top | item 11492070

Skylake's Linux power management is dreadful you shouldn't buy until it's fixed

334 points| edward | 10 years ago |mjg59.dreamwidth.org

154 comments

order
[+] dman|10 years ago|reply
For what its worth Microsoft has struggled with power management on mobile skylake as well - https://www.thurrott.com/mobile/microsoft-surface/62772/micr... . There have been multiple firmware upgrades but if you look at /r/surface on reddit multiple people (myself including) still have issues with power management and sleep on the skylake surface pro 4's.
[+] StillBored|10 years ago|reply
It is nice when your devices appears to always be on. But lets be real, my windows tablet isn't a phone.

So, I disabled InstantGo/Conected Standby on my dell tablet, and the battery now runs for days. I charge it once a week or so, unless I start playing games on it (in which case the battery only lasts for something like ~3/4 hours). That device gets pretty heavy use for book reading/ netflix/ web surfing.

The downside is that the power button is stupidly placed next to the volume buttons. So I frequently hit it instead of the volume button and that results in a ~5-10 second hibernate/resume sequence. I've been considering how hard it would be to physically cut the lead to it and the useless "window button" and PtP solder the windows button as the power button. (I haven't found any software solutions for reversing them).

[+] rorosaurus|10 years ago|reply
Problems with wake? I see those sometimes. I haven't seen the rapid battery drain in sleep people talk about (yet). Still, I'm nearly convinced to return my SP4 device due to frustration from these issues.
[+] lmm|10 years ago|reply
Does that affect the Surface Book too? I just got an i7 Surface Book.
[+] hacknat|10 years ago|reply
I can personally confirm this. I bought a brand new Dell XPS 15 with Skylake (i7) in December. I installed Linux on it (kernel 4.3), and it has been a power management nightmare from day 1. I've only ever gotten 2 hours from the battery. I just sent it in because it powercycles at random now, never making it past the Dell splash screen anymore. When I run the hardware diagnostics, sans hard-drive, it dies in the middle of one of the processor tests.

Other people have been pointing out that Windows is struggling with Skylake as well, and I've heard the same.

Skylake was touted by Intel as being one of their proudest achievements in power management to date. My guess is that their changes were so drastic that the software didn't keep up.

Edit:

I do have an NVMe hard drive, which does seem to cause some issues, for reasons passing understanding.

[+] UVB-76|10 years ago|reply
Perhaps this explains why Apple have been so slow to get their Skylake MacBooks to market.

I was disappointed other OEMs had beaten them to it, but it looks like they just dumped hardware on the market without suitable software. Apple obviously take responsibility for both.

[+] userbinator|10 years ago|reply
My guess is that their changes were so drastic that the software didn't keep up.

It's one thing to be running hot all the time, it's an entirely different thing to actually cause damage because of that.

This reminds me of some laptops a few years ago which would overheat just sitting in the BIOS setup screen for too long, because the fans were entirely software-controlled and that hadn't been loaded yet.

I don't think power management should ever be left to software entirely if it can result in situations like this - software can make the CPU go into a lower power state, but the CPU should know when it's too hot and throttle itself without any intervention from software.

[+] 0X1A|10 years ago|reply
I have this exact machine with an i7 and do not get anywhere as low as 2 hours. Do you have bumblebee installed? It sounds like you might have the dedicated graphics runnign at all times, which is the case if you don't have e bumblebee + bbswitch installed.
[+] kibwen|10 years ago|reply
Offtopic: other than power management, how has your experience been with Linux on an XPS 15? I've been holding off with mine until the next Ubuntu release, later this month.
[+] DanGarcia595|10 years ago|reply
This is weird because I was reading a thread on Ubuntu forums about 4.3 problems and I've just stayed on 4.2 with 15.10 with no power management issues. Power consumption is criminal though getting 1.8 hours average at full charge and low brightness.
[+] speeder|10 years ago|reply
I am planning in buying a 4690K

LOTS of people keep nagging me that I should go for a Skylake instead, just because it is "newer" and "better because it is new"

I really don't understand that logic.

Beside the thing pointed in the article, Skylake has other problems:

Win7 don't work properly in it (and Win7 is the last Windows to emulate old DirectX versions correctly on Windows itself).

