, the reason why basically no driver is calling this is because it is pretty much deprecated.

We do have a case in the GPU scheduler where it makes sense to distinct between init and emit, but it doesn't really matter for drivers.

So I'm not sure if it's a good idea to add that here.

visualization can't easily differentiate between drivers/timelines where the split matters and ones where it doesn't.. IMO it is better to just have the extra trace even in the cases where it comes at the same time as the init trace

That's exactly the reason why I want to remove the extra trace.

To make it clear this is only useful for debugging and *NOT* for actually visualizing things.

So by adding that here you add more confusion than solving anything.

Regards, Christian.

BR, -R

...

Regards, Christian.

...

Signed-off-by: Chia-I Wu olvaffe@gmail.com Cc: Rob Clark robdclark@chromium.org

---

drivers/gpu/drm/msm/msm_gpu.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c index faf0c242874e..a82193f41ea2 100644 --- a/drivers/gpu/drm/msm/msm_gpu.c +++ b/drivers/gpu/drm/msm/msm_gpu.c @@ -15,6 +15,7 @@ #include <linux/string_helpers.h> #include <linux/devcoredump.h> #include <linux/sched/task.h> +#include <trace/events/dma_fence.h>

/* * Power Management: @@ -769,6 +770,7 @@ void msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit) gpu->active_submits++; mutex_unlock(&gpu->active_lock);

• trace_dma_fence_emit(submit->hw_fence);
   gpu->funcs->submit(gpu, submit);
   gpu->cur_ctx_seqno = submit->queue->ctx->seqno;