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Is this GNU Radio vibe-ported to rust? How does it compare?

by Retr0id 26d ago

Joel_Mckay 26d ago
In general, any llvm compiled language is going to have persistent unpredictable jitter related issues. Only the naive think Rust is a replacement for C/C++, but the same issues also occur with clang compilers for the same reasons. They now have 2 DSP problems by porting to llvm languages like Rust, but will insist their work isn't worse than the C they attempted to "upgrade". =3 https://en.wikipedia.org/wiki/Metastability#Electronic_circuits https://en.wikipedia.org/wiki/Metastability#Electronic_circu... https://www.youtube.com/watch?v=T4Upf_B9RLQ https://www.youtube.com/watch?v=T4Upf_B9RLQ
- newspicel 26d ago
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- ErroneousBosh 26d ago
  > In general, any llvm compiled language is going to have persistent unpredictable jitter related issues. So if I compiled my own SDR software written in C with LLVM/Clang, it would suddenly have jitter issues? Can you explain why?
  - Joel_Mckay 26d ago
    In C, even without inline assembly or "volatile" to gaurentee the same code motion every time, it is still possible to bake what is placed in "register" a priori. In llvm binaries, the code is abstracted/re-ordered, optimized/deduplicated, and flow may operate completely differently with minimal changes. One may gain 11% to 15% raw computational throughput performance, but have no latency guarantees on what the pipeline will do or when. This will often eventually cause intermittent CDC mismatch under load, as the compiler pseudo-randomly decides to do something silly every time something is updated. https://en.wikipedia.org/wiki/Clock_domain_crossing https://en.wikipedia.org/wiki/Clock_domain_crossing The current best solution is to side-load special fpga memory access modules into the multi-tasking kernel space for handling DSP data stream filtering on Zynq. https://en.wikipedia.org/wiki/Finite_impulse_response https://en.wikipedia.org/wiki/Finite_impulse_response https://www.analog.com/en/resources/evaluation-hardware-and-software/evaluation-boards-kits/adalm-pluto.html#eb-overview https://www.analog.com/en/resources/evaluation-hardware-and-... Best of luck, =3
    - acuozzo 26d ago
      Is it possible you're confusing LLVM with JIT compilation? Clang targeting LLVM, despite the name, produces binaries compiled 100% ahead-of-time. The "LLVM" is just the intermediate representation used by the compiler. GCC uses GIMPLE and RTL. > In C... it is still possible to bake what is placed in "register" a priori By what mechanism? Even ancient GCC circa 1989 ignored the "register" keyword/storage-class. Automatic register allocation algorithms have been the default for a long time. You have to go back to the K&R days to find a compiler willing to honor it (or find an esoteric compiler like AZTEC C for the 6502).
      - Joel_Mckay 26d ago
        JIT is even worse, as if you have ever built a compiler one already knows about why backpatching is needed during the generator stages. I cringe every time someone brings up embedded python, and lose hope for future coders. I agree it is subtle, so takes some people a few hours to understand, and for others never. If you work in Application user-space, than it usually won't matter. Note I like Julia, but it is also not a good fit for SDR or low-latency DSP. People seem upset for some reason, but one may want to check out Analog Devices training documentation as a student. =3
        ErroneousBosh 24d ago
        > People seem upset for some reason, but one may want to check out Analog Devices training documentation as a student. =3 You're making some pretty interesting and unusual claims. Can you show a Proof-of-Concept of what you're talking about?
        jeezfrk 25d ago
        Julia is not written in assembly.
        Joel_Mckay 25d ago
        "Julia programs automatically compile to efficient native code via LLVM" ( https://julialang.org/ https://julialang.org/ ) Have a nice day =3
- vrighter 25d ago
  any code in any language in any paradigm will have unpredictable jitter on any superscalar out of order processor. Which is all of them in phones and desktops.
newspicel 26d ago
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Is this GNU Radio vibe-ported to rust? How does it compare?

by Retr0id 26d ago

Is this GNU Radio vibe-ported to rust? How does it compare?

In general, any llvm compiled language is going to have persistent unpredictable jitter related issues. Only the naive think Rust is a replacement for C/C++, but the same issues also occur with clang compilers for the same reasons. They now have 2 DSP problems by porting to llvm languages like Rust, but will insist their work isn't worse than the C they attempted to "upgrade". =3 https://en.wikipedia.org/wiki/Metastability#Electronic_circuits https://en.wikipedia.org/wiki/Metastability#Electronic_circu... https://www.youtube.com/watch?v=T4Upf_B9RLQ https://www.youtube.com/watch?v=T4Upf_B9RLQ

newspicel 26d ago
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ErroneousBosh 26d ago
> In general, any llvm compiled language is going to have persistent unpredictable jitter related issues. So if I compiled my own SDR software written in C with LLVM/Clang, it would suddenly have jitter issues? Can you explain why?
- Joel_Mckay 26d ago
  In C, even without inline assembly or "volatile" to gaurentee the same code motion every time, it is still possible to bake what is placed in "register" a priori. In llvm binaries, the code is abstracted/re-ordered, optimized/deduplicated, and flow may operate completely differently with minimal changes. One may gain 11% to 15% raw computational throughput performance, but have no latency guarantees on what the pipeline will do or when. This will often eventually cause intermittent CDC mismatch under load, as the compiler pseudo-randomly decides to do something silly every time something is updated. https://en.wikipedia.org/wiki/Clock_domain_crossing https://en.wikipedia.org/wiki/Clock_domain_crossing The current best solution is to side-load special fpga memory access modules into the multi-tasking kernel space for handling DSP data stream filtering on Zynq. https://en.wikipedia.org/wiki/Finite_impulse_response https://en.wikipedia.org/wiki/Finite_impulse_response https://www.analog.com/en/resources/evaluation-hardware-and-software/evaluation-boards-kits/adalm-pluto.html#eb-overview https://www.analog.com/en/resources/evaluation-hardware-and-... Best of luck, =3
  - acuozzo 26d ago
    Is it possible you're confusing LLVM with JIT compilation? Clang targeting LLVM, despite the name, produces binaries compiled 100% ahead-of-time. The "LLVM" is just the intermediate representation used by the compiler. GCC uses GIMPLE and RTL. > In C... it is still possible to bake what is placed in "register" a priori By what mechanism? Even ancient GCC circa 1989 ignored the "register" keyword/storage-class. Automatic register allocation algorithms have been the default for a long time. You have to go back to the K&R days to find a compiler willing to honor it (or find an esoteric compiler like AZTEC C for the 6502).
    - Joel_Mckay 26d ago
      JIT is even worse, as if you have ever built a compiler one already knows about why backpatching is needed during the generator stages. I cringe every time someone brings up embedded python, and lose hope for future coders. I agree it is subtle, so takes some people a few hours to understand, and for others never. If you work in Application user-space, than it usually won't matter. Note I like Julia, but it is also not a good fit for SDR or low-latency DSP. People seem upset for some reason, but one may want to check out Analog Devices training documentation as a student. =3
      - ErroneousBosh 24d ago
        > People seem upset for some reason, but one may want to check out Analog Devices training documentation as a student. =3 You're making some pretty interesting and unusual claims. Can you show a Proof-of-Concept of what you're talking about?
      - jeezfrk 25d ago
        Julia is not written in assembly.
        Joel_Mckay 25d ago
        "Julia programs automatically compile to efficient native code via LLVM" ( https://julialang.org/ https://julialang.org/ ) Have a nice day =3
vrighter 25d ago
any code in any language in any paradigm will have unpredictable jitter on any superscalar out of order processor. Which is all of them in phones and desktops.

newspicel 26d ago

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