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I'm currently using ubuntu 20.04 on an HPE DL380 Gen10 server. The CPU is using Xeon 4216. The problem is that the CPU in question has a base clock of 2.1GHz.

When checking with Turbostat or cat /proc/cpuinfo, one core body is connected at approximately 800MHz to 1.2GHz.

Checking the test servers used by CentOS, etc. have Olympic verification at 2.1 GHz.

BIOS settings are similar. Even if you set cpufreq, cpupower, etc. in your OS, you're asking it to keep the default clock engaged like Centos. I would like to inquire as to how to access the fixed Base Clock.

What's even more unusual is that the same Ubuntu 20.04 and CPU are used, but the kubernetes service is operated and the base clock of the server is confirmed to be 2.1 GHz, which is inconvenient, and other servers are confirmed because they have clocks. Similarly, BIOS and OS settings are the same.

Cleaning up the environment explains it.

leaf condition ubuntu 20.04 & openstack server: 800MHz~1.2GHz centos 7.9 & openstack server: 2.1GHz ubuntu 20.04 & Kubernetes server: 2.1GHz

  • BIOS & OS settings are the same. Only the service and OS are different.

I would like to play around with the reason or inquire as to whether there is a way to access the Base Clock so that the OS, etc. can handle the Base Clock. As detailed, tuned, cpufreq, cpupower, etc. were not possible.

thank you

pal pay
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1 Answers1

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From your turbostat listing one can observe the your base clock is stable at 2.1 GHz. What you are observing is the processor itself scaling backing off the CPU frequency because your system is very idle. This behaviour is normal. The behaviour can be altered by disabling the C1E idle, if your system has it.

Let's show an example using my i5-10600K processor, with a base frequency of 4.1 GHz:

Note 1: This example is using: The intel_pstate CPU frequency scaling driver; The Powersave CPU frequency scaling governor; HWP enabled (typically this is the default); The TEO idle governor; /sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq is set to the base frequency of 4.1 GHz (it would be 2.1 GHz for your processor).

Note 2: the default kernel for my COMETLAKE processor does not use the C1E idle state. I had to compile a custom kernel for this answer.

Example:

root@s19:/home/doug# turbostat --quiet --show CPU,Busy%,Bzy_MHz --interval 60
CPU     Busy%   Bzy_MHz
-       0.06    4637
0       0.01    3950
6       0.01    3548
1       0.22    4654
7       0.11    4624
2       0.29    4775
8       0.00    2568
3       0.01    3577
9       0.00    3832
4       0.00    3385
10      0.00    3036
5       0.12    4574
11      0.00    3676

Observe the system is very idle, and several listed CPU frequencies are below the specified minimum of 4.1 GHz.

Now identify and disable the idle state that is using C1E:

$ grep . /sys/devices/system/cpu/cpu2/cpuidle/state*/name
/sys/devices/system/cpu/cpu2/cpuidle/state0/name:POLL
/sys/devices/system/cpu/cpu2/cpuidle/state1/name:C1
/sys/devices/system/cpu/cpu2/cpuidle/state2/name:C1E
/sys/devices/system/cpu/cpu2/cpuidle/state3/name:C3
/sys/devices/system/cpu/cpu2/cpuidle/state4/name:C6
/sys/devices/system/cpu/cpu2/cpuidle/state5/name:C7s
/sys/devices/system/cpu/cpu2/cpuidle/state6/name:C8
/sys/devices/system/cpu/cpu2/cpuidle/state7/name:C9
/sys/devices/system/cpu/cpu2/cpuidle/state8/name:C10

Oh, it is idle state 2:

echo 1 | sudo tee /sys/devices/system/cpu/cpu*/cpuidle/state2/disable

And now:

root@s19:/home/doug# turbostat --quiet --show CPU,Busy%,Bzy_MHz --interval 60
CPU     Busy%   Bzy_MHz
-       0.04    4662
0       0.01    4165
6       0.23    4657
1       0.00    4100
7       0.00    4101
2       0.15    4780
8       0.00    4100
3       0.00    4101
9       0.06    4671
4       0.00    4102
10      0.00    4308
5       0.01    4101
11      0.00    4159

Observe the system is till very idle, but the listed CPU frequencies are never below the set minimum of 4.1 GHz.

Doug Smythies
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