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yulaow • today at 12:01 PM • 1 reply • view on HN

I am not in META but for what I read on blind, assuming it is true, they are not spending any time in long planning sessions or in getting into details of the implementation plan at all, and they could not anymore considering how many PRs in parallel they are requested to manage

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spacedcowboy • today at 12:44 PM

Yeah, I'm retired. The only person I have to answer to regarding progress is me. I'm a stubborn son of a bitch when it comes to choosing quality over speed...

That doesn't mean I don't like progress mind :) This morning I got the preliminary results of a 'C' front-end to the compiler (it uses clang to compile to LLVM IR, then translates to our IR, then feeds that IR into the autovectoriser as if it had parsed the code itself). So for the exact same source code I now have:

     ┌─────────────┬────────────┬──────────────────────┬──────────┐
     │  Benchmark  │ clang -O2  │ xcc --par-auto (GPU) │ Speed-up │
     ├─────────────┼────────────┼──────────────────────┼──────────┤
     │ saxpy       │ 1,546 µs   │ 726 µs               │ 2.1×     │
     ├─────────────┼────────────┼──────────────────────┼──────────┤
     │ Mandelbrot  │ 394,238 µs │ 2,110 µs             │ 187×     │
     ├─────────────┼────────────┼──────────────────────┼──────────┤
     │ nbody       │ 37,090 µs  │ 1,035 µs             │ 36×      │
     ├─────────────┼────────────┼──────────────────────┼──────────┤
     │ perlin      │ 78,016 µs  │ 1,850 µs             │ 42×      │
     ├─────────────┼────────────┼──────────────────────┼──────────┤
     │ mandel_deep │ 73.2 s     │ 55.8 ms              │ 1,312×   │
     └─────────────┴────────────┴──────────────────────┴──────────┘
Those are some pretty fine speedups, from naive C, with no alterations from the standard "C" code - it automatically finds places that can be made data-parallel, tracks the data-hazards to make sure its safe to "GPU" and writes all the kernels, boilerplate and data-stream-management if necessary. Obviously the checksums have to match, so I know it did the work correctly too :)

Hacker News isn't interested - any post I make linking to the webpages is immediately blocked/dead so I'll wait until the C++ front-end is ready (some time next week) and announce it somewhere else. A compiler that takes standard C/C++ code and speeds it up by automatically finding data-parallel areas and scheduling them on the GPU with no programming overhead is pretty rare.

Oh, and it manages the local network as well, so you can run xcd on machines on your lan, or via the TB4/5 bridge between Macs and it'll schedule on other GPUs, just like it manages multiple GPUs on the local machine. It characterises both latency and compute-time to figure out which devices are worth scheduling on.

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