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#1 2019-12-12 23:06:28

chopperdave
Member
Registered: 2019-12-12
Posts: 7

i915 gpu is powered on 100% of time

### Solution at the top ###

Installed the lts kernel from 6 months ago, and now GPU is spending 99-100% of the time in rc6. Power consumption is back down around 3W with wifi on and brightness at a comfortable level.

Using an older kernel solves the power consumption issue, but leaves the machine vulnerable to https://nvd.nist.gov/vuln/detail/CVE-2019-0155 [Thanks Sabroad!]

[SOLVED] tag removed per liewkj's request.

#####################


I'm on an XPS 13 9350 with Arch fully up to date.

In powertop:

|             GPU     |
|                     |
| Powered On100.0%    |
| RC6         0.0%    |
| RC6p        0.0%    |
| RC6pp       0.0%    |

also:

cat /sys/class/drm/card0/power/rc6_enable 
1

When I

sudo systemctl stop lxdm

then GPU goes to RC6 100% of the time, but as soon as lxdm starts again it is back to "Powered On" 100%.

I used to be able to get power consumption under 3W when reading plain web pages, but now it never gets below 6W. This changed in the last couple of weeks. Anyone have suggestions for how to start troubleshooting this?

Last edited by chopperdave (2019-12-19 13:38:37)

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#2 2019-12-12 23:38:38

loqs
Member
Registered: 2014-03-06
Posts: 15,112

Re: i915 gpu is powered on 100% of time

Check /var/log/pacman.log for what packages were updated in that time period.  I would pay particular attention to kernel updates.

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#3 2019-12-12 23:49:42

chopperdave
Member
Registered: 2019-12-12
Posts: 7

Re: i915 gpu is powered on 100% of time

I'd been lagging on updates, so I have many lines and pacman.log for this time period, and there are hundreds that I don't know what they are. Also tried switching to the linux-lts kernel, but that didn't seem to make any difference.

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#4 2019-12-13 11:22:43

sabroad
Member
Registered: 2015-05-24
Posts: 224

Re: i915 gpu is powered on 100% of time

Could you please try with i915.enable_guc=0 and let us know if behaviour is different?


--
saint_abroad

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#5 2019-12-13 16:55:28

chopperdave
Member
Registered: 2019-12-12
Posts: 7

Re: i915 gpu is powered on 100% of time

Thanks for the tip, sabroad!

Still seems the same with that option.

I'm still interested in learning how to troubleshoot this if you have any suggestions, but I'll just re-install arch today to get back to normal.

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#6 2019-12-16 02:13:53

chopperdave
Member
Registered: 2019-12-12
Posts: 7

Re: i915 gpu is powered on 100% of time

Reinstalled Arch and LXDE, Firefox and Thunderbird, and the problem is back. I'd very much appreciate any tips on how to investigate this!

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#7 2019-12-16 04:03:25

dglt
Member
Registered: 2019-08-14
Posts: 82

Re: i915 gpu is powered on 100% of time

chopperdave wrote:

Reinstalled Arch and LXDE, Firefox and Thunderbird, and the problem is back. I'd very much appreciate any tips on how to investigate this!

the thread the marked "[SOLVED]", how was it solved?

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#8 2019-12-16 04:04:59

chopperdave
Member
Registered: 2019-12-12
Posts: 7

Re: i915 gpu is powered on 100% of time

I've edited the first post to show the solution.

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#9 2019-12-16 10:31:50

sabroad
Member
Registered: 2015-05-24
Posts: 224

Re: i915 gpu is powered on 100% of time

I know this is [SOLVED] but can you check 5.3.11 for the issue with no RC6 please and report back?
I'd be curious to know if this is resolved by soft-RC6 (perhaps going into 5.6).


--
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#10 2019-12-18 18:12:53

chopperdave
Member
Registered: 2019-12-12
Posts: 7

Re: i915 gpu is powered on 100% of time

No RC6 in 5.3.11, but going back to 5.3.1 brings RC6 back. I'll narrow it down to the exact version as time allows.

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#11 2019-12-18 18:55:29

liewkj
Member
Registered: 2019-07-08
Posts: 204

Re: i915 gpu is powered on 100% of time

chopperdave wrote:

I've edited the first post to show the solution.

Personally, I wouldn't take such solution of locking down the kernel as far as 6-month back with LTS version. People who would accept such solution would never want to have Arch. They will be more comfortable with Ubuntu LTS or Debian. I think you should also cross check with intel_gpu_top to see if powertop is actually reporting the stats correctly. My Core m3 6Y30 has no issue with RC6 with the latest upstream kernel, but again that was a matured generation of Intel Graphics.

@chopperdave you're right. I was mistaken by looking at Core i3-4010u Haswell graphics, and that wasn't impacted by the CVE. The Core m3 Skylake GT2 graphics is indeed never idle at RC6 and powered 100% of time with kernel 5.4.5-arch1-1. However, I am OK to live with it to have upstream kernel anyway.

Last edited by liewkj (2019-12-19 23:10:12)

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#12 2019-12-19 11:54:05

sabroad
Member
Registered: 2015-05-24
Posts: 224

Re: i915 gpu is powered on 100% of time

liewkj wrote:

such solution would never want to have Arch. They will be more comfortable with Ubuntu LTS or Debian.

The regression was caused by security fix for CVE-2019-0155 backported to all supported kernels. This doesn't solely affect Arch.


--
saint_abroad

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#13 2019-12-19 13:43:00

chopperdave
Member
Registered: 2019-12-12
Posts: 7

Re: i915 gpu is powered on 100% of time

Thanks saint! The details of the vulnerability are beyond my level, do you know if there is a chance that a future security fix for this issue will avoid causing excessive power consumption?

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#14 2019-12-19 23:37:27

liewkj
Member
Registered: 2019-07-08
Posts: 204

Re: i915 gpu is powered on 100% of time

chopperdave wrote:

do you know if there is a chance that a future security fix for this issue will avoid causing excessive power consumption?

I believe such solution would have to come from Intel. I am not sure if they already knew that the mitigation would de-feature RC6 support for iGPU. Most of the CVE mitigation tend to keep quiet about performance/power implication. Someone can file a kernel bug to highlight the issue. Since the CVE is Important not Critical, perhaps a choice can be given to prefer power over security. It depends on the discretion of the kernel folks. Or maybe not at all, since we are now in the computing era that security vulnerabilities freak out everyone.

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#15 2019-12-20 00:50:32

liewkj
Member
Registered: 2019-07-08
Posts: 204

Re: i915 gpu is powered on 100% of time

Look like they did de-feature RC6 and runtime PM with the following commit:
https://git.kernel.org/pub/scm/linux/ke … 1adf5b4438

It does not seem to be associated with any CVEs (or purposely not to mention anything), but an RC6 context corruption. Apparently, the root cause of context corruption was unknown (or refuse to disclose any further) so big hammer of disabling RC6 and runtime PM was put in-place when RC6 context corruption was detected.

However, it seems quite simple to revert the commit if anyone wants to give that a shot. No details about the consequences of RC6 context corruption, the hardware seems to be able to recover per the commit message. Do it at your own risk.

Last edited by liewkj (2019-12-20 20:43:06)

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#16 2019-12-20 12:18:54

sabroad
Member
Registered: 2015-05-24
Posts: 224

Re: i915 gpu is powered on 100% of time

liewkj wrote:

[...]7e34f4e4aad3fd34c02b294a3cf2321adf5b4438 [...] It does not seem to be associated with any CVEs

Sorry, wrong CVE (off by 1):
The regression was caused by security fix for CVE-2019-0154 backported to all supported kernels. This doesn't solely affect Arch.
> Introduced by 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Fixed by 7e34f4e4aad3fd34c02b294a3cf2321adf5b4438


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saint_abroad

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#17 2019-12-20 12:52:24

sabroad
Member
Registered: 2015-05-24
Posts: 224

Re: i915 gpu is powered on 100% of time

chopperdave wrote:

Do you know if there is a chance that a future security fix for this issue will avoid causing excessive power consumption?

Looks like this will be fixed by the soft-rc6 patchset going into linux-5.5.


--
saint_abroad

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#18 2019-12-20 12:59:14

sabroad
Member
Registered: 2015-05-24
Posts: 224

Re: i915 gpu is powered on 100% of time

liewkj wrote:

However, it seems quite simple to revert the commit if anyone wants to give that a shot.

Or can just run linux-5.3.10 until 5.5 is out.

Last edited by sabroad (2019-12-20 13:01:23)


--
saint_abroad

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#19 2020-01-03 09:56:13

kikislater
Member
From: Mauritius
Registered: 2016-01-16
Posts: 32

Re: i915 gpu is powered on 100% of time

So it was solved by downgrading to 4.19 lts ?
Was RC6 problem solved now in 5.5 ? Difficult to follow this problem ...

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#20 2020-01-03 11:10:15

sabroad
Member
Registered: 2015-05-24
Posts: 224

Re: i915 gpu is powered on 100% of time

kikislater wrote:

So it was solved by downgrading to 4.19 lts ?

No, the security fix was backported to LTS kernels.

Need linux kernel <=5.3.10 or <=4.19.83 to use RC6 fully.

kikislater wrote:

Was RC6 problem solved now in 5.5 ? Difficult to follow this problem ...

Yes, it will be resolved in linux kernel >=5.5 but not yet released.


--
saint_abroad

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#21 2020-01-03 11:15:53

kikislater
Member
From: Mauritius
Registered: 2016-01-16
Posts: 32

Re: i915 gpu is powered on 100% of time

sabroad wrote:
kikislater wrote:

So it was solved by downgrading to 4.19 lts ?

No, the security fix was backported to LTS kernels.

Need linux kernel <=5.3.10 or <=4.19.83 to use RC6 fully.

kikislater wrote:

Was RC6 problem solved now in 5.5 ? Difficult to follow this problem ...

Yes, it will be resolved in linux kernel >=5.5 but not yet released.

nice it's clear now !

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#22 2020-01-03 13:33:08

kikislater
Member
From: Mauritius
Registered: 2016-01-16
Posts: 32

Re: i915 gpu is powered on 100% of time

Well, it's pretty impresive !
I revert back to 4.19.81 and power is now around 1.2-1.6W in battery mode on T480S. Thank you, hope patch will be coming soon ...

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#23 2020-02-09 15:17:19

kikislater
Member
From: Mauritius
Registered: 2016-01-16
Posts: 32

Re: i915 gpu is powered on 100% of time

sabroad wrote:

Yes, it will be resolved in linux kernel >=5.5 but not yet released.

Now 5.5.2 is available but no luck ... RC6 still not available and my igpu consume power whereas on 4.19.81 it's 0W.
Any luck ?

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#24 2020-02-10 19:14:55

kikislater
Member
From: Mauritius
Registered: 2016-01-16
Posts: 32

Re: i915 gpu is powered on 100% of time

Solved here : https://gitlab.freedesktop.org/drm/inte … ote_407010

need to adjust minimal iGPU frequency in TLP

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#25 2020-04-08 00:54:44

miomio
Member
Registered: 2016-01-17
Posts: 159

Re: i915 gpu is powered on 100% of time

enable_rc6 was dropped because of something relating to Kaby Lake CPU's? Sorry, far too technical for me. I just wonder if that's the case perhaps applying the patch to revert the change will be OK for me using a non-Kaby Lake CPU. SoftRC6 - how does that work - automatically?

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