@Haw Loeung: In addition to what I wrote earlier:

> With the new Ubuntu archive servers, we saw constantly high load
> and after some tinkering, we found that it was mostly CPUs
> being woken up to see if they should enter idle states.
> Changing the CPU frequency scaling governor to "performance" saw a 
> considerable drop.

What do you mean by "high load"?
And when you say "saw a considerable drop", does that mean in wakeups per 
second or load?

Note that you should observe a significant difference in load average on
a server between powersave and performance mode, and that actually
indicates things are working as they should be. For the SpecPower
simulator test I posted above, I'll add some more data for the 0.5X and
X lines:

0.5X, where Performance used 31.7% more package power:
Powersave: Busy%: 12.58% (load average = 1.01) Bzy MHz: 1651
Performance: Busy%: 5.04% (load average = 0.40) Bzy MHz: 3686

X, where Performance used 42.1% more package power:
Powersave: Busy%: 23.66% (load average = 1.89) Bzy MHz: 1798
Performance: Busy%: 10.56% (load average = 0.84) Bzy MHz: 3681

Isn't energy consumption what really matters, as long as performance doesn't 
suffer too much?
What I would like to see for your servers is the results from:

sudo turbostat -J -S --debug sleep 300

For the intel_pstate CPU frequency scaling driver and the powersave and
performance scaling governors with your work flow.

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  Keep powersave CPU frequency scaling governor for CPUs that support

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