Date: Mon, 27 Jan 2020 19:15:45 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 234733] Setting CPU frequency with sysctl dev.cpu.0.fr slows a Ryzen 2700X down Message-ID: <bug-234733-227-HbOWVEoLLp@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-234733-227@https.bugs.freebsd.org/bugzilla/> References: <bug-234733-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D234733 --- Comment #21 from Conrad Meyer <cem@freebsd.org> --- (In reply to sigsys from comment #20) c0010061 doesn't follow c00l0062 on my Zen1 + ASRock X370 system, for examp= le. :-) Maybe it's a Zen+ thing, maybe it's a BIOS thing, who knows. In any case I agree we don't really understand what it does. It doesn't se= em to line up with the documentation, and I don't expect ignoring it to be har= mful to modern AMD hardware for power/thermal reasons. (I expect HW made in the last ten years to thermal throttle regardless of SW-set P-state. My concern around removing it entirely, as Linux seems to, is mostly that doing so mig= ht be harmful for the older CPUs this driver supports (k10, k11). But -- clea= rly not a problem for Linux.) I like your suggestion of a sysctl/tunable. I propose defaulting to "ignore c0010061." I am having trouble coming up with an accurate and descriptive docstring, though. "If set, limit requested P-states to MSR c0010061[0:2]" isn't exactly useful to end users, probably. --=20 You are receiving this mail because: You are the assignee for the bug.=
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