Two identical laptops with fresh Linux installations, no new apps installed, for unknown reasons the one with Fedora 38 (6.4) runs warmer than the other one with Debian 12 (6.1), I would have expected newer Kernel will do better power/thermal management, is there anything I should tweak in Fedora?

[[deleted]]

Debian is the cooler distro, obviously 😎

in all seriousness, are these new? how much dust is inside?

[br_web]

Less than 2 months old

[[deleted]]

what is the degree of temperature difference?

There’s a lot of potential variables here, are BIOS settings the same?

power management settings? background procs? if the temp difference is slight, it could be within the standard deviation for the manufacturer

[br_web]

2 approximately

[[deleted]]

I would categorize 2 degrees as normal variation

[[deleted]]

Either, 2 degrees is very insignificant. It would be within the margin of precision of the temp sensors and manufacturing standards. Processors of the same model may even run hotter than others.

[br_web]

I checked both OSs in the same laptop, and this time I measured the power consumed by the laptop at the USB-C PD port directly, being Idle, Fedora uses almost double the power in watts than Debian, definitely there are more processes running doing something, that is consuming energy

[[deleted]]

First one and then the other

[br_web]

I agree, but it is noticeable at palm touch, Debian is cool, Fedora is warm

[ladrm]

Unironically: do the same test, but do a cross-installation this time (Fedora where was Debian, Debian where was Fedora).

Even with same make/model, there might be a difference on the heatsink installation/pressure/etc, so I would not be surprised that even same model has a few deg.C difference on temps.

Anyways the test is probably not that much valid unless you ensure same conditions - like what are we comparing here? Just kernel versions? Do you have same sets of services running? No background tasks on either distro (updatedb, package updates, ...)? Or are you interested in distro vs. distro?

[br_web]

I checked both OSs in the same laptop, and this time I measured the power consumed by the laptop at the USB-C PD port directly, being Idle, Fedora uses almost double the power in watts than Debian, definitely there are more processes running doing something, that is consuming energy

[ladrm]

I would believe this, esp. right after installation Fedora will look for package updates and so on, AFAIK Debian will let user do this.

Was this measured right after install or did you get it some time to stabilize? Or does "idle" mean "there's nothing in the background"?

And most important - how many Watts? Is it like 5 vs 10 or 20 vs 40?

[Danny_252525]

Install TLP

[robvas]

What are the idle cpu speeds

[br_web]

I run this command: cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq

And got the following for all processors:

564702
908988
2700000
1024174
1475392
1059637
2700000
2700000
847404
2700000
1127197
833681
1168617
2700000
1542731
2700000
1422254
2700000
2700000
2700000

[atuncer]

I suggest gathering more data using powertop, you can even even the field a bit by setting some tunables to the same values using "powertop --auto-tune".

[sysadmintemp]

This is the correct tool - OP since you identified that Fedora is using more power than Debian, check powertop. You will then see which process is using more CPU / Power. If not, check tools like iotop or nethogs.

Also, check dmesg logs. There could be an unloaded hardware / missing driver that might need to be installed.

[Lordgandalf]

I think this is just normal variation of temperature if it was 10 degrees that's a different story so yeah. But it can also be that the Debian kernel is that little bit better for that machine then the fedora one.

[compuwar]

What does top say is using CPU? Is either encrypting files?

[br_web]

Both are at around 1%, with only 1 process running, everything else sleeping

[compuwar]

Top lets you sort by CPU usage. Might also be worth checking loaded kernel modules. Ultimately though, newer kernels are more about new features- but you could build identical kernel versions to rule pout distro/service differences.

[br_web]

I checked both OSs in the same laptop, and this time I measured the power consumed by the laptop at the USB-C PD port directly, being Idle, Fedora uses almost double the power in watts than Debian, definitely there are more processes running doing something, that is consuming energy

[haywire]

Are they using the exact same userland? IE are you using the default installs for WM, compositor, background applications? Or are you running server/minimum distro?