apport information
** Attachment added: "PulseList.txt"
https://bugs.launchpad.net/bugs/1763144/+attachment/5111115/+files/PulseList.txt
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https://bugs.launchpad.net/bugs/1763144
Title:
Significantly lower power and thermal limits on ThinkPad T480s (and
probably others) than on Windows
Status in linux package in Ubuntu:
Confirmed
Bug description:
A ThinkPad T480s under windows has a power limit of 44W, both short
and long term, with a thermal maximum of about 93C or so. Under Linux,
the power limits are 44W and 15W (short) or so, and the thermal limit
is 80C, causing a significant performance loss.
Looking at MSR and MCHBAR values, we can see that the values are
correctly at 44W in the MSR, but the MCHBAR is set to a lower value:
$ sudo rdmsr -a 0x610
42816000dd8160
42816000dd8160
42816000dd8160
42816000dd8160
42816000dd8160
42816000dd8160
42816000dd8160
42816000dd8160
$ sudo /home/jak/Downloads/iotools-1.5/iotools mmio_read64 0xfed159a0
0x0042816000dd8078
Setting the MCHBAR to the same value as the MSR register solves the problem.
At some point intel-rapl seems to reduce overall frequency to 600 MHz, though.
The thermal limit is configured in MSR register 0x1a2; rdmsr -f 29:24
-d 0x1a2 returns 20. Setting those bits to 7 increases it, resulting
in performance comparative to Windows.
Most of the analysis is based on the analysis in
https://www.reddit.com/r/thinkpad/comments/870u0a/t480s_linux_throttling_bug/
This applies to all bionic kernels I have tested so far, including
Ubuntu 4.15.0-13.14-generic 4.15.10
---
ApportVersion: 2.20.9-0ubuntu4
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/pcmC2D0p: jak 5881 F...m pulseaudio
/dev/snd/controlC2: jak 5881 F.... pulseaudio
/dev/snd/controlC1: jak 5881 F.... pulseaudio
/dev/snd/controlC0: jak 5881 F.... pulseaudio
CurrentDesktop: GNOME
DistroRelease: Ubuntu 18.04
InstallationDate: Installed on 2018-03-14 (28 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180313)
MachineType: LENOVO 20L8S02D00
Package: linux (not installed)
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: root=/dev/mapper/ubuntu--vg-root ro rootflags=subvol=@
quiet splash vt.handoff=1
ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
RelatedPackageVersions:
linux-restricted-modules-4.15.0-13-generic N/A
linux-backports-modules-4.15.0-13-generic N/A
linux-firmware 1.173
Tags: bionic
Uname: Linux 4.15.0-13-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip kvm lpadmin lxd plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 01/22/2018
dmi.bios.vendor: LENOVO
dmi.bios.version: N22ET31W (1.08 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20L8S02D00
dmi.board.vendor: LENOVO
dmi.board.version: Not Defined
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias:
dmi:bvnLENOVO:bvrN22ET31W(1.08):bd01/22/2018:svnLENOVO:pn20L8S02D00:pvrThinkPadT480s:rvnLENOVO:rn20L8S02D00:rvrNotDefined:cvnLENOVO:ct10:cvrNone:
dmi.product.family: ThinkPad T480s
dmi.product.name: 20L8S02D00
dmi.product.version: ThinkPad T480s
dmi.sys.vendor: LENOVO
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