• Yote.zip@pawb.social
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    1 year ago

    “This is on version 4 and approved by many people and it doesn’t even work. How was this tested?” types furiously in comic sans

    This video is killing me. Very entertaining to share their frustration.

    Edit: “When we reach 25k subscribers I will debug the Linux scheduler”

    • poVoq@slrpnk.net
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      1 year ago

      AMD’s software has always been in a very sorry state. Only after non-inhouse developers created an alternative GPU driver from scratch for Linux it became feasible to use.

  • trclst@lemmy.mlOP
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    1 year ago

    I am not the creator of the video but amazed what it all makes it into the stable branch.

    • NoXPhasma@lemmy.world
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      1 year ago

      AMD patches for preferred core (prefer those cores which can clock higher) are a mess and ended up not working because of a wrong if condition. Showing that no one at AMD even tested it before submitting. The programmer in the video complains about AMDs developers being incompetent and shows how it’s fixed.

    • Olissipo@programming.dev
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      1 year ago

      Apparently there’s a bug in an AMD’s driver. It was supposed to assign processes based on each core’s self reported performance, but because of the bug it was random.

      This “self reported performance” is based on evaluation done to the cores in the fab process, by AMD. Meaning, due to imperfections some cores are a bit better than others.

      • NoXPhasma@lemmy.world
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        1 year ago

        It’s not just random, it simply does not even work. Because they set this:

        +/*Preferred Core featue is supported*/
        +static bool prefcore = true;
        

        And later in the code they do the if condition wrong:

        +	if (prefcore)
        +		WRITE_ONCE(cpudata->highest_perf, AMD_PSTATE_PREFCORE_THRESHOLD);
        +	else
        +		WRITE_ONCE(cpudata->highest_perf, AMD_CPPC_HIGHEST_PERF(cap1));
        

        if should look like this:

        +	if (prefcore)
        +		WRITE_ONCE(cpudata->highest_perf, AMD_CPPC_HIGHEST_PERF(cap1));
        +	else
        +		WRITE_ONCE(cpudata->highest_perf, AMD_PSTATE_PREFCORE_THRESHOLD);
        

        There is probably even more wrong, looking at the code quality, but this at least makes the preferred core work.

        • Olissipo@programming.dev
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          1 year ago

          I don’t know if we’re discussing semantics. A performance score is attributed, and before the fix their scores were all 166. It doesn’t work, as you said. So the consequence is the preferred core being “random”, isn’t it?

          • NoXPhasma@lemmy.world
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            1 year ago

            I don’t know if it’s random, the CPU scheduler still decides what thread to use. It will have its own semantics, but I don’t know on what those are based.