Date: Mon, 25 May 2026 17:34:39 +0200 From: Olivier Certner <olce@freebsd.org> To: Chris Torek <chris.torek@gmail.com> Cc: Warner Losh <imp@bsdimp.com>, Adrian Chadd <adrian@freebsd.org>, freebsd-current <freebsd-current@freebsd.org>, ShengYi Hung <aokblast@freebsd.org> Subject: Re: AMD, CPPC, etc Message-ID: <11798552.X2hNYcAVgp@ravel> In-Reply-To: <CAPx1GvdM3yUK9vpTLYwE4yXm7R0Vzea96xAsPPrNZmEHqeb8-Q@mail.gmail.com> References: <CAPx1GvfaDdmj0vkzzinyhGm2mQRKgmOh3fpNXo-cgznoujVY-Q@mail.gmail.com> <CANCZdfoyqdEr_1%2Bkmi5_0TTG0VaAZMjXgGOubWt5nVK8aqe9DQ@mail.gmail.com> <CAPx1GvdM3yUK9vpTLYwE4yXm7R0Vzea96xAsPPrNZmEHqeb8-Q@mail.gmail.com>
index | next in thread | previous in thread | raw e-mail
[-- Attachment #1 --]
> On my desktop system, using 0 ("auto") mode works quite well: the
> system idles around 80 to 95 watts, and when building ports or
> /usr/src with all 32 CPUs going, gets up to the 320-watt range, all
> without any OS work required.
What's the EPP value you are using? The default of 0?
Now, the question is: Do you get the same performance with these more power-flexible settings compared to the driver's defaults (which are desired performance set to maximum performance (which reported value do you see for that?) and EPP to 0) when building ports or src on the 32 cores?
> I'm not sure what actually chooses the CPU frequency here.
In auto-mode, the cores auto-tune themselves, so basically a hardware governor is at play.
I suggest you forget about actual frequencies, CPPC can be finer-grained than that, with hardware leveraging other performance mechanisms, even if it seems that, currently, on AMD hardware, performance levels are achieved only through changing frequency.
Regards.
--
Olivier Certner
[-- Attachment #2 --]
-----BEGIN PGP SIGNATURE-----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=Wogx
-----END PGP SIGNATURE-----
home |
help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?11798552.X2hNYcAVgp>