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I FIXED AMD's Preferred Core Linux patch to FINALLY work for HIGHER BOOST and PERFORMANCE ! (www.youtube.com)
submitted 1 year ago by trclst@lemmy.ml to c/linux@lemmy.ml
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[-] NoXPhasma@lemmy.world 9 points 1 year ago* (last edited 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 2 points 1 year ago* (last edited 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 1 points 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.

this post was submitted on 28 Aug 2023
264 points (94.3% liked)

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