News: 0001652413

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AMD Working On A New Backend For Improving ROCm Compute In QEMU/VMs

([AMD] 56 Minutes Ago Better ROCm For GPU Virtualized Compute)


AMD engineers are working on enhancing the open-source ROCm compute stack for better handling GPU virtualized compute under QEMU.

Last year was a [1]merge request adding ROCm native context support for Virglrenderer. That ROCm native context support has yet to be merged into Virglrenderer for the AMD GPU compute stack for virtualized GPU computing. But now they are looking at a new implementation for providing better support in virtualized environments.

AMD engineer Honglei Huang started a new discussion today around developing a new back-end for ROCm GPU compute under QEMU. With the existing implementation using the VirtIO GPU context type and sharing the display path, they have encountered some roadblocks. Besides many accelerators lacking a display engine, leveraging the VirtIO GPU context type shared with the display path is causing contention and display stuttering. Compute contexts also typically need more memory access than what's allowed, and the ROCm stack not fitting nicely with the render model.

AMD thus is looking at implementing a dedicated headless VirtIO GPU instance solely for compute. They are also developing an open-source ROCm back-end library loaded in-process by QEMU that would be distributed in the future as part of their ROCm stack.

If this topic of AMD ROCm under QEMU for improved virtualized compute is of interest to you, [2]this mailing list thread is where the discussion has begun over this new possible back-end.



[1] https://gitlab.freedesktop.org/virgl/virglrenderer/-/merge_requests/1568

[2] https://lore.kernel.org/dri-devel/4673d669-b350-4723-b74e-6e1ea5f09c22@amd.com/T/



I myself have dreamed up a structure intermediate between Dyson spheres
and planets. Build a ring 93 million miles in radius -- one Earth orbit
-- around the sun. If we have the mass of Jupiter to work with, and if
we make it a thousand miles wide, we get a thickness of about a thousand
feet for the base.

And it has advantages. The Ringworld will be much sturdier than a Dyson
sphere. We can spin it on its axis for gravity. A rotation speed of 770
m/s will give us a gravity of one Earth normal. We wouldn't even need to
roof it over. Place walls one thousand miles high at each edge, facing the
sun. Very little air will leak over the edges.

Lord knows the thing is roomy enough. With three million times the surface
area of the Earth, it will be some time before anyone complains of the
crowding.
-- Larry Niven, "Ringworld"