The Impact Of The CPU Frequency Scaling Governor On AMD Threadripper 2990WX Linux Performance

[phoronix]

Phoronix: The Impact Of The CPU Frequency Scaling Governor On AMD Threadripper 2990WX Linux Performance

One of many test requests we have received concerning the AMD Threadripper 2 Linux performance was to look at the impact of the different CPU frequency scaling governors, particularly for the 32-core / 64-thread Ryzen Threadripper 2990WX. Here are those CPUFreq governor benchmarks for those interested in squeezing slightly better performance out of your HEDT system by changing how aggressively or not the system is shifting power states to higher frequencies.

http://www.phoronix.com/vr.php?view=26752

[Zola]

Interestingly enough conservative did work rather well, especially compared to ondemand. Would be interesting to see if it saves any power.

[willmore]

If the 'conservative' governor does better than the others it's likely an example of a task that doesn't make full use of all cores (either because of design or CPU constraints) as it lets unused cores clock down and save power (thus reducing heating) and letting other cores run faster.

[MadCatX]

What I find most interesting is the behavior of "smart" schedulers with x264 and x265 workload where switching to "performance" yields significant performance boost. I remember that the x264 encoding was one of the few tests where Windows 10 managed to edge out Linux and I wonder if this could be the reason behind it. Anyway, thanks for the benchmark Michael and enjoy a small PayPal tip...

[cj.wijtmans]

you didnt test with cpufreq off.

[wpupkin]

For those wondering (schematic behaviour, cpufreq on AMD):

• conservative : min -> mid -> max -> mid ->min
• ondemand: min -> max -> mid -> min
• performance: max
• powersave: min
• schedutil: magic

This for all ever CPU Frequency Scaling Governor On AMD Impact tests

[busukxuan]

• schedutil: magic

That!

[davidbepo]

quite disappointing to see ondemand beating schedutil, anyway this cpu is weird so i wouldnt really try to extract conclussions

[gmturner]

AMD seems to be implementing their aggressive scheduling magic at the platform level, analogous to Intel's "SpeedMax" or whatever... I wonder if all this is ignored by Linux, if Linux is an automatic beneficiary of it, or what? Since I plan to make myself a victim of X399 in the near future, it sure looks like I will have some reading to do...

[GreenReaper]

Performance isn't just about raw performance, it's latency. I saw significant improvements in nginx/PHP response times when using the performance governor, presumably because it kept CPUs at a higher frequency and was faster to ramp it up (as verified by turbostat in Debian's linux-cpupower package).

Power usage increased as well, but it was still less than if the CPU had C-states turned off (because switching some cores into idle allows the others to boost), as well as performing better.