uhm, did you know that waypipe with ssh is fast enough to use blender remotely over wi-fi?
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@tauon @mntmn @uecker Let me put it this way, when I render frame 1 of a GPU program, in order to execute the GPU commands to produce that frame, I need to have the *entire up to date contents of vram* in the 'client' gpu's vram (or at least memory accessible to the 'client' gpu). That's really hard, and is bounded only by the GPU memory that the application wants to use. But using the 'server' gpu to render a frame, and sending it to the remote, is a bounded, and much smaller amount of work.
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@tauon @mntmn @uecker Let me put it this way, when I render frame 1 of a GPU program, in order to execute the GPU commands to produce that frame, I need to have the *entire up to date contents of vram* in the 'client' gpu's vram (or at least memory accessible to the 'client' gpu). That's really hard, and is bounded only by the GPU memory that the application wants to use. But using the 'server' gpu to render a frame, and sending it to the remote, is a bounded, and much smaller amount of work.
@tauon @mntmn @uecker If I have a tool like blender which might have GPU memory requirements of say, 10GB, for a particular scene. Then in order to remote that very first frame, I need to send those entire 10GB all to the client! And then every frame the data in the GPU working set changes, and all that data needs to be sent as well.
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@tauon @mntmn @uecker Let me put it this way, when I render frame 1 of a GPU program, in order to execute the GPU commands to produce that frame, I need to have the *entire up to date contents of vram* in the 'client' gpu's vram (or at least memory accessible to the 'client' gpu). That's really hard, and is bounded only by the GPU memory that the application wants to use. But using the 'server' gpu to render a frame, and sending it to the remote, is a bounded, and much smaller amount of work.
@dotstdy@mastodon.social @mntmn@mastodon.social @uecker@mastodon.social in 9p there is literally no distinction between the "client gpu" or "server gpu". it's literally just a gpu file somewhere
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@uecker @tauon @mntmn I'm not sure I even understand what you're saying in that case, waypipe does just stream the rendered buffer from the host to a remote client. It just doesn't serialize and send the GPU commands required to render that buffer on the remote client. The latter is very hard, the former is very practical.
@dotstdy @tauon @mntmn I think we may be talking past each other. I am not arguing for remote rendering (although I do something like this, but this is more compute than rendering), but my point is that GPU programming *is* programming a remote device because the PCI bus - although less than a network - is a bottleneck and this is why both X and Wayland a remote buffer management protocols and not fundamentally different in this respect.
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@dotstdy @tauon @mntmn I think we may be talking past each other. I am not arguing for remote rendering (although I do something like this, but this is more compute than rendering), but my point is that GPU programming *is* programming a remote device because the PCI bus - although less than a network - is a bottleneck and this is why both X and Wayland a remote buffer management protocols and not fundamentally different in this respect.
@uecker @tauon @mntmn Right, I think I see your meaning now. I was just confused because X (as well as some other products) did of course allow you to send actual rendering commands to the remote machine, for them to be executed on the remote rather than the host. And tauon was talking specifically about forwarding gl commands. But if you just consider the direct rendering paths, then they're pretty similar between something like X and waypipe, it's just copying and forwarding the output frames.
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@dotstdy @tauon @mntmn I think we may be talking past each other. I am not arguing for remote rendering (although I do something like this, but this is more compute than rendering), but my point is that GPU programming *is* programming a remote device because the PCI bus - although less than a network - is a bottleneck and this is why both X and Wayland a remote buffer management protocols and not fundamentally different in this respect.
@uecker @tauon @mntmn nitpick aside: The reason that these are remote buffer management protocols is actually subtly different from bandwidth concerns, it's more about queuing and throughput. the latency between the GPU and the CPU is actually pretty low, and the bandwidth quite high, however we deliberately introduce extra latency in order to allow the GPU to run out-of-lockstep from the CPU to increase throughput. It prevents us from starving the GPU, by ensuring a continuous stream of work.
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@uecker @tauon @mntmn nitpick aside: The reason that these are remote buffer management protocols is actually subtly different from bandwidth concerns, it's more about queuing and throughput. the latency between the GPU and the CPU is actually pretty low, and the bandwidth quite high, however we deliberately introduce extra latency in order to allow the GPU to run out-of-lockstep from the CPU to increase throughput. It prevents us from starving the GPU, by ensuring a continuous stream of work.
@uecker @tauon @mntmn So when you communicate, the reason that's bad is partially due to the bandwidth, but mostly due to the huge delays you incur in order to wait for execution to complete on the GPU, and then to start back up again once you produce more GPU commands. Readback at a fixed latency which exceeds that queuing delay is totally fine, and bandwidth-wise you can yeet something like 20 4k uncompressed images across the pcie link per 60Hz frame, if you really really wanted to.
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