neka-nat/cupoch

Direct zero-copy from cupy array

Closed this issue · 3 comments

Shipborn commented

I failed to find in the documentation or anywhere in the code comments a way of directly using cupy arrays that I already have loaded on the device?

Right now I am running custom kernels using numba and cupy and it's working like a charm. However when I use cupoch I first need to copy to host and then copy it back to the device using cupoch. This currently takes 30ms on an algorithm that takes a total of 60ms.... so 50% is lost on wasted copying.

Right now I have this workflow
cloud = cupy.asarray(source_data)
*Custom calculations*
cloud_host = cupy.asnumpy(cloud)
gpu = cph.geometry.PointCloud()
gpu.points = cph.utility.Vector3fVector(cloud_host)
*cupoch calculations*

Im sure there is a faster way :)

neka-nat commented

Hi @Shipborn ,

Thank you for the feedback.
You can use dlpack to interact with data in cupy.

cloud = cupy.asarray(source_data)
dltensor = cloud.toDlpack()
gpu = cph.geometry.PointCloud()
gpu.from_points_dlpack(dltensor)
  • 👍1
dHofmeister commented

Thank you @neka-nat,

for reference for others:
To convert the pointcloud back to the host it currently tells you in the variable description "Use numpy.asarray() to copy to host."
Which is identical to the open3D description, implying:
host_array = np.asarray(gpu.points)

but the actual code is:
host_array = np.asarray(gpu.points.cpu())
This is not following the open3D API. not a critique, just a heads-up :)

just for future people to see.

Greetings
Deniz

neka-nat commented

Hi @dHofmeister ,

Thank you for the report!
I've corrected the wording and pushed it to master.
Thanks.

  • 🎉1