AMD P-State EPP Driver Updated For Improving Linux Power Efficiency

[NateHubbard]

If you have or can find an example of "ondemand" resulting in smaller power consumption (by more than just 1 Watt) compared to "performance" when the CPU is idle, then please post the example here.

How about I just post today's article where the charts show that very thing?

https://www.phoronix.com/review/ryzen7950x-cpufreq-pstate

[MastaG]

So if I'd like to give this a test on my zen2 threadripper, I should put: initcall_blacklist=acpi_cpufreq_init and amd_pstate.epp_enabled=1

And then simply load the amd_pstate driver and switch to the performance governor.

The last time I've tried it, I also needed the amd_pstate.shared_mem=1 flag.

[arQon]

Any program that contains short bursts of parallel executions (such as: the program is running multiple background jobs and a background job takes less than 100 milliseconds to complete) will be severely slowed down by "ondemand" scheduling.

You say that like it's a bad thing, but that's actually the behavior I *want* out of ondemand. One could even argue that it's the whole *point* of it.

While in an ideal world it would generally be *nice* if it boosted the CPU quickly enough to change state for that and then change back again as quickly when finished with it, that just isn't a significant workload.
Admittedly, the concern is really about heat rather than power usage, and this particular case is almost implicitly short-enough bursts that a heatsink would simply be able to absorb the load without triggering a heightened response from the rest of the system, but even so, this behavior - or at least, some variation of it - is literally the whole point of powersave.

As NateHubbard says, I can trivially see the impact of ondemand on the draw out of the UPS (+18W for something simple like FLAC->MP3), so I don't understand what your other claim is supposed to be about, unless it's specific to Zen3?

[syrjala]

Yeah. and DRI was a thrash band. For them, the resolution of the acronym was https://en.wikipedia.org/wiki/Dirty_Rotten_Imbeciles

The band seems to be "D.R.I." assuming one can trust wikipedia.

I was a bit curious which came first DRM="Direct Rendering Manager" or DRM="Digital Rights Management", and so far it looks like a pretty close race.
The first mention of the "Digital Rights Management" variety I found was some Microsoft patent from 1999, while Precision Insight presented the DRI design to the public in 1999 as well.

"DRM" appeared quite a few times in older patents too, but it always meaning something totally different. And "digital rights management" was mentioned at least in some 1998 patents but didn't seem to get shortened to "DRM" at that point.