Can someone explain what the difference is between processor.max_cstate vs intel_idle.max_cstate? And what values are supported?

Most websites show either setting the value as 0 or 1. On my system, without a value set, /sys/module/intel_idle/parameters/max_cstate reports a value of 9.

So assuming 0 though 9 are accepted values, how do they compared to Intel's values of C0, C1, C1E, C2, C2E etc....

Hi:

When you set processor.max_cstate=0, the kernel actually silently sets it to 1.

Maybe these links will help:-
http://www.breakage.org/2012/11/14/p...u_dma_latency/

http://stackoverflow.com/questions/2...sable-c-states

I don't know what values are supported because I don't know what drivers are used to work with intel_idle, the kernel and furthermore the driver for the intel_idle ignors the user's BIOS configuration for the C-states and dances to its own tune. So I don't know how one would get around that.

Setting intel_idle.max_cstate to zero will either revert your cpuidle driver to acpi_idle (at least per the documentation of the option), or disable it completely.
If you have the time do some testing to see the results that you get but be careful and take your time. If you are not sure by all means don't change anything in the /etc/default/grub config:- GRUB_CMDLINE_LINUX_DEFAULT until you have complete confirmation.

http://stackoverflow.com/questions/1...-linux-kernels

Good luck to you and Merry Christmas.
HTH

Here I found a list of all of the C states but wasn't able to find a list of 0 to 9 to compare.
https://gist.github.com/wmealing/2dd2b543c4d3cff6cab7

http://www.linuxtopia.org/online_boo...tion/re90.html

Try this for a google search:
"how do the values of processor.max_cstate compare to intel_idle.max_cstate" is all I can think of.

I have a couple of machines that freeze up. One seems to freeze up anywhere from 1 minute to a day or two after boot. The other seems to run fine for weeks before freezing.

On the machine that freezes sooner, I've been testing the intel_idle.max_cstate=x by adding the kernel parameter just before boot. I've been testing each value for about 4 days. I started with 1, I'm currently on 3. I can't say what's changed between values 1 and 2, but with 3, the CPU is now scaling back the MHz to it's lowest when idle.

I'm not sure in which kernel the intel_pstate driver became the default, but I believe this is when the freezing issue has started. Rather than disable it, I'll test the cstate settings since the machine isn't doing anything important.

Does the pc still freeze when set to 3?

It's possible that you may not have enough RAM:-

Actually it did freeze when set to 3. I've already tested the ram and updated the BIOS. The machine only has 4 GB of non-upgradeable ram. But I've been letting it sit idle, so it hasn't even been using more than 1gb of ram. I've also set a 8gb swap file too.

What kind of age do these machines have?

The 'top' cmd will show you CPU and Swap usage. Maybe check and see if swap is at an ultimate high.
The 8 GB swap file that you made should be of some use.

Are you suspicious of overheating?

Are either one of the machines overclocked?

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Years ago I had an old Toshiba laptop that had Windows Vista on it and long story short I installed Crunch Bang and Linux Mint on it.

The boot process with both distro's would only load about 1/2 way and freeze. Nothing I passed to the kernel worked or put an end to the freezing. At first I thought it was the HDD. As it turned out after disassembly of the laptop the HDD worked fine in the new desktop that I custom built.

I think it was the graphics card on it's way out.

Both machines are Lenovo laptops. The older one is probably no more than 3 years old. I've been monitoring with 'htop'. I'm thinking it's something with the newer kernels and maybe newer Intel chips. They didn't have issues before. I've noticed Ubuntu users reverting to whatever kernel came with 14.04 due to similar issues. My 4790k machine doesn't seem to suffer from this issue, but I haven't fully updated it in a while. It's still running kernel 4.2.3.-1, while the laptops are on 4.7.x-x.

1 members found this post helpful.

Ditto:-
Other than that it might be a hardware issue.

The current stable kernel should have support for the newer Intel chips. (I'd think)
If not than that would be kernel regression.

https://www.kernel.org/

Sometimes recompiling the kernel makes things go away. You could try that to if your up for the task.

Maybe roll back to an older kernel on the laptops and see if the freezing stops.

CTRL+ALT+BACKSPACE kills the X11 interface and restarts it. ( not sure if that helps)
http://unix.stackexchange.com/questi...esktop-freezes

http://askubuntu.com/questions/76073...n-ubuntu-16-04

Make sure the laptops aren't overheating.
Look in the dmesg log it may reveal a clue.