Skylake wasn't design to support analog video at all, something that is still common in third world countries, specially as people keep using old monitors that never break, and are frequently superior to almost all reasonably priced new monitors.

Skylake doesn't support OSX (and there are people with reasons to want that).

Skylake uses DDR4, that in third world might not be even available for sale, or might have some insane prices (2, 3 times the DDR3 price).

Skylake has a couple bugs, and more might pop up in the future.

except in US and maybe some EU countries, the price to build a Skylake system is higher than the speed benefit it gives compared to Haswell (usually at most 10%, frequently less...).

EDIT: I would also like to point out that Devil Canyons has been reported to work with DDR3 up to 2666 with no issue, some mobos allow Devil Canyons to go up to DDR3 2800 without erroring or being unstable.

The thing is, those DDR3 can ALSO reach much lower latency than similar bandwidth DDR4, the few DDR3 vs DDR4 benchmarks done so far, show that usually there is no difference, and when there IS a difference, is usually DDR3 winning.

[+] rz2k|10 years ago|reply
Will the inclusion of HEVC/H.265 decoding in the integrated graphics be beneficial?

On an older MacBook Pro I have with Intel HD Graphics 3000, the fans go beserk on video that my iPad handles with passive cooling without even becoming warm.

I can imagine the codecs used on everything you encounter on regular sites will quickly begin to expect optimizations built into Skylake.

[+] zvrba|10 years ago|reply
> Skylake doesn't support OSX (and there are people with reasons to want that).

It's the other way around though?

[+] emp_zealoth|10 years ago|reply
ive recently bought an 4690 (and 16GB low latency DDR3 ram) - it is a goddamn beast, especially considering it was an upgrade from C2D E8400 and 4GB of crappy old DDR2

My advice though is: look at PCI passthrough, for example 4670 has all the tech required, 4670K doesn't, 4690K does again

As soon as vm's get good enough for a semi-newb like me to work it,im moving to Linux host (running on i7's GPu) with vm Windows (with its own pci-passthrough discrete GPU)

Caaaaant wait!

[+] TD-Linux|10 years ago|reply
Even in the US, it doesn't really make sense. Especially with the Xeon parts. You do get a much nicer integrated GPU though, if you use that.
[+] andersen1488|10 years ago|reply
>except in US and maybe some EU countries, the price to build a Skylake system is higher than the speed benefit it gives compared to Haswell (usually at most 10%, frequently less...).

Honestly, even in the US I don't think it's worth it. I thought about upgrading from my Haswell i5 and the benchmarks are actually lower on a single core. Unless you truly need the Hyperthreading there's no point in upgrading.

[+] j_s|10 years ago|reply
Can link to / provide additional detail on the Windows 7 issues? How weird that an OS simply doesn't work on a processor!
[+] Gelob|10 years ago|reply
skylake works fine on OSX, even hackintosh.
[+] Animats|10 years ago|reply
Intel: "Long term reliability cannot be assured unless all the Low-Power Idle States are enabled."

Does that mean if you run the CPU too much, it will die quickly? Is there some low limit on time at full power? Electromigration problems, perhaps?

[+] openfuture|10 years ago|reply
This is literally the best timing ever. I was going to place the order for my XPS 13 yesterday but ran into some banking trouble. Then on my way to the bank today I was browsing HackerNews on my phone and now I'm conflicted if I should go through with the purchase or try to find the older model.

Does anyone have a reasonable guesstimate as to how likely it is that this gets fixed, because it sounds to me (from this thread) that there is a flaw in the design of the chip and this won't be fixed so easily.

[+] _Codemonkeyism|10 years ago|reply
Or the worst, I've ordered a XPS13 some days ago ;-)
[+] TYPE_FASTER|10 years ago|reply
A few semi-relevant notes: * We've bought multiple Dell XPS 13 laptops with Windows off Amazon because the same spec there was roughly $400-500 cheaper than buying the XPS Developer Edition from the Dell website. * We tried running Linux on a Dell non-XPS Skylake Core i7 laptop and it was having many kernel panics. A quick Googling revealed people with a Skylake chipset having a similar issue. * I noticed just a couple days ago that Dell has updated their XPS Developer Edition laptop to Skylake. One difference I see on the site is it ships with Ubuntu 14.04 SP1. I haven't read much about SP1, other than it looks like it's about a year old.

