CPPC Enabled VS Disabled

Yea the thing that pisses me off is that AMD tried to get CPPC support merged into Linux over 2 years ago but just gave up after the first patchset submitted and no news on it since. Some guy actually ported the original patchset to v5.8 and found some pretty amazing results though it's somewhat bodged.

Hoping that with their refocus on Linux due to Steam's gaming console that they'll get back to CPPC support and eventually get it mainlined. It may not be needed really for Zen 3 (unless you're pushing multi-CCDs like the 5900X/5950X) but it's definitely a benefit to have for Zen 2.

For the Steam Deck, it wouldn't be useful at all since there is only a single CCX and boost is handled differently on mobile parts anyways (boost isn't as high but every core is capable of hitting the advertised clockspeeds, there are no possible latency panalties since there is only a single L3 cache slice, etc.)…

I think the reason why AMD's CPPC implementation wasn't upstreamed into the Linux kernel was that AMD made a vendor- or product-specific implementation instead of following existing kernel infrastructure and paradigms.

Historically, there were separate frequency scaling drivers for every few CPU models in each architecture supported by Linux. It took a long time to get to a generic driver (cpufreq) that worked in a vendor- and architecture agnostic manner and it was needed in order to purge the code duplication and maintenance burden that resulted from the old paradigm.

So instead of adding generic CPPC2 support for cpufreq on X86 (a working implementation is already present for aarch64 and some of the code could be reused), AMD created a vendor specific driver for their own CPUs and called it amd_cpufreq.

The driver was rejected due to the aforementioned reasons and AMD probably figured it was too expensive/not worth the effort to rework it, so they just gave up on the endeavour… Since on 5000 series, all Ryzen APUs (and probably future products too) and 99.99% of Epyc users(!), CPPC isn't needed anymore/at all, I don't think that official support for it will land in cpufreq anytime soon.

Just using the L3$ topology aware ProjectC/PDS (or BMQ) scheduler with an increased kernel tickrate (500hz or higher), voluntary preemption and the 'schedutil' governor on a somewhat recent kernel (IIRC at least 5.10 or 5.11 is needed, earlier versions have to use 'ondemand' due to bugs) yields a consistent performance increase, allowing the CPU to reach its advertised boost speeds and match or exceed the performance of the Windows scheduler that has to misuse CPPC. The performance bump also applies to games btw., as the scheduler "knows" when it makes sense to put threads onto the same CCX in order to benefit from the reduced latency that results from sharing the same block of L3$ and when not.

C0 is active state aka "core is doing work". You disable C6 (core parking) and IF sleep mode via disabling "Global C-State Control". This means that there is less latency associated with handing work to an idle core.

Disabling Cool n' Quiet on the other hand just wastes electrical energy by preventing downclocking of inactive cores and can thereby negatively affect the boost clocks you achieve on active cores (esp. on Ryzen 3000). Ramping clock speeds is fast enough since 3000 series, so CnC can be left enabled.

C6, my bad.

The difference in wattage used with PSS enabled / disabled is only 10W. I do this with a manual OC where my clock does not boost like it does with the default clock & PBO enabled.. so it's beneficial.

I'm not worried about an extra 10W at idle, I think I can spare the couple of extra dollars per month lol.

also disabling Spread Spectrum will ensure that you're using the complete clock speed entered & ensure that BCLK is at 100

Could you plz explain why?

Spread spectrum is a feature of motherboards that is required to pass some safety rules defined by the FCC. Basically it slightly reduces the base clock speed (usually to around 98.8 MHz) to avoid some EMI interference which can affect some things like pacemakers or sensitive electronics in the area.

With it disabled, clocks aren't reduced (therefore increasing EMI) and it increases performance. The base clock is the "fundamental" clock in an operating system and many things are derived from it based on a multiplier, including the CPU, RAM, PCIe speeds.

Say for example your CPU boosts up to 3.6 GHz, the multiplier for that is x36 and is based off the BCLK which is usually 100 MHz (36 x 100 = 3600 MHz). If you had spread spectrum enabled, your BCLK may drop to 98.8 MHz or so, so in actuality your processor's real speed drops from 3.6 GHz to 3.556 GHz (36 x 98.8 = 3556.8 MHz).

Cppc is Auto enabled on Most Mainboards.. togheter with the Standart balanced powerplan

AMD said on Zen 3 which OP uses you only need to use Microsoft's build in power plans..

Ok my mistake as using Zen 2