# dpkg -l thermald | cat
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-==============-================-============-=========================================
ii thermald 1.9.1-1ubuntu0.2 amd64 Thermal monitoring and
controlling daemon
hardware
Handle 0x0100, DMI type 1, 27 bytes
System Information
Manufacturer: Dell Inc.
Product Name: XPS 13 7390 2-in-1
Version: Not Specified
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https://bugs.launchpad.net/bugs/1874933
Title:
Performance workaround for Dell 7390 2-in-1 Ice Lake
Status in thermald package in Ubuntu:
Fix Released
Status in thermald source package in Focal:
Fix Committed
Bug description:
== SRU justification focal ==
As reported here:
https://www.phoronix.com/forums/forum/linux-graphics-x-org-drivers/intel-linux/1174225-dell-xps-7390-intel-ice-lake-performance-hit-hard-by-a-linux-kernel-regression?view=stream
This primarily impacts "Ubuntu 20.04 LTS (Focal Fossa)." as it switched to
5.4 kernel.
The 5.4 kernel added support for "Processor thermal device", for Ice Lake,
which will expose the power tables (via PPCC).
This system default "max RAPL long term power limit" is 15W. But this
power table is specifying as 9W. So thermald will limit power to 9W.
If dptfxtract is executed, then power limit will be higher than power
up value, but most of the users will use out of the box setup. So this
need a workaround.
This workaround will ignore any power limit less than the power up
power limit.
This is addressed in thermald 2.1 with two commits:
https://github.com/intel/thermal_daemon/commit/f7db434293387c965e8d9141608f855893740e3a
https://github.com/intel/thermal_daemon/commit/c3461690eafb7304bf59a39fb02955a5154b3861
I know 20.04 LTS uses 1.9.1. I can assist in backport if required.
== Fix ==
Two upstream commits to ease backporting:
- eeadf7d2efe Restore to min state on deactivation without
depending on hardware state
- 9a6dc27879a Clean up the code and documentation
Two upstream commits for the fix:
- f7db4342933 Avoid polling power in non PPCC case
- c3461690eaf Ignore invalid PPCC max power limit
== Test case ==
Open two terminals:
-In the first terminal run the following command:
"sudo turbostat --show PkgWatt"
-In the second terminal run some all CPU busy workload, like stress-ng or
mprime
After few seconds turbostat will show that power is capped around 9W.
Install the updated thermald, and repeat.
Now with this fix the power should be capped around 15W.
== Regression Potential ==
This fix involves changing the power limits logic so there is a potential
that this may affect change the throttling behaviour of other systems with
poorly defined PPCC power tables because it now ignores the power limits
less than the power up limits. Users will see their machines run faster
and hence active cooling may crank up (e.g. fans) but I think the speed
improvement outweighs the noise factor.
Note that these changes are already in thermald 2.1 that is now in
Ubuntu Groovy 20.10.
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