So yeah, I'm still buying XPS laptops with 5th gen chipsets because we've had issues with Skylake.

[+] davidbanham|10 years ago|reply
Keep in that the XPS units often have Broadcom wifi chipsets while the developer edition units have Intel. Much better Linux driver support for the Intel cards. The Precision 15" now comes in the same chassis as the XPS and has the Intel chipset (and other goodies)
[+] chias|10 years ago|reply
A couple months ago I bought a Dell XPS 13 (signature edition) off of Amazon because it was a few hundred dollars cheaper than buying it from Dell, and installed Linux over it.

It's a Skylake machine, and it's been working great. I'm using Debian Testing with the kernel pulled from Sid (necessary to get the wifi working).

Powertop output is:

    Package             |             Core    |            CPU 0       CPU 2
                        |                     | C0 active   6.7%        3.9%
                        |                     | POLL        0.1%    0.2 ms  0.0%    0.0 ms
                        |                     | C1E-SKL     5.5%    0.2 ms  1.3%    0.2 ms
    C2 (pc2)    9.7%    |                     |
    C3 (pc3)    2.2%    | C3 (cc3)    2.5%    | C3-SKL      3.2%    0.3 ms  0.4%    0.2 ms
    C6 (pc6)    4.1%    | C6 (cc6)    7.0%    | C6-SKL      8.0%    0.3 ms  8.4%    0.7 ms
    C7 (pc7)    0.0%    | C7 (cc7)   28.7%    | C7s-SKL     0.0%    0.1 ms  0.0%    0.7 ms
    C8 (pc8)   12.1%    |                     | C8-SKL     29.4%    1.9 ms 60.5%    2.3 ms
    C9 (pc9)    0.0%    |                     | C9-SKL      0.0%    0.0 ms  0.0%    1.3 ms
    C10 (pc10)  0.0%    |                     | C10-SKL     4.3%    3.6 ms 14.6%    4.1 ms

                        |             Core    |            CPU 1       CPU 3
                        |                     | C0 active   5.2%        4.4%
                        |                     | POLL        0.0%    0.0 ms  0.0%    0.2 ms
                        |                     | C1E-SKL     1.5%    0.2 ms  1.5%    0.3 ms
                        |                     |
                        | C3 (cc3)    0.6%    | C3-SKL      0.7%    0.2 ms  0.7%    0.2 ms
                        | C6 (cc6)   14.7%    | C6-SKL     10.8%    0.7 ms 13.8%    0.8 ms
                        | C7 (cc7)   52.0%    | C7s-SKL     0.1%    1.1 ms  0.0%    0.4 ms
                        |                     | C8-SKL     59.6%    2.1 ms 59.8%    1.8 ms
                        |                     | C9-SKL      0.0%    0.0 ms  0.0%    0.0 ms
                        |                     | C10-SKL     9.7%    4.4 ms  8.4%    3.5 ms
              
                        |             GPU     |
                        |                     |
                        | Powered On 13.2%    |
                        | RC6        86.8%    |
                        | RC6p        0.0%    |
                        | RC6pp       0.0%    |
                        |                     |
                        |                     |
                        |                     |
                        |                     |
                        |                     |

As far as I can see, this seems to imply C8 is working fine?
[+] tbrock|10 years ago|reply
That seems to make sense to me. Running a 2 year old OS (even with 1 year old service pack) on bleeding edge laptop and you don't expect to have problems? Doesn't compute. This is not an LTS situation, live a little.

Why not try Ubuntu 15.10 or 16.04 beta? At the very least run something released in the last 6 months if you have any reasonable expecatation of things working.

Seems like all the Arch folks have this working also.

[+] zurn|10 years ago|reply
There's no such thing as SP1 from Canonical, sounds like a Dell invention.
[+] IMcD23|10 years ago|reply
I've been running Arch on a 2016 model XPS 13 Signature Edition. Everything worked out of the box crash-free. This includes Broadcom WiFi, Skylake CPU, media keys, multitouch tracked, and touchscreen.
[+] dmix|10 years ago|reply
What kernel version/distro were you running with Linux when you experienced the panics?
[+] nkurz|10 years ago|reply
Skylake's Linux power management is dreadful you shouldn't buy until it's fixed

Why is this phrased as being an issue with Skylake, rather than an issue with Linux? That is, why not "Linux's power management on Skylake is dreadful and you shouldn't install it until it's fixed?"

Also, as someone who is running a custom compiled Linux 4.4 on Skylake, what's the best way to check what idle state is being used? Idle stats with 'powertop' shows the majority of idle time being spent in C8-SKL. Is this the same as the PC8 he's talking about?

[+] izacus|10 years ago|reply
It's phrased like that because it doesn't work on Linux and Intel refuses to document what has to be done in the kernel to make it work. As such it's hard to blame Linux kernel developers for not knowing how to magically poke the complex SoC into low power submission without Intel's cooperation.
[+] lllllll|10 years ago|reply
I got my Asus UX303UA(which won over the dell xps13 option) - i7-u6500 last week. I installed Linux Mint(MATE edition, though I use mainly i3wm). After upgrading to kernel 4.5 I get 8-9h of battery with normal use ( Vim, firefox several tabs, rails/node/redis/postgres server running...), even longer if I'm on-off the computer. I'm really happy with it so far.

Besides, I could add +4GB RAM and replace sata HDD with SSD.

[+] xcasex|10 years ago|reply
This reminds me of something.. Oh, right. Baytrail support. that's still lacking as well, and that's also a C-state issue.
[+] ciokan|10 years ago|reply
https://gist.github.com/ciokan/1bb8a5a23e00d1f4344b04d88debc...

Good or bad? Have no idea what C8 should say that's why i'm asking. Dell XPS 9550 ubuntu 16.04

[+] mjg59|10 years ago|reply
Well, that's better than most people are seeing - getting deeper than PC6 may involve some graphical things. So the question now is why you have such different results to me. Can you paste the output of sudo lspci -vvv somewhere, along with cat /sys/devices/virtual/dmi/id/bios_version ?
[+] db1|10 years ago|reply
Is Ubuntu 16.04 running well for you? I'm also on Dell XPS 9550, but I'm running 15.10. Had some serious issues with the initial install, wondering if I should risk the hassle of upgrading.
[+] blinkingled|10 years ago|reply
I guess with all the pressures and cost cuts in QA you'd be better off sticking to Haswell Gen machine for next few years. Which are perfectly fine by the way - Haswell Xeons for your workstation and anything around the i7-4xxx for your laptop will do you fairly well for next 3 years or whatever it takes for Intel to put out a power efficient, stable and well supported part.
[+] MrQuincle|10 years ago|reply
Seems a bit exaggerated. I now have a Yoga 900 running 4.4.0-18-generic. It's fine to work through the entire day (6 hours).

The only thing that's still causing hiccups is the combination of Wifi and Bluetooth on the same chip which doesn't play nice if I for example stream spotify to my bluetooth speakers. However, that has nothing to do with Skylake.

[+] jonotime|10 years ago|reply
Interesting since I continue to be impressed by my skylake's low power consumption. I built a desktop (arch linux kernel 4.2 - 4.4) a few months back and my killawatt generally show 25-35 watts. Thats way below my old desktop. Its also plenty cool.
[+] viraptor|10 years ago|reply
As mentioned by the article, this applies to mobile version of the cpu only (so laptops, etc.) It does not affect desktop versions.
[+] madgar|10 years ago|reply
It's not in the headline, but this is about mobile SKUs, not desktop.
[+] ikeboy|10 years ago|reply
I had an HP skylake laptop that overheated last month, then refused to boot, running ubuntu. Had constant issues when resuming from suspend, would sometimes refuse to start, or would lose wifi.

Now wondering if it's connected.

[+] bb85|10 years ago|reply
Anecdotal, but I've been running Ubuntu 15.10 for a few months on a Dell XPS 15 (9550), and with kernel 4.4 everything works flawlessly.

When idling, power consumption is 8W, and powertop shows 30% C8 and 70% C10.

[+] suprjami|10 years ago|reply
OK, it's broken and doesn't work. I'm getting over 10 hours battery on a Skylake laptop, but it's broken and doesn't work.