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I want a good parallel computer

raphlinus.github.io

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Re: I want a good parallel computer

#51

Post by amelius »

Animats wrote: post #32

Interesting article. Other than as an exercise, it's not clear why someone would write a massively parallel 2D renderer that needs a GPU. Modern GPUs are overkill for 2D. Now, 3D renderers, we need all the help we can get. In this context, a "renderer" is something that takes in meshes, textures, materials, transforms, and objects, and generates images. It's not an entire game development engine, such as Unreal, Unit…

> Other than as an exercise, it's not clear why someone would write a massively parallel 2D renderer that needs a GPU. Modern GPUs are overkill for 2D.

Depends on how complicated your artwork is.

Re: I want a good parallel computer

#54

Post by api »

I implemented some evolutionary computation stuff on the Cell BE in college. It was a really interesting machine and could be very fast for its time but it was somewhat painful to program.

The main cores were PPC and the Cell cores were… a weird proprietary architecture. You had to write kernels for them like GPGPU, so in that sense it was similar. You couldn’t use them seamlessly or have mixed work loads easily.

Larrabee and Xeon Phi are closer to what I’d want.

I’ve always wondered about many—many-many-core CPUs too. How many tiny ARM32 cores could you put on a big modern 5nm die? Give each one local RAM and connect them with an on die network fabric. That’d be an interesting machine for certain kinds of work loads. It’d be like a 1990s or 2000s era supercomputer on a chip but with much faster clock, RAM, and network.

Re: I want a good parallel computer

#55

Post by deviantbit »

morphle wrote: post #39
deviantbit wrote: post #36

Earlier quoted context omitted.

Let’s be honest, saying “just fix the page tables” is like telling someone they can fly if they “just rewrite gravity.” Yes, on Apple Silicon, the hardware supports shared physical memory, and with enough “convincing”, you can rig up a contiguous virtual address space for both the CPU and GPU. Apple’s unified memory architecture makes that possible, but Apple’s APIs and memory managers don’t expose this easily or saf…

Oh yes I programmed all the Amiga models, mostly in assembly level. I reprogrammed the ROMs. I also published a magazine on all the Commodore computers internals and build lots of hardware for these machines. We had the parallel Inmos Transputer systems during the heyday of the Amiga, they where much better designed than any the custom Amiga chips.

Inmos was a disaster. No application ever shipped on one. EVER. It used a serial bus to resolve the problems that should have never been problems. Clearly you never wrote code for one. Each oslink couldn't reach more than 3 feet. What a disaster that entire architecture was.

Re: I want a good parallel computer

#56

Post by api »

deviantbit wrote: post #49

"I believe there are two main things holding it back." He really science’d the heck out of that one. I’m getting tired of seeing opinions dressed up as insight—especially when they’re this detached from how real systems actually work. I worked on the Cell processor and I can tell you it was a nightmare. It demanded an unrealistic amount of micromanagement and gave developers rope to hang themselves with. There’s a re…

On flattening address spaces: the road not taken here is to run everything in something akin to the JVM, CLR, or WASM. Do that stuff in software not hardware.

You could also do things like having the JIT optimize the entire running system dynamically like one program, eliminating syscall and context switch overhead not to mention most MMU overhead.

Would it be faster? Maybe. The JIT would have to generate its own safety and bounds checking stuff. I’m sure some work loads would benefit a lot and others not so much.

What it would do is allow CPUs to be simpler, potentially resulting in cheaper lower power chips or more cores on a die with the same transistor budget. It would also make portability trivial. Port the core kernel and JIT and software doesn’t care.

Re: I want a good parallel computer

#57

Post by deviantbit »

morphle wrote: post #43
deviantbit wrote: post #36

Earlier quoted context omitted.

Let’s be honest, saying “just fix the page tables” is like telling someone they can fly if they “just rewrite gravity.” Yes, on Apple Silicon, the hardware supports shared physical memory, and with enough “convincing”, you can rig up a contiguous virtual address space for both the CPU and GPU. Apple’s unified memory architecture makes that possible, but Apple’s APIs and memory managers don’t expose this easily or saf…

Not true. "just fix the page tables" took me 4 hours. And only 15 minutes with the Linux kernel on Apple Silicon.

Obviously you missed the sarcasm.

Re: I want a good parallel computer

#58

Post by sitkack »

deviantbit wrote: post #49

"I believe there are two main things holding it back." He really science’d the heck out of that one. I’m getting tired of seeing opinions dressed up as insight—especially when they’re this detached from how real systems actually work. I worked on the Cell processor and I can tell you it was a nightmare. It demanded an unrealistic amount of micromanagement and gave developers rope to hang themselves with. There’s a re…

Those students would all drop out and start meditating. That would be a fun course. Speed run developing for all the prickly architectures of the 80s and 90s.

Re: I want a good parallel computer

#59

Post by deviantbit »

sitkack wrote: post #58
deviantbit wrote: post #49

"I believe there are two main things holding it back." He really science’d the heck out of that one. I’m getting tired of seeing opinions dressed up as insight—especially when they’re this detached from how real systems actually work. I worked on the Cell processor and I can tell you it was a nightmare. It demanded an unrealistic amount of micromanagement and gave developers rope to hang themselves with. There’s a re…

Those students would all drop out and start meditating. That would be a fun course. Speed run developing for all the prickly architectures of the 80s and 90s.

I see what you did there.

Re: I want a good parallel computer

#60

Post by sitkack »

deviantbit wrote: post #55
morphle wrote: post #39

Earlier quoted context omitted.

Oh yes I programmed all the Amiga models, mostly in assembly level. I reprogrammed the ROMs. I also published a magazine on all the Commodore computers internals and build lots of hardware for these machines. We had the parallel Inmos Transputer systems during the heyday of the Amiga, they where much better designed than any the custom Amiga chips.

Inmos was a disaster. No application ever shipped on one. EVER. It used a serial bus to resolve the problems that should have never been problems. Clearly you never wrote code for one. Each oslink couldn't reach more than 3 feet. What a disaster that entire architecture was.

Hey don't shit on my retro alternative timeline nostalgia. We were all writing Lisp programs on 64 CPU Transputer systems with FPGA coprocessors, dynamically reconfigured in realtime with APL.
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