After some further tests I think it could be actually independent of the microcode and rather be kernel 5.3's fault.
First perhaps some notes on that notebook: It's an Fujitsu LIFEBOOK U757 with: model name : Intel(R) Core(TM) i7-7600U CPU @ 2.80GHz When I got the system in around 2017, IIRC, I already had considerable CPU overheating problems seeing often messages like: ov 17 14:41:22 heisenberg kernel: [ 36.347425] mce: CPU2: Core temperature above threshold, cpu clock throttled (total events = 1) Nov 17 14:41:22 heisenberg kernel: [ 36.347426] mce: CPU0: Core temperature above threshold, cpu clock throttled (total events = 1) Nov 17 14:41:22 heisenberg kernel: [ 36.347427] mce: CPU1: Package temperature above threshold, cpu clock throttled (total events = 1) Nov 17 14:41:22 heisenberg kernel: [ 36.347427] mce: CPU3: Package temperature above threshold, cpu clock throttled (total events = 1) Nov 17 14:41:22 heisenberg kernel: [ 36.347429] mce: CPU0: Package temperature above threshold, cpu clock throttled (total events = 1) Nov 17 14:41:22 heisenberg kernel: [ 36.347531] mce: CPU2: Package temperature above threshold, cpu clock throttled (total events = 1) Nov 17 14:41:22 heisenberg kernel: [ 36.348423] mce: CPU2: Core temperature/speed normal Nov 17 14:41:22 heisenberg kernel: [ 36.348424] mce: CPU0: Core temperature/speed normal Nov 17 14:41:22 heisenberg kernel: [ 36.348461] mce: CPU1: Package temperature/speed normal Nov 17 14:41:22 heisenberg kernel: [ 36.348461] mce: CPU3: Package temperature/speed normal Nov 17 14:41:22 heisenberg kernel: [ 36.348498] mce: CPU2: Package temperature/speed normal Nov 17 14:41:22 heisenberg kernel: [ 36.348568] mce: CPU0: Package temperature/speed normal Just with many thousands of events and temperatures reaching pretty exactly 100°C. Fujitsu support had no real solution, claiming it wouldn't happen under Windows. Eventually the solution was to disable the turbo: /sys/devices/system/cpu/intel_pstate/no_turbo = 1 (and all my previous tests as well as the ones from this mail have that set). Since then I rarely see the temperature warnings from above, and if it's usually only exactly one event during boot. I guess the cooling of that slim ultrabook is just not designed well enough to transport enough heat away if the turbo is on. One further constant thing is that playback of videos always lead to considerable CPU utilisation (and higher temperatures), much worse than the previous ~2012 lifebook the university bought me. I've never found a real solution for that,... video decoding acceleration is enabled and seems to work but still,... Suspicion was that it might be some issue in cinnamon, cause the cinnamon process also gets quite high CPU usage when I play back videos. But when I've reported this ticket, things had gotten much worse (and it was like that already for a week till I've took action or even noticed it), especially when the system was basically idle, the temps were also much higher and the fan running much louder/faster. And as I've described before, there are situations when it get's really hot (80° and more) an doesn't cool down again a lot, even if the it becomes idle again. Just before I did some more testing with different kernel/microcode combinations: ************************************************************** With 5.2.17 0xca-2019-09-26: Event/s PID %CPU PR NI Task Init Function 59.82 1730 0.2 0 0 Xorg hrtimer_wakeup 55.83 1730 0.2 0 0 Xorg it_real_fn 14.96 3203 0.5 0 0 gnome-terminal- hrtimer_wakeup 13.96 3086 0.0 0 0 diodon hrtimer_wakeup 7.98 3065 0.2 0 0 cinnamon tick_sched_timer 3.99 3203 0.5 0 0 gnome-terminal- tick_sched_timer 2.99 32 0.0 0 0 [kworker/1:1] intel_uncore_fw_release_timer 1.99 509 0.0 0 0 [kworker/u8:4] intel_uncore_fw_release_timer 1.99 1730 0.2 0 0 Xorg intel_uncore_fw_release_timer 1.99 45 0.0 0 0 [kworker/2:1] intel_uncore_fw_release_timer 1.00 847 0.0 0 0 gmain hrtimer_wakeup 1.00 2861 0.0 0 0 gmain hrtimer_wakeup 1.00 236 0.0 0 0 [kworker/3:2] intel_uncore_fw_release_timer 1.00 751 0.0 0 0 haveged hrtimer_wakeup 1.00 2920 0.0 0 0 gmain hrtimer_wakeup 1.00 1730 0.2 0 0 Xorg tick_sched_timer 1.00 3065 0.3 0 0 cinnamon intel_uncore_fw_release_timer 173 Total events, 172.48 events/sec (kernel: 7.98, userspace: 164.51) Event/s PID %CPU PR NI Task Init Function 68.00 1730 0.5 0 0 Xorg hrtimer_wakeup 65.00 1730 0.5 0 0 Xorg it_real_fn 20.00 3203 0.3 0 0 gnome-terminal- hrtimer_wakeup 14.00 3086 0.0 0 0 diodon hrtimer_wakeup 7.00 3065 0.4 0 0 cinnamon tick_sched_timer 5.00 32 0.0 0 0 [kworker/1:1] intel_uncore_fw_release_timer 4.00 1730 0.5 0 0 Xorg tick_sched_timer 4.00 1730 0.5 0 0 Xorg intel_uncore_fw_release_timer 2.00 751 0.0 0 0 haveged hrtimer_wakeup 1.00 2695 0.0 0 0 ssh-agent hrtimer_wakeup 1.00 3074 0.0 0 0 gdbus tick_sched_timer 1.00 3203 0.3 0 0 gnome-terminal- tick_sched_timer 1.00 145 0.0 0 0 [kworker/0:2] tick_sched_timer 1.00 3104 0.0 0 0 gdbus tick_sched_timer 194 Total events, 194.00 events/sec (kernel: 6.00, userspace: 188.00) Event/s PID %CPU PR NI Task Init Function 63.00 1730 0.5 0 0 Xorg hrtimer_wakeup 61.00 1730 0.5 0 0 Xorg it_real_fn 14.00 3086 0.1 0 0 diodon hrtimer_wakeup 13.00 3203 0.3 0 0 gnome-terminal- hrtimer_wakeup 12.00 3065 0.5 0 0 cinnamon tick_sched_timer 7.00 32 0.0 0 0 [kworker/1:1] intel_uncore_fw_release_timer 5.00 1730 0.5 0 0 Xorg intel_uncore_fw_release_timer 3.00 1730 0.5 0 0 Xorg tick_sched_timer 2.00 173 0.0 0 0 [kworker/u8:3] intel_uncore_fw_release_timer 2.00 3203 0.3 0 0 gnome-terminal- tick_sched_timer 2.00 236 0.5 0 0 [kworker/3:2] intel_uncore_fw_release_timer 1.00 145 0.0 0 0 [kworker/0:2] intel_uncore_fw_release_timer 1.00 751 0.0 0 0 haveged hrtimer_wakeup 1.00 3086 0.0 0 0 diodon tick_sched_timer 187 Total events, 187.00 events/sec (kernel: 12.00, userspace: 175.00) Event/s PID %CPU PR NI Task Init Function 60.00 1730 0.2 0 0 Xorg hrtimer_wakeup 55.00 1730 0.2 0 0 Xorg it_real_fn 16.00 3086 0.1 0 0 diodon hrtimer_wakeup 14.00 3203 0.2 0 0 gnome-terminal- hrtimer_wakeup 7.00 3065 0.2 0 0 cinnamon tick_sched_timer 5.00 32 0.0 0 0 [kworker/1:1] intel_uncore_fw_release_timer 2.00 1730 0.2 0 0 Xorg tick_sched_timer 1.00 3203 0.2 0 0 gnome-terminal- tick_sched_timer 1.00 751 0.0 0 0 haveged hrtimer_wakeup 1.00 3065 0.3 0 0 cinnamon hrtimer_wakeup 1.00 1730 0.2 0 0 Xorg intel_uncore_fw_release_timer 1.00 32 0.0 0 0 [kworker/1:1] tick_sched_timer 1.00 3065 0.4 0 0 cinnamon intel_uncore_fw_release_timer 165 Total events, 165.00 events/sec (kernel: 6.00, userspace: 159.00) Event/s PID %CPU PR NI Task Init Function 65.00 1730 0.5 0 0 Xorg hrtimer_wakeup 61.00 1730 0.5 0 0 Xorg it_real_fn 34.00 3065 1.3 0 0 cinnamon tick_sched_timer 19.00 3086 0.1 0 0 diodon hrtimer_wakeup 