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Skylake's Linux power management is dreadful you shouldn't buy until it's fixed (mjg59.dreamwidth.org)
334 points by edward on Apr 13, 2016 | hide | past | web | favorite | 154 comments

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.

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).

Isn't there an option in Control Panel "Change what happens when I press the power button"?

The button does what I want. I just want it somewhere that is tactilely (is that a word?) different than the volume buttons. I have the same problem with kindles, I hit the power button instead of the volume buttons. This is one of the things that apple got right.

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.

I have the battery drain during sleep problem.

Argh, I probably have this with an XPS 9350 - I wonder if Dell will patch it.

Interesting. Could you tell which model you have? I have had very few problems in general on my SP4 i7-16GB model. I've had to reset the device maybe once or twice in the last ~4 months.

Does that affect the Surface Book too? I just got an i7 Surface Book.

You should check on the surface forums (either reddit or microsoft forums) with users who have the same configuration as you do.

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.


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

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.

"..it looks like they just dumped hardware on the market without suitable software"

Intel has been doing this too with the NUC. If you go on the Intel forums, you'll find people having serious problems right now with Skylake NUCs [1].

Even the previous generation of NUCs (that were released over a year ago) still have major bugs with Linux. For example, there's a BIOS bug that reboots the machine instead of shutting down. They've known about it for at least 5 months now and it's still not fixed [2]. And it seems likely to affect all versions of Linux, not just some obscure variant.

[1] https://communities.intel.com/docs/DOC-110236 [2] https://communities.intel.com/thread/88822

Yeah, I was writing the same exact though before seeing your comment. Seems plausible. Maybe they didn't had enough cpu for the Iris Pro 15" macbook pro, but there seemed to be no reason why they hadn't updated the macbook/13" macbook pro yet.

If you visit hackintosh sites, the community is trying to make osx work properly on skylake, but there is no clear path to a solution yet either.

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.

Yes, otherwise you end up with this: https://www.youtube.com/watch?v=y39D4529FM4 ;)

(I'm well aware it's not a realistic experiment, but it's a fun demonstration nonetheless.)

That video reminds me of childhood, good old Tom's Hardware :)

Those poor CPUs. The first two no-heatsink temperatures are lower than my 2600k's idle temperatures - what's changed?

The Intel CPUs throttled to an absolute minimum state of power draw in order to keep itself from frying. Those chips also came with an integrated heatsink, like modern chips, that provides just enough heat dissipation to keep the CPU from frying itself before it can throttle down.

That video was made because AMD didn't incorporate such protective features back in that era. That's why their chip absolutely fries itself within moments of removing the heatsink. 100W through an area the size of a Tic-Tac (die area dedicated to cache uses almost no power) is a recipe for catastrophic failure if left unchecked.

My old Q6600 could do this to a degree. Sometimes the fan wouldn't spin up on boot, so there was just passive cooling. i'd try playing a game/doing something and performance would start digging it's way to China.

At which point I'd take the side of my PC off, and manually spin the fan until it got the idea.

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.

This depends on the distribution. Fedora for example has GPU switching using PRIME working fairly well and automatically disabled the dGPU by default.

Wasn't aware of that, though the current performance of nouveau is pretty horrendous. At least for newer cards. It's a bit unfortunate but to essentially have a working card you must have the proprietary drivers installed.

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.

For what it's worth, I have a Dell XPS 15 bought in January 2016, with i7-6700HQ Skylake CPU, and I think it has an NVMe drive (at least the drive ID says so). It's the basic model without a touch screen.

I run Debian-testing (aka Stretch), which ships with linux 4.4 and Wayland. I had weird issues with X11, but I had blamed that on the NVidia/dual-card setup which I did not bother investigating.

Besides that, I've had no issues at all with the laptop. I haven't even run the BIOS update yet. Only annoyance was the lack of select-to-copy in Wayland/Gnome, which apparently is fixed in the new version. :-)

There was a BIOS update that supposedly fixes power management for NVMe drives: http://www.laptopmag.com/articles/dell-xps-13-battery-life-f...

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.

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.

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.

If you can download the actual video file and play it outside the browser, you may be surprised how efficiently it can be played by mpv[1] or maybe vlc.

5 years ago I had a desktop computer that was 5 years old, and it plain couldn't handle std-def hulu video at the time and struggled a bit with youtube, but could play good-bitrate 720p h264 smoothly with mplayer - without hardware acceleration. I'm sure hardware acceleration helps, but it seems to partially make up for the inefficiency of the browser-context rendering.

[1] https://github.com/mpv-player/mpv

Yeah why is that? My Macbook goes nuts like a hair dryer on full when playing a youtube video, where the giant ipad with the same dimension and resolution video is all yawn.

I had this too, on Chrome on my MacbookAir 2012. Then I found this: https://chrome.google.com/webstore/detail/h264ify/aleakchihd...

Google pushes his VP9 format so hard, it serves it to its chrome users on Mac, where it cannot be hardware-accelerated... This is ridiculous, especially when it serves H264 when browsing on Safari!

I installed this app and switched to H264 for all videos, bringing in HW decoding, and since then my autonomy tripled when I go on Youtube binge.

It's a bit of a chicken and egg problem.

Hardware vendors won't support VP9 until it has some usage, and it won't get usage until it has hardware support.

VP9 has some serious space savings, so it's extremely beneficial for Google to use it when possible, and many users will appreciate faster loading video at a higher quality.

Unfortunately they can't know when you'd prefer to have a more efficient decoding experience, so they rank their codecs and use the "highest" one available.

Theoretically, VP9 decoding could be accelerated on Macs, if Apple wanted. The Intel GPUs in Macs support it, the functionality just isn't exposed like the H.264 is.

Safari is served H.264, because it does not support VP9 at all. On the other hand, VP9 streams on youtube are significantly smaller compared to similar quality H.264 streams.

As mentioned in the grandparent, iPads/iPhones/iPods have native hardware H.265 decoding. The iPods have have dedicated MPEG decoding hardware since the early days (one of the advantages of copying/transcoding all music via iTunes), which keeps workload down.

I suppose there isn't much of a market in general purpose computers anymore compared to iOS devices, but is there another reason Apple wouldn't start an arms race in specialized hardware graphics chips based on what they are doing for iOS devices? By that, I mean specialized for low power video playback specifically, rather than high end graphics processing suitable for content creation and games.

> As mentioned in the grandparent, iPads/iPhones/iPods have native hardware H.265 decoding

There's no h265 streaming anywhere at this stage. You meant h264?

Absence of streaming doesn't mean it's not supported in hardware.

There are quite a few rumours of support in hardware from A8 onwards but nothing official from a quick Google. Several sources saying it's used in FaceTime.

I really prefer integrated graphics if they're passable, because graphics card problems are a large part of the discussions in support problems. An even older Mac Pro I had, at age three, began taking a hairdryer on the graphics card to get it to reliably boot.

However, while that older MacBook Pro is just new enough to handle virtual machines pretty well, and the CPU is fine for everything I wouldn't already decide to send to a cluster somewhere, the graphics are a reason to get rid of it. I'd like to get an enormous UHD monitor to put on the wall across the room, plus models get dropped from future OS X versions almost entirely based on graphics capabilities now.

I think this post misses some of the benefits of the new architecture that will eventually be realized.

If you have H.265 content then yes - but no one currently uses H.265 on websites.

I had this issue on older Mac's, but my 2014 Macbook Air (1.4Ghz Core i5 Haswell, HD 5000) has been silent when watching 1080p YouTube and Netflix.

Have you considered using a Xeon since you're looking at a 4690K? You might appreciate this tip:


I need high single thread performance, and at most 4 cores for the occasional 4 thread software. This is why I am going for a "k" processor, and why it is an i5 instead of i7

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

It's the other way around though?

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!

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.

>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.

Can link to / provide additional detail on the Windows 7 issues? How weird that an OS simply doesn't work on a processor!

skylake works fine on OSX, even hackintosh.

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?

Metal layers where electromigration would occur haven't scaled to the same degree as the transistors. I would suspect hot carrier injection (which is coinciedentally worse at higher thermal temperatures) is becoming a greater issue as the transistor channels and gate oxide thickness shrink.


That would be my bet. They probably assumed based on typical workloads, a certain percentage of the time, the part would be asleep. Which is generally a reasonable assumption for non-server parts.

More sleep means less activity, and less heat (which accelerates EM)

The desktop Broadwell CPU was supposedly canceled because they had lifespan problems.[1] Overclocking sites report that Skylake processor life suffers badly when overclocking is attempted. Now Intel is effectively saying their CPU is intermittent-duty only. Intel may be having serious problems with electromigration.

Is this the limit for CPU speed and transistor size?

[1] http://wccftech.com/intel-debating-commercializing-broadwell...

Now Intel is effectively saying their CPU is intermittent-duty only.

That's really disturbing if true. Poor power management has resulted in devices being warmer than they need to be and shorter battery life, but that seems trivial in comparison to the hardware actually being damaged. IMHO I would consider it a flaw if a CPU did not last effectively forever at full load --- older OSs which lacked any sort of power management basically kept the CPU in this state all the time, and there's plenty of old hardware around and working to show that it isn't unrealistic.

It seems they're heavily sacrificing lifespan for performance, which is attractive to (most) users and also builds in some planned obolescence, but it's sad that what was once considered to have indefinite lifetime is now almost a consumable. To use a car analogy, this is like moving from a conservatively designed engine that lasts hundreds of thousands of miles but only produces 100HP to a top-fuel dragster engine that can produce thousands of HP but can't run at full power for even a minute without destroying itself.

Making the CPU consumable is a smart from their PoV since the rapid increase in performance every generation has plateaued.

I still do all my development at home on an i5-2600K and an i5-2430 laptop, neither is noticeably slower than any of the new machines I've used (both have SSD's).

I'll probably run this desktop til it dies as there is no compelling reason to upgrade.

Can you imagine a future where we get so used to producing microprocessors this way for so long that another consideration for long-distance space travel becomes "but will the CPU still work when the rover gets there"?

Presumably Intel is having electromigration problems with their chips because the feature size is so small-- 14nm. Space hardware tends to use rad-hard chips, which use bigger transistors. Curiosity apparently uses the RAD750, which has a 150nm feature size, and can be clocked up to a blistering 200MHz.

And costs a blistering $200K.

The US applies export controls to radiation-hardened ICs, which has resulted in a dearth of rad-hard ICs. Nobody wants to run a silicon on sapphire fab any more.

To me this is more worrying for GPU's at future process nodes. Most modern video games push my i5-4570 to reasonable levels, but my R9 290 uses over 3X the power (and generates 3X the heat). If electromigration is much more prominent due to feature size we could see GPU's dying a lot faster than CPU's.

Intel sells Broadwell Xeons, so if they had an electromigration problem with their 14nm node, they must have fixed it by now. Either that or they're going to recall a ton of server chips.

Server chips are usually equipped with better cooling though, so the problem may not be as acute there. There's also the possibility than Intel is only now finding out the problem with their 14nm process, now that Broadwell has been around for a few years.

Electromigration is more of a metal-layer interconnect problem. With wacky new transistor structures, we are more likely to see transistor problems, like hot-electron effects and other device-level problems.

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.

Or the worst, I've ordered a XPS13 some days ago ;-)

I was thinking of going AMD for my next system. This post solidifies that decision. Hopefully when their next-gen arch is released [1] it won't be as buggy as Intel's -- which seems like a fairly low bar.

[1] https://en.wikipedia.org/wiki/Zen_%28microarchitecture%29

I've just build AMD system for myself based on FX 8320 and so far I love it. I am developer and I am constantly running multiple applications (http server, db, multiple chrome tabs) which are using multiple cores. FX series also supports VT and many other features http://cpuboss.com/cpu/AMD-FX-8320 on top of that usually mobos are supporting 32/64GB RAM even in cheaper boards, and it's enough for casual gaming, not bad for used £90 CPU with CM Hyper 212 EVO cooler

Note that several commenters on phoronix[0] are saying that they are not having any problems (along with the commenter on this thread[1])

[0] - https://www.phoronix.com/forums/forum/phoronix/latest-phoron...

[1] - https://news.ycombinator.com/item?id=11492693

Yes, the behaviour between desktop and mobile parts is very different on current Intel. You'll only see this on mobile - I'm sorry for not having made that clear.

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.

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)

This x1000. Always get the Precision 15" over the 13"...the hardware is just better suited for Linux. The Sputnik team has to take chassis from other Dell products and support them as manufactured...this is why the XPS 13 DE has Broadcom. I have a XPS 13 DE from last year and I wish every day I would have just ponied up and gotten the 15.

But keep in mind that Dell is releasing their drivers into upstream kernels, so if you are on 14.04, you should be using the LTS Enablement stack in order to avail yourself of the latest firmware with stability improvements (this is how I fixed the Broadcom Null pointer bug).


You don't have to use the LTS Enablement Stack if you installed with newer service pack .isos.

The 15" also has Thunderbolt which is a must if you want to have a reasonable docking solution for a Linux laptop.

So thats what LTSE is. Saw it in the compatibility table for the TB15 thunderbolt dock.

Which, I really can't tell if it'll work or not. Really need to plug a 4k monitor into it.

Yeah, LTSE is how you can keep upgrading your kernel while staying on the LTS releases of Ubuntu. Granted you are limited to the kernel versions of the previously released Ubuntu version and there is a slight delay between when a new version is relased and when it becomes available to LTSE, but overall I have found the stability to be good.

From what I found out (if I remember correctly), I have great confidence that Thunderbolt docks should work well with Linux kernel 3.19+. But take this with a grain of salt since I ended up with the 13 DE and therefore only have a mDP and couldn't try a Thunderbolt dock.

Can confirm. Have the Precision 5510. With the 4.4 kernel, it more or less works fine. Last I checked, I was getting ~5hrs on battery. Which is pretty shit-hot for a linux laptop.

One gripe so far: Since I updated the BIOS, the entire thing performs like a Netbook-Hype-era Atom CPU when there's no AC power.

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?

Could you paste the output of sudo lspci -vvv and cat /sys/devices/virtual/dmi/id/bios_version somewhere?

Not OP, but I have dell xps 15 skylake. (i3-6100H)


I am currently running Ubuntu 16.04 4.4.0-8 kernel which works fine. The ubuntu backport of i915 from 4.6 to 4.4 which is present in 4.4.0-9 causes weird video issues. (upstream bug: https://bugs.freedesktop.org/show_bug.cgi?id=94593)

Only the ultra-low-power chips (U and Y series) are susceptible to damage from poor power management.

any source?


lspci -vvv: http://pastebin.com/raw/FUsMqPZz

cat /sys/devices/virtual/dmi/id/bios_version: 1.2.3

Happy to provide any other info as well, I love this machine to bits and would be happy if I could help other people enjoy it too.

Could you re-run the lspci as root? Thanks!

This is probably a slightly different configuration, but I also see support for low Cstates on my Skylake processor (running 4.6.0 rc2)

sudo lspci -vvv : http://pastebin.com/79BfxQC4

Sorry about that! here you go:


also, what kernel version is (uname -a)

Linux eenie 4.4.0-1-amd64 #1 SMP Debian 4.4.6-1 (2016-03-17) x86_64 GNU/Linux

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.

There's no such thing as SP1 from Canonical, sounds like a Dell invention.

They mean they're shipping the 14.04.01 LTS, the point release that comes out three months after the main release. Dell actually ship a custom enabled Ubuntu version - it's one of the LTS releases that's stable with any custom work that was done for them on enablement. Which is why buying from Amazon isn't going to provide the same experience.

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.

Offtopic-ish, but the 2015 model recently had its sound completely demolished by a kernel release in arch. The only fixes are to either downgrade the kernel or recompile it with a flag. Both fixes are annoying as all hell and there doesn't seem to be enough support from arch nor dell to fix this problem!

Camel, meet straw.

Well, it makes sense because Arch's policy is to follow upstream with minimal patches, so they would wait for the new kernel to fix the bug rather than applying a patch themselves. If you don't like this policy, you might want to pick a different distro or use your own kernel.

Nah, I totally get it. It's still incredibly frustrating, especially considering it only broke after spending three hours fixing an issue that pacman itself caused. I'm definitely in the works of finding a new distro. :)

OpenSUSE Tumbleweed has much better testing, and is actually faster than Arch in some cases. I've switched a lot of my machines recently. And you can use OBS which actually builds "AUR" packages for you (you can branch them on OBS if you want to modify them, or you can even download and modify the package locally).

If I didn't run Fedora and CentOS on my servers at work I would probably switch to Tumbleweed on my XPS 13. In reality I shouldn't really need to keep my development environment so close to what I deploy on, but it's nice to be able to quickly test a RPM I'm packaging without needing access to my server at home/work or dealing with a VM or docker.

NixOS or Void linux are rational alternatives to Arch

What kernel version/distro were you running with Linux when you experienced the panics?

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?

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.

Sadly that is usually what happens. Something or other do not work in Linux but work in Windows with OEM drivers installed? Blame Linux even though Windows is getting help from the OEM that Linux lacks...

To be fair, Microsoft seems to be having problems putting the chip into deep sleep as well so clearly Intel is being too secretive this time. Maybe they are trying to cover something up about Skylake? I've heard from friends in OSG that they can't get the power consumption of the chip down to what Intel claims it should be in deep sleep.

Thanks for the heads up. Between that and the discussion elsewhere about designing with the intent of parts being "off" much of the time reminds me that Intel tried to replace TDP with another term that was supposed to take "typical" usage into account. Never mind that they recently abandonded their tick tock development strategy recently. Really starts to look like they have run into something troublesome...

It's an issue with Skylake to the extent that Intel do their own hardware enablement for Linux and just haven't done everything they need to in this case. C8-SKL refers to the C state that an individual core is in - the package C states are listed further to the left in the "Package" column.

I think the package column is also showing C8, although I'm not familiar with the layout. Here's an example of what I currently see:

            Package   |            CPU 0
  Powered On  0.0%    | POLL        0.0%    0.0 ms
  C1E-SKL     1.3%    | C1E-SKL     0.2%    7.1 ms
  C3-SKL      0.0%    | C3-SKL      0.0%    0.2 ms
  RC6pp       0.0%    | C6-SKL      0.0%    0.0 ms
  C7s-SKL     0.0%    | C7s-SKL     0.0%    0.0 ms
  C8-SKL     64.5%    | C8-SKL     99.6%    9.5 ms
                      |            CPU 1
                      | POLL        0.0%    0.0 ms
                      | C1E-SKL     0.0%    0.0 ms
                      | C3-SKL      0.0%    0.0 ms
                      | C6-SKL      0.0%    0.6 ms
                      | C7s-SKL     0.0%    0.0 ms
                      | C8-SKL    100.0%   84.8 ms
                      | ...
What would I see if it were properly using C8?

Hm. Which version of Powertop is this? Your output is corrupt - RC6pp is a GPU power state, the package states should all be "PC". The output I have looks like https://gist.github.com/mjg59/c753a7cb868fbbfa83e6060c4e4d0f...

Oh, are you on a desktop part? The issue is related to the mobile ones. I've updated the post to make that explicit.

Yes, this is a desktop i7-6700. Sorry if that confused things. Yes, the addition to the top of the post is much clearer. Thanks!

Generally someone is more invested in a particular OS than a particular CPU. I am far more likely to buy a different piece of hardware in order to have proper Linux support than to switch to an entirely different os. Whether its the hardware maker or Linux that is at fault is immaterial.

Broadwell for example (Skylake's predecessor) runs Debian Jessie absolutely beautifully on my T450s laptop. Great battery life and integrated graphics performance.

I'd rather it read: "Skylake's Linux power management is dreadful you should buy now and help fix it". But, as others have commented, this appears to be Intel not doing their job as hardware manufacturer. It's sad that we're still having these type of issues after years of cross-os growth on Intel/AMD architecture (Windows NT, Linux, OS X, *BSD etc).

The title of the post is actually "Skylake's power management under Linux is dreadful and you shouldn't buy one until it's fixed".

I had to rewrite it to get it under 80 characters.

>"Linux's power management on Skylake is dreadful and you shouldn't install it until it's fixed?"

Because Linux is sometimes the only option. No other OS has the same options as far as containerization.

FreeBSD has Jails and Solaris has Zones, you know, and have done since the early 2000s.

You might want to watch some of Bryan Crantrill's talks on FreeBSD Jails, Solaris Zones, and his criticisms of Docker and Linux containers in general when compared to them.

I generally think while they aren't as isolated as Jails or Zones, LXC containers are 'fine' for isolation. My big beef is with Docker and the lack of any decent management tooling, whereas I can just treat a LXC container like any other 'real' system and use puppet as such.

Still, Solaris Zones are freaking awesome, with them having a Linux personality now I really need to try to find some time to mess with SmartOS more.

Ok so this is completely wrong. Both FreeBSD and the entire Family of OpenSolaris derivatives offer:

- Superior "container" support to Linux (more secure, better tested, better designed, not a hacky bolted on thing like Cgroups.)

- Their source code, they are Open Source

Or did you actually just mean to say "Only Linux has Docker"?

Actually, SmartOS (Solaris) has some magic Docker fakery that makes containers run in LX-branded zones. I'm a maintainer of runC (the low-level executor of Docker) and I just merged some code the other day that is working on running runC natively on Solaris. I'm quite excited about that. As for FreeBSD, there was some work in Docker some time ago on getting Docker to work on FreeBSD. I don't think all of the code is there though.

Are you saying that Skylake doesn't have these problems when running FreeBSD or OpenSolaris?

FreeBSD even has docker, portname sysutils/docker-freebsd

1. Reference to this superior "container" technology? (geniunly interested to read about it).

2. Source access to the OS don't mean squat unless you're you can grok OS code. Also how is BSD open source different to Linux's?

They're likely referring to Solaris Zones and FreeBSD Jails.

Re 1. I think he's referring to "FreeBSD jails".

> - Their source code, they are Open Source

So does Linux?

People who run Linux for serving production traffic generally disable power management, and for good reason. So it's a non-issue in that context.

If you're doing Docker 'properly', your developers will be using it on their machines, so there is ample context for containers on a laptop.

In most cases they're running Docker in a VM on a Windows or Mac OS laptop, so the host's power management will be used.

Most of my coworkers do this, but their VMs are insanely slow and my native Linux is fast, so I can work more productively by running Linux.

What containerization options does Linux have running on bare metal, that a Linux VM running under OS X on a properly power-managed Macbook doesn't ?

Properly power-manager Macbook on OSX has its own share of hardware/driver-related problems (like the unreliable wifi), so let's not slide into irrelevant arguing.

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.

This reminds me of something.. Oh, right. Baytrail support. that's still lacking as well, and that's also a C-state issue.


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

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 ?

Here is lspci, powertop frequency and bios version for my 9550 Dell. Not getting the package deeper than PC6 either.


Btw. I noticed that a new bios was posted yesterday. Unfortunately it is not yet available in whatever place fwupdmgr is looking at. But at least bios updates now work from Linux on this laptop.

Ah - is this a quad-core CPU? Interestingly there does seem to be a pattern building up here, which is that it's more SKU specific than I previously thought - it now looks like it's limited to the S and U parts, which are paired with the Sunrise Point-LP PCH. CPUs that are using Sunrise Point-H appear to work more as expected.

Thanks, I'll try to replicate your PCI configuration and see if I can trigger any behavioural changes.

I think I'm seeing a similar usage on my 9550 here https://gist.github.com/shadeslayer/4184b49505d817a9a60d5b0a...

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.

The Intel graphics driver (i915) has an issue in Linux 4.4.0 which causes occasional black frames. Other than that it's running perfectly for me.

No issues. Had one when they pushed an update for nvidia but other than that it's smooth

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.

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.

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.

As mentioned by the article, this applies to mobile version of the cpu only (so laptops, etc.) It does not affect desktop versions.

It's not in the headline, but this is about mobile SKUs, not desktop.

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.

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.

Hmm... 8 watts sounds extremely high to me. My Broadwell laptop uses less than 3 watts when idle, and most of that is the display. Even my old Ivy Bridge MacBook Air from 2012 idles at 5W. Is there some peripheral responsible for the higher idle on your system? Maybe a hard disk or dedicated GPU? I'm curious about what's causing the difference.

CPU/GPU power usage: (≈1W) http://geoff.greer.fm/photos/screenshots/Screen%20Shot%20201...

Total power usage: (2.9W) http://geoff.greer.fm/photos/screenshots/Screen%20Shot%20201...

You were right! I barely use it on battery so I never investigated.

I installed tlp and system went down to 5.5W idle with normal programs open. On fresh boot as low as 4.9W.

Turning the screen off shaves 2.5W, and disabling the wireless card saves ~1W.

I suspect the SSD + HDD are making part of the difference.

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.

Intel's documentation says that long-term reliability of the hardware isn't assured in this configuration, so yes, it's broken.

This is so frustrating, especially when you buy a $3000+ laptop (which is a lot for a laptop in Croatia) only to have to find this shit out on your own, because it's a very specific thing you need to Google.

And it is even more frustrating that people complain it's Linux's fault because it "works fine on Windows" (no it doesn't actually[1]), when hardware vendors suck up to Microsoft and have a "oh yeah whatever" attitude towards linux users most of the time.

And then people ask themselves why Linux runs better on "old hardware" because it takes years sometimes for all the shit to be ironed out. Ugh! So annoying.

Sorry for useless rant.

Edit: Hardware vendor shaming needs to be a thing. Most of the time this types of things go "quietly" and this is why nobody at the "management" level cares.

[1]: https://news.ycombinator.com/item?id=11153940

Intel actually provides a lot of code to the Linux kernel. At least as of a year ago they were the top contributor to it: http://www.linuxfoundation.org/news-media/announcements/2015...

Yes, and that is really great, but it would be even greater if they adequately supported their newer & "consumer-level" (for a lack of better expression) hardware as well.

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