Thermal Offset

[cyring]

Starting with commit 9eaf4c5 of develop branch, one can select a temperature offset.

This is architectural, you have to refer to your processor datasheet.

The CoreFreq driver can accept or reject a request if the offset is not within the specified bounds or if there is no implementation (so far Intel only).

Preview: Tiger Lake/U

• Adding 5 degrees to the offset
• You will observe the resulted Core's temperature
  
• Offset is now 15 C
• Decreasing 9 degrees
  
• Offset is now 6 C
  
• Attempting an increase of +20 C
  
• Request rejected: the computed offset must remain within [0, +15]
  

[BugReporterZ]

On my i7-12700K any offset equal or lower than 0 is causing an "Invalid argument" error, while higher values do not seem to work at all.

Note that otherwise on my motherboard it is possible to set in BIOS any TjMax value in the 65-115 °C range; currently I have it at 85 °C. I tried configuring it from CoreFreq also after setting it from BIOS to the default value of 100 °C, but with the same results.

[BugReporterZ]

I set the maximum value in BIOS (115 °C) and this is the result. The relevant bits changed to 73 (hex) -> 115 °C (dec):

# sudo rdmsr -ax 0x1A2
CPU 0: 80731400
CPU 1: 80731400
CPU 2: 80731400
CPU 3: 80731400
CPU 4: 80731400
CPU 5: 80731400
CPU 6: 80731400
CPU 7: 80731400
CPU 8: 80731400
CPU 9: 80731400
CPU 10: 80731400
CPU 11: 80731400
CPU 12: 80731400
CPU 13: 80731400
CPU 14: 80731400
CPU 15: 80731400
CPU 16: 80731400
CPU 17: 80731400
CPU 18: 80731400
CPU 19: 80731400

I then tried to set the offset via Corefreq to +15, but nothing changed, and the MSR reported the same values as well.
While +15 is silently accepted (doing nothing), setting +16 gives instead "Invalid Argument".

[cyring]

The upper bits 0x80XXXXXX are thus meaningless and none Target Offset nor TCC Activation Offset is programmable on your ADL

But can you program the TjMax ?
Although it is specified as read-only in all previous architectures

Something like:

## attempt to set TjMax to 110 C
wrmsr -a 0x1A2 0x806E1400
rdmsr -ax 0x1A2

[BugReporterZ]

It looks like it isn't possible to directly program TjMax in the OS.

# sudo wrmsr -a 0x1A2 0x806E1400
# sudo rdmsr -ax 0x1A2
CPU 0: 80551400
CPU 1: 80551400
CPU 2: 80551400
CPU 3: 80551400
CPU 4: 80551400
CPU 5: 80551400
CPU 6: 80551400
CPU 7: 80551400
CPU 8: 80551400
CPU 9: 80551400
CPU 10: 80551400
CPU 11: 80551400
CPU 12: 80551400
CPU 13: 80551400
CPU 14: 80551400
CPU 15: 80551400
CPU 16: 80551400
CPU 17: 80551400
CPU 18: 80551400
CPU 19: 80551400

[cyring]

Thanks I was expecting those results.

To sum up: my new feature "Thermal Offset" is working for some processors, at least those specified in the Intel SDM; and my Tiger Lake for Laptop for unknown reasons 🤔

[BugReporterZ]

It might be another of those laptop-specific features that aren't enabled on desktop parts.

[cyring]

Preview: IvyBridge

• Offset has a nominal zero value
• Let's add +10 C

• Let's add +5 C more

• With a 15 C offset, Core temperature computes to 12 C

• Let's roll back to a null Thermal Offset
• Apply a minus 15 C to the offset

• Temperature = TjMax - DTS - offset

[cyring]

Preview: Westmere/Gulftown [Nehalem]

• Including commit d944c04 , attempt to add 5 C to the offset

• Processor does not support Thermal Offset from MSR_IA32_TEMPERATURE_TARGET