I am running a Intel 10th Gen Xeon W-1290P Comet Lake CPU]. The CPU is really similar to the normal desktop i9-10900k.
The machine containing the CPU runs a Proxmox Hypervisor with Linux kernel 5.11.
root@server:~# uname -a Linux server 5.11.21-1-pve #1 SMP PVE 5.11.21-1~bpo10 (Wed, 02 Jun 2021 11:34:45 +0200) x86_64 GNU/Linux
Energy usage is important to me, so I tried to verify that my system uses C-States to save as much power as possible. While investigating, I found that my system does not use any C-States deeper that C3.
I wanted to find out why my system does not use deeper C-Sates, such as C6, C7 and so on.
Querying sysfs for the max_cstate shows a value of 9.
root@server:~# cat /sys/module/intel_idle/parameters/max_cstate 9
Using the cpupower utility, I got some additional information on the available C-States.
root@server:~# cpupower idle-info CPUidle driver: intel_idle CPUidle governor: menu analysiere CPU 0: Number of idle states: 4 Available idle states: POLL C1_ACPI C2_ACPI C3_ACPI POLL: Flags/Description: CPUIDLE CORE POLL IDLE Latency: 0 Usage: 1012041 Duration: 3293515 C1_ACPI: Flags/Description: ACPI FFH MWAIT 0x0 Latency: 1 Usage: 1340146 Duration: 215843217 C2_ACPI: Flags/Description: ACPI FFH MWAIT 0x33 Latency: 151 Usage: 949495 Duration: 949112994 C3_ACPI: Flags/Description: ACPI FFH MWAIT 0x60 Latency: 1034 Usage: 315636 Duration: 1552349782
Running cpupower idle-info clearly shows, that intel_idle is used as the idle driver. Strangely, it also shows that my system only supports 4 idle states, and they are named C1_ACPI, C2_ACPI, ... instead of C1, C2 and so on.
I also verified that my system uses intel_pstate as the scaling driver.
root@server:~# cpupower frequency-info analysiere CPU 0: driver: intel_pstate Folgende CPUs laufen mit der gleichen Hardware-Taktfrequenz: 0 Die Taktfrequenz folgender CPUs werden per Software koordiniert: 0 Maximale Dauer eines Taktfrequenzwechsels: Cannot determine or is not supported. Hardwarebedingte Grenzen der Taktfrequenz: 800 MHz - 5.30 GHz mÃ¶gliche Regler: performance powersave momentane Taktik: die Frequenz soll innerhalb 800 MHz und 5.30 GHz. liegen. Der Regler "powersave" kann frei entscheiden, welche Taktfrequenz innerhalb dieser Grenze verwendet wird. current CPU frequency: Unable to call hardware current CPU frequency: 4.90 GHz (asserted by call to kernel) boost state support: Supported: yes Active: yes
Why is my system not supporting deeper C-States, like C6? Is there anything I can do to change this? Why are the C-States named C3_ACPI instead of C3 on my system?
Thank you for joining the Intel community
In regards to your question, we would like to encourage you to post the technical information you are looking for in the following community site:
They can help you with additional questions about Intel Xeon W Embedded Processors.
Also, if you already know the FAE ( Field Application Engineer ) that corresponds to you, you can contact them to gather more details.
Have a great day.
Intel Customer Support Technician
For firmware updates and troubleshooting tips, visit: