[PATCH v2] drm/msm: add trace_dma_fence_emit to msm_gpu_submit

[Rob Clark]

On Tue, Apr 26, 2022 at 10:08 AM Christian König
<christian.koenig at amd.com> wrote:
>
> Am 26.04.22 um 19:05 schrieb Rob Clark:
> > On Tue, Apr 26, 2022 at 9:42 AM Christian König
> > <christian.koenig at amd.com> wrote:
> >> Am 26.04.22 um 18:32 schrieb Chia-I Wu:
> >>> On Tue, Apr 12, 2022 at 2:26 PM Chia-I Wu <olvaffe at gmail.com> wrote:
> >>>> In practice, trace_dma_fence_init called from dma_fence_init is good
> >>>> enough and almost no driver calls trace_dma_fence_emit.  But drm_sched
> >>>> and virtio both have cases where trace_dma_fence_init and
> >>>> trace_dma_fence_emit can be apart.  It is easier for visualization tools
> >>>> to always use the more correct trace_dma_fence_emit when visualizing
> >>>> fence timelines.
> >>>>
> >>>> v2: improve commit message (Dmitry)
> >>>>
> >>>> Signed-off-by: Chia-I Wu <olvaffe at gmail.com>
> >>>> Cc: Rob Clark <robdclark at chromium.org>
> >>>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> >>> This has been reviewed.  Should we land it?
> >> No, there are still open discussions about it.
> > I think if it is needed for trace visualization, that is justification
> > enough for me
> >
> > I don't really see otherwise how a generic trace visualization tool
> > like perfetto would handle the case that some fence timelines have
> > separate events but others do not.
>
> Well I just send a patch to completely remove the trace point.
>
> As I said it absolutely doesn't make sense to use this for
> visualization, that's what the trace_dma_fence_init trace point is good for.
>
> The only use case is for debugging the GPU scheduler and we should
> probably introduce a separate GPU scheduler specific trace point for
> this instead if we should ever need it.

Hmm, AFAIU from Chia-I, virtgpu has a separation of init and emit..
OTOH if using separate events in these special cases is better, then
I'm ok with that and can revert this patch.  Chia-I is more familiar
with the visualization end of it, so I'll let him comment on whether
that is a workable approach.

BR,
-R

> Regards,
> Christian.
>
> >
> > BR,
> > -R
> >
> >> Regards,
> >> Christian.
> >>
> >>> (Or, how do I check if it has landed?)
>