[personal profile] mjg59
(Edit to add: this issue is restricted to the mobile SKUs. Desktop parts have very different power management behaviour)

Linux 4.5 seems to have got Intel's Skylake platform (ie, 6th-generation Core CPUs) to the point where graphics work pretty reliably, which is great progress (4.4 tended to lose all my windows every so often, especially over suspend/resume). I'm even running Wayland happily. Unfortunately one of the reasons I have a laptop is that I want to be able to do things like use it on battery, and power consumption's an important part of that. Skylake continues the trend from Haswell of moving to an SoC-type model where clock and power domains are shared between components that were previously entirely independent, and so you can't enter deep power saving states unless multiple components all have the correct power management configuration. On Haswell/Broadwell this manifested in the form of Serial ATA link power management being involved in preventing the package from going into deep power saving states - setting that up correctly resulted in a reduction in full-system power consumption of about 40%[1].

I've now got a Skylake platform with a nice shiny NVMe device, so Serial ATA policy isn't relevant (the platform doesn't even expose a SATA controller). The deepest power saving state I can get into is PC3, despite Skylake supporting PC8 - so I'm probably consuming about 40% more power than I should be. And nobody seems to know what needs to be done to fix this. I've found no public documentation on the power management dependencies on Skylake. Turning on everything in Powertop doesn't improve anything. My battery life is pretty poor and the system is pretty warm.

The best thing about this is the following statement from page 64 of the 6th Generation Intel ® Processor Datasheet for U-Platforms:

Caution: Long term reliability cannot be assured unless all the Low-Power Idle States are enabled.

which is pretty concerning. Without support for states deeper than PC3, Linux is running in a configuration that Intel imply may trigger premature failure. That's obviously not good. Until this situation is improved, you probably shouldn't buy any Skylake systems if you're planning on running Linux.

[1] These patches never went upstream. Someone reported that they resulted in their SSD throwing errors and I couldn't find anybody with deeper levels of SATA experience who was interested in working on the problem. Intel's AHCI drivers for Windows do the right thing, but I couldn't find anybody at Intel who could get any information from their Windows driver team.
Page 2 of 2 << [1] [2] >>

Date: 2016-04-17 10:51 am (UTC)
From: (Anonymous)
starting with with 4.6-rcmy Haswell mobile i7-4600M refuses to enter PC states lower than pc2 and burning ~18 Watts when idle (~11 Watts with 4,5). seems that intels pstate changes merged into 4.6 messed things up big time! :(

Date: 2016-04-17 03:32 pm (UTC)
From: (Anonymous)
Same for my Skylake system! It could reach PC3, but on 4.6-rc3 - PC2 only

Date: 2016-04-17 03:58 pm (UTC)
From: (Anonymous)
It is a known regression - https://bugzilla.kernel.org/show_bug.cgi?id=115771. You could try to apply V5 patch from comment https://bugzilla.kernel.org/show_bug.cgi?id=115771#c106, it helped me a lot.

Two questions?

Date: 2016-04-17 03:37 pm (UTC)
From: (Anonymous)
Bad news for me cause I wanted to buy i3-6100u laptop as [long term] Linux machine.
Got two questions:

1. How to check from system if above problem occur on my machine/linux system, what command to use?
2. Are all Skylake ULV chips affected, what about Pentiums, f.e. Pentium 4405U maybe they haven't got some problematic sleeps states, maybe they are cut for the budget sake?

Date: 2016-04-17 07:56 pm (UTC)
From: [personal profile] edmonds
This is from an Ubuntu Edition Dell XPS 13 9350 (i7-6560U), running BIOS 1.3.3.

powertop: http://paste.debian.net/plain/437840

lspci: http://paste.debian.net/plain/437841

It looks like it manages to reach PC8 some small amount of the time. But this system experiences GPU hangs in this configuration unless I boot with i915.enable_rc6=0.

I'm running Debian's kernel 4.6~rc3-1~exp1 and xserver-xorg-video-intel 2:2.99.917+git20160325-1, with latest i915 firmware from https://01.org/linuxgraphics/intel-linux-graphics-firmwares and iwlwifi firmware from http://git.kernel.org/cgit/linux/kernel/git/iwlwifi/linux-firmware.git.

Date: 2016-04-18 09:00 pm (UTC)
From: (Anonymous)
Found something interesting here http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/desktop-6th-gen-core-family-spec-update.pdf
SKL083 - The Processor May Fail to Properly Exit Package C6 or Deeper
Maybe microcode disables such states because of this bug?

Regression from 4.4?

Date: 2016-04-18 11:07 pm (UTC)
From: (Anonymous)
This seems like a regression to me. With 4.4.6, the CPU spends a significant amount of time (50+ percent) in PC8 and PC6. With 4.6-rc3, it very rarely reaches even PC3 (and never anything deeper than that), and when it does the screen starts randomly blacking out for short intervals. This is on a ThinkPad T460 with an i5 6300u.

Re: Regression from 4.4?

Date: 2016-04-23 04:11 pm (UTC)
From: (Anonymous)
I'm seeing this as well on a Dell xps-13 9350 with debian kernels 4.4 and 4.5 - spends 60% of time in pc8 on 4.4 and initially also on 4.5, but after X login 4.5 spends all of its time in pc2/3.

I don't have graphics problems and don't use suspend/hibernate.

further advice required

Date: 2016-04-21 07:06 am (UTC)
From: (Anonymous)
could you be more specific on effects ie battery life? say windows gets 9 hours what could one expect on the latest kernel? i note that Dell already ships ubuntu with skylake and would find it therefore surprising if impact was really so bad. (im not interested in long term life)

The reason is iGPU

Date: 2016-04-23 12:50 pm (UTC)
From: (Anonymous)
it seems that the reason for not reaching PC6+ is iGPU. I've updated my system to kernel from https://cgit.freedesktop.org/drm-intel/log/?h=drm-intel-next to fix screen flickering, and also applied patch from http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ffb810563c0c049872a504978e06c8892104fb6c (which is a regression fix for kernel 4.6), and now I'm mostly in PC6 and PC8. Also, turbostat showing that GPU frequency is mostly 300MHz, whereas it was more higher on vanilla 4.5.0 and 4.6.0-rc3, so it seems that it was the reason why he whole packages cannot reach states deeper than PC3.

P.S. Applying regression fix only is not enough - it's a drm-intel-next which contains main fix.

Re: The reason is iGPU

Date: 2016-04-24 12:12 pm (UTC)
From: (Anonymous)
I've just rebuilt from the drm-intel-next git + your suggested patch and I still can't get lower than PC3, do you have more information about your hardware?

Re: The reason is iGPU

From: (Anonymous) - Date: 2016-04-26 07:12 pm (UTC) - Expand

Re: The reason is iGPU

From: (Anonymous) - Date: 2016-04-27 05:48 am (UTC) - Expand

Re: The reason is iGPU

From: (Anonymous) - Date: 2016-04-27 06:52 am (UTC) - Expand

XPS 15 9550

Date: 2016-04-24 03:24 pm (UTC)
From: [personal profile] bradlaue
With the NVMe drive. Interested in a challenge, I installed Gentoo on the machine - configuring the kernel with intel_idle and enabling ACPI / tuning power management according to various sources of documentation doesn't get me past PC3.

Using Fedora 23 (installed from a respin as the original 4.2 kernel can't make it through the install process) powertop reports the Package entering PC8 though.

An earlier post of yours indicates multiple subsystems like SATA and I2C have to succeed in entering a power saving state before the entire Skylake package itself will also. My nearest guess so far is that's related?

EDIT: Actually your earlier post was related to haswell/broadwell. My mistake!

I assume you're also using Fedora 23 though, which makes it doubly mysterious.
Edited Date: 2016-04-24 03:26 pm (UTC)

Re: XPS 15 9550

Date: 2016-04-24 09:20 pm (UTC)
From: (Anonymous)
I was referring to a Skylake platform though, I suppose I replied to the wrong thread. I have a XPS 13 9350

HP laptops

Date: 2016-04-25 10:22 pm (UTC)
From: (Anonymous)
Don't ever buy them - this company doesn't give a fuck about the end user. No BIOS updates, nothing.

And PC8 sleep state is obviously not supported on HP Skylake laptops. Do not expect a BIOS fix or anything. Your support requests will be ignored (I've filed three already - no results).

Dell Precision 5510, i7-6820HQ, Fedora 23

Date: 2016-05-05 12:09 pm (UTC)
From: (Anonymous)
Dell Precision 5510 ( pretty much the same as the XPS15)
i7-6820HQ,
Samsung M.2 PM971 (NVMe)
Fedora 23, Rawhide kernel - 4.6.0-0.rc6.git1.1.fc25.x86_64

I was only getting to c3 ( package ), but managed to get to C8 by disabling the Nvidia Quadro, once I found out where to get bbswitch-dkms from

https://fedoraproject.org/wiki/Bumblebee

For anyone wanting to repeat ..

dnf -y --nogpgcheck install http://install.linux.ncsu.edu/pub/yum/itecs/public/bumblebee/fedora23/noarch/bumblebee-release-1.2-1.noarch.rpm
dnf install bbswitch-dkms
modprobe bbswitch
echo OFF > /proc/acpi/bbswitch

Package
C2 (pc2) 4.8%
C3 (pc3) 2.6%
C6 (pc6) 3.9%
C7 (pc7) 0.0%
C8 (pc8) 18.4%
C9 (pc9) 0.0%
C10 (pc10) 0.0
From: (Anonymous)
Thank you for this article. I wish I had read it BEFORE I bought my new computer. Why doesn't Intel provide info on how to fix this? I mean, if I understand you right they even made the drivers for windows, not only helped the folks at Microsoft. So at least they should provide the necessary info so other people who don't want to run Windows can create the required drivers for their OSes, too.

Right now I'm thinking about turning the bought computer back in, and choose another one, then maybe without Intel inside. At least one thing's for sure: I will be VERY careful next time when looking for a new computer, and if Intel doesn't change their policy about support for other OS this will have been the last Intel product I've ever purchased.

4.6 seems to have better support

Date: 2016-05-30 10:01 pm (UTC)
From: (Anonymous)
I have a Thinkpad X1 Carbon (4th gen). I'm running debian sid with 4.5 kernel. It seems that I couldn't get past PC2. I've updated my kernel to the latest in experimental which is 4.6 and I'm reaching PC8.

C2 (pc2) 12.2%
C3 (pc3) 0.2%
C6 (pc6) 39.4%
C7 (pc7) 0.0%
C8 (pc8) 14.1%
C9 (pc9) 0.0%
C10 (pc10) 0.0%

I've also flashed the BIOS to the latest version:

BIOS Revision: 1.14 Firmware Revision: 1.9

microcode revision=0x88.

I'm not sure if the BIOS/firwmare/microcode upgrade made any real difference or if it was just the kernel because it did reach PC8 with just the kernel upgrade.

Hopefully this will improve the battery life a bit.

Re: 4.6 seems to have better support

Date: 2016-06-09 06:55 pm (UTC)
From: (Anonymous)
IT WAS THE IMEI FIRMWARE!

So I Think I was experiencing the same thing. I'm still running 4.4.0-23 *(ubuntu kernel). I was only able to get to pc2. I ended up booting into windows to debug a separate unrelated issue, and ran a few updates. I had already been running the 1.14 bios and firmware revision 1.9 so that wasn't the solution. I did upgrade the IMEI firmware though. After rebooting back into linux I'm now getting much better behavior.

C2 (pc2) 12.6%
C3 (pc3) 0.1%
C6 (pc6) 55.4%
C7 (pc7) 0.0%
C8 (pc8) 14.8%
C9 (pc9) 0.0%
C10 (pc10) 0.0%

It's worth noting that I am using an NVMe drive so the sata patches here don't apply.

Re: 4.6 seems to have better support

From: (Anonymous) - Date: 2016-06-22 05:26 am (UTC) - Expand

Re: 4.6 seems to have better support

From: (Anonymous) - Date: 2016-06-29 10:33 pm (UTC) - Expand

Re: 4.6 seems to have better support

From: (Anonymous) - Date: 2016-07-14 10:10 pm (UTC) - Expand

Re: 4.6 seems to have better support

From: (Anonymous) - Date: 2016-07-17 09:01 pm (UTC) - Expand

average battery life on T460s

Date: 2016-07-17 02:04 pm (UTC)
From: (Anonymous)
How long lasts your battery (on your T460s) after performing the mentioned optimizations ?

Kernel 4.7 seems to do PC8 OK

Date: 2016-07-26 12:29 am (UTC)
From: (Anonymous)
Another data point, FWIW: vanilla kernel 4.7 seems to go to PC8 OK. I didn't see PC8 on 4.5 or 4.6.

Dell XPS 13 9350, 1.4.0 BIOS, Intel WiFi. The only change from kernel defaults is i915.enable_rc6=1.

Idle-ish system with normal processes running, screen on:

C2 (pc2) 18.5%
C3 (pc3) 0.3%
C6 (pc6) 2.5%
C7 (pc7) 0.0%
C8 (pc8) 36.6%
C9 (pc9) 0.0%
C10 (pc10) 0.0%

If I quit Firefox then PC8 goes up to around 50%.

Full PowerTOP bits: https://gist.github.com/projectgus/e79923530392517c4e55064bb07b778d

(On the offchance anyone sees this and decides to buy an XPS 13 on this basis - it's still been a trip back to running Linux 10-15 years ago. I get random hard locks coming out of suspend, screen flickers when the laptop gets hot, glitchy touchpad driver, USB Type C is WIP, etc. Have spent way too much time compiling kernels and trawling forums. I wish I'd done my homework beforehand instead of thinking "well, Dell ships Linux on it from factory. How bad can it be?")

Re: Kernel 4.7 seems to do PC8 OK

Date: 2016-07-27 12:16 pm (UTC)
From: (Anonymous)
Although there is nothing specific for Skylake, perhaps this will help (in kernel 4.8) ?
https://www.phoronix.com/scan.php?page=news_item&px=Linux-4.8-Power-Management-ACPI

Update?

Date: 2016-09-14 11:18 pm (UTC)
From: (Anonymous)
Any update since you first installed? There have been a few kernel releases since then. I was going to install Fedora 24 or Debian, thoughts?

Interesting news?

Date: 2016-09-18 08:11 pm (UTC)
From: (Anonymous)
Just bought a ThinkPad E460 (i5-6200U, regular SATA drive): enabling everything in the "Tunables" list of powertop, I get up to C10 for all cores, but PC7 only for the package. I'm on Arch, and I've also tried the latest linux-git kernel (4.8.0-rc6).

BTW, just have a look at table 4-4, page 70 of [1]: having a FHD screen that does NOT support PSR ([drm:intel_psr_enable] PSR not supported by this panel in kernel log), without turning off the screen, my max package state is actually PC8!

So, any thoughs to level up from PC7 to PC8?


[1] http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/6th-gen-core-family-mobile-u-y-processor-lines-datasheet-vol-1.pdf

Re: Interesting news?

Date: 2016-09-23 07:21 pm (UTC)
From: (Anonymous)
I've found that some of devices (either smartcard reader or cardreader) prevents my T460s eneter PC8. You could disable every unneeded device in BIOS and check if it'll help. Also, you'll probably need to enable ALPM on your SATA controller

Re: Interesting news?

From: (Anonymous) - Date: 2016-09-24 07:55 pm (UTC) - Expand

Lenovo Yoga 900

Date: 2016-10-09 11:04 am (UTC)
From: (Anonymous)
Currently at kernel 4.8.1, there is still no difference for the Lenovo Yoga 900.

Version:
➜  ~ uname -a
Linux V 4.8.1-040801-generic #201610071031 SMP Fri Oct 7 14:34:10 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux


Output of powertop:
          Package   |             Core    |            CPU 0       CPU 2
C2 (pc2)   33.2%    |                     |
C3 (pc3)    0.0%    | C3 (cc3)    0.9%    | C3-SKL      1.0%    0.3 ms  1.0%    0.4 ms
C6 (pc6)    0.0%    | C6 (cc6)    6.0%    | C6-SKL      8.2%    0.6 ms  4.5%    0.7 ms
C7 (pc7)    0.0%    | C7 (cc7)   35.0%    | C7s-SKL     0.1%    1.1 ms  0.1%    1.6 ms
C8 (pc8)    0.0%    |                     | C8-SKL     23.8%    1.7 ms 22.9%    3.2 ms
C9 (pc9)    0.0%    |                     | C9-SKL      0.0%    2.5 ms  0.0%    0.7 ms
C10 (pc10)  0.0%    |                     | C10-SKL    17.4%    3.9 ms 54.8%   10.6 ms


The bits [2:0] are set to 1, so should BIOS does not deny access to enter PC states. The MSR value is not at fault.
➜  ~ sudo rdmsr 0xE2
1e008006


Driver in use: intel_idle
➜  ~ grep . /sys/devices/system/cpu/cpuidle/*
/sys/devices/system/cpu/cpuidle/current_driver:intel_idle
/sys/devices/system/cpu/cpuidle/current_governor_ro:menu


➜  ~ dmesg | grep -i error
[    3.283699] EXT4-fs (sda9): re-mounted. Opts: errors=remount-ro
[    3.487043] iwlwifi 0000:01:00.0: Direct firmware load for iwlwifi-8000C-24.ucode failed with error -2
[    3.487054] iwlwifi 0000:01:00.0: Direct firmware load for iwlwifi-8000C-23.ucode failed with error -2
[    3.487145] iwlwifi 0000:01:00.0: Direct firmware load for iwlwifi-8000C-22.ucode failed with error -2
[    3.852964] i2c_hid i2c-ITE8396:00: error in i2c_hid_init_report size:19 / ret_size:18


Bug opened and hijacked: https://bugzilla.kernel.org/show_bug.cgi?id=116591

Duplicate bug opened: https://bugzilla.kernel.org/show_bug.cgi?id=116671. Just refers to https://github.com/mjg59/linux/tree/sata-lpm-firmware.

I think I've to conclude that nobody seems to be working on it.

Re: Lenovo Yoga 900

Date: 2016-10-09 11:19 am (UTC)
From: (Anonymous)
I stand corrected

   Bad           VM writeback timeout                                                                                   
   Bad           Enable SATA link power management for host0
   Bad           Enable SATA link power management for host1
   Bad           Enable SATA link power management for host2
   Bad           Enable Audio codec power management
   Bad           NMI watchdog should be turned off
   Bad           Runtime PM for I2C Adapter i2c-1 (i915 gmbus dpb)
   Bad           Runtime PM for I2C Adapter i2c-2 (i915 gmbus dpd)
   Bad           Runtime PM for I2C Adapter i2c-0 (i915 gmbus dpc)
   Bad           Autosuspend for unknown USB device 1-7 (8087:0a2b)
   Bad           Runtime PM for PCI Device Intel Corporation Sky Lake Integrated Graphics
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP HD Audio
   Bad           Runtime PM for PCI Device Intel Corporation Sky Lake Host Bridge/DRAM Registers
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP Thermal subsystem
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP SMBus
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP LPC Controller
   Bad           Runtime PM for PCI Device O2 Micro, Inc. Device 8620
   Bad           Runtime PM for PCI Device Intel Corporation Skylake Processor Thermal Subsystem
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP CSME HECI
   Bad           Runtime PM for PCI Device Intel Corporation Wireless 8260
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP PMC
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode]


Changing to:

   Good          VM writeback timeout
   Good          Enable SATA link power management for host0
   Good          Enable SATA link power management for host1
   Good          Enable SATA link power management for host2
   Good          Enable Audio codec power management
   Good          NMI watchdog should be turned off
   Good          Runtime PM for I2C Adapter i2c-1 (i915 gmbus dpb)                                                      
   Good          Runtime PM for I2C Adapter i2c-2 (i915 gmbus dpd)
   Good          Runtime PM for I2C Adapter i2c-0 (i915 gmbus dpc)
   Bad           Autosuspend for unknown USB device 1-7 (8087:0a2b)
   Good          Runtime PM for PCI Device Intel Corporation Sky Lake Integrated Graphics
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP HD Audio
   Bad           Runtime PM for PCI Device Intel Corporation Sky Lake Host Bridge/DRAM Registers
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP Thermal subsystem
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP SMBus
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP LPC Controller
   Bad           Runtime PM for PCI Device O2 Micro, Inc. Device 8620
   Bad           Runtime PM for PCI Device Intel Corporation Skylake Processor Thermal Subsystem
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP CSME HECI
   Bad           Runtime PM for PCI Device Intel Corporation Wireless 8260
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP PMC
   Bad           Runtime PM for PCI Device Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode]


Allows the chip (peripherals) to spend time in lower power states than pc2:

          Package   |             Core    |            CPU 0       CPU 2
                    |                     | C0 active   1.7%        1.2%
                    |                     | POLL        0.5%    2.6 ms  0.0%    0.0 ms
                    |                     | C1E-SKL     4.3%    2.0 ms  0.3%    0.3 ms
C2 (pc2)   11.5%    |                     |
C3 (pc3)    0.3%    | C3 (cc3)    0.1%    | C3-SKL      0.1%    0.1 ms  0.1%    0.2 ms
C6 (pc6)    2.4%    | C6 (cc6)    1.9%    | C6-SKL      2.0%    0.5 ms  3.8%    1.9 ms
C7 (pc7)    0.1%    | C7 (cc7)   37.4%    | C7s-SKL     0.0%    0.0 ms  0.0%    0.0 ms
C8 (pc8)   20.7%    |                     | C8-SKL      9.4%    1.3 ms 11.6%    5.1 ms
C9 (pc9)    0.0%    |                     | C9-SKL      0.0%    0.0 ms  0.0%    0.0 ms
C10 (pc10)  0.0%    |                     | C10-SKL    30.0%   12.6 ms 80.8%    9.8 ms


Setting more flags to "Good" does not allow my laptop to resume after closing the lid. And I've to restart the network-manager, but I can live with that.

Date: 2016-10-20 02:30 pm (UTC)
From: (Anonymous)
> These patches never went upstream

Does this mean that using Linux without these patches on Haswell or Broadwell laptop is equally bad as using it on Skylake laptop?

Skylake PC8 or PC10?

Date: 2016-11-05 03:41 pm (UTC)
From: [identity profile] http://openid-provider.appspot.com/e.tomell
Hello,
I own a Dell XPS 15 9550, I hit sometimes PC8, but it's unreliable, I actually thought it never got below PC3 (with F25 beta).
In the second paragraph you wrote:
"The deepest power saving state I can get into is PC3, despite Skylake supporting PC8"
Where does this come from? I've checked the datasheet you linked, on page 66 (paragraph 4.2.5) there is this: "The processor supports C0, C1/C1E, C3, C6, C7, C8, C9 and C10 power states". Is badly worded, it should say PC{0..10}, on page 69 there even is a description of Package C10 State. On page 70 there is a nice table, PC10 can be reached if PSR is enabled, otherwise only PC8 is supported.
I checked then the intel datasheet for H-series mobile processors [1] (like the i7-6700hq I have), the relevant pages are 73-76 (but the table was omitted), but it looks the same. I'm also having an email exchange with another xps 15 9550 linux user, he wrote to me that his system does reach down to PC10, so now I'm trying to get to the bottom of this (I think he's running F24 or 25).
[1] http://www.intel.com/content/www/us/en/processors/core/6th-gen-core-family-mobile-h-processor-lines-datasheet-vol-1.html

Re: Skylake PC8 or PC10?

Date: 2016-12-13 10:42 pm (UTC)
From: (Anonymous)
My Thinkpad P50 can only reach PC3 occasionally on Kernel 4.8.12 with Ubuntu 16.04. Most of the time it's on PC2. I guess the distribution of Linux also plays a role in some detailed configurations?
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Matthew Garrett

About Matthew

Power management, mobile and firmware developer on Linux. Security developer at Google. Ex-biologist. @mjg59 on Twitter. Content here should not be interpreted as the opinion of my employer.

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