Intel Coffee Lake can't get into higher C-states

TrueNAS General
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1

Hi,

I have a problem with achieving higher C-states according to powertop. The maximum what I get i C3 on package (CPU is running on C7).

I recently moved from AMD A8-5545 and now full setup has about 30W with 3HDD and 1SSD for boot. Previously it was about 40W.

I moved to i5-8400 because I plan to use VMs on TrueNAS and i wanted to have more cores. Upgrade was quite cheap (about 50€ for mobo + CPU, another 70€ for 32GB RAM).

Many people have moved to 13th gen (and reporting that ASPM and high C-states work) but I don’t wanna spend such big money.

My current hardware:

ASRock H310CM-DVS (it has Realtek 8111H, which has problems with ASPM, and generally needs to driver change to i8168, because i8169 has strange speed drops)

i5-8400

2x16GB DDR4 2400

1SATA SSD

and 3x 2TB HDD for storage

My question is: Has anyone achieved high C-states on idle on Coffee Lake?

I have an option to move to 10th gen (i3-10100 is pretty cheap with any of H410/H47/H510 mobo), but these motherboards also have Realtek NICs.

I had old intel NIC which uses e1000e driver, but this driver explicitly disables ASPM.

Summarizing:

Realtek NIC - ASPM is disabled

Intel e1000e - ASPM is disabled

If I go for Intel i210 NIC is there a chance for enabling ASPM or the whole problem is the shitty ASRock bios?

What are your thoughts?

Now, bare system pulls about 16W from plug. People who uses 13th gen has 6-7W.

2

if we are talking about Watts, i think, you should think about going SSD…

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3

Yes, but the whole server depends also on rest of platform.

4

And chances are that something in “the rest of the plateform” is holding you to C3. Good luck whacking the mole…
But changing to a cheap motherboard of the next generation with the same crappy components is unlikely to bring a solution.

Note that TrueNAS itself will hold you by keeping the drives spinning.

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5

I found that problem is SSD drive. I turned off Realtek NIC and changed ssd to Crucial I can reach C7 state on package.

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6

So you changed two things…
How can you tell that the problem was caused by the SSD and not the NIC?

Can you already say what impact this deeper C-state has ?
(I’m wondering how much time a TrueNAS system actually spends in deeper C-states, because there is “always something going on”…)

7

First, I turned off realtek NIC because this specific chip has problems with ASPM on linux, even on r8168-dkms driver - no change (tested on Windows, debian, proxmox 9, truenas scale). I tried it initially.

I read something that someone had problems with Intenso SSD drive (that’s generally a cheap drive). So i get Crucial BX500 which was around, installed minimal debian and found that powertop shows high C-states. Doing the same with previous ADATA SU650 C3 is maximum.

Also, i found out that putting this ADATA into USB 3.0 enclosure makes C7 possible.

But, the C-states are not an ultimate measurement. This USB 3.0 enclosure is grabbing 3-4W which were achieved from getting into higher C-states.

Now, i installed TrueNAS on my “primary” boot drive - old Samsung M2 Sata 32GB drive. With the usb 3.0 network card from ugreen I have 12W from plug.

I want to check Intel i210 NIC pci-e card, i will borrow it from my friend and test.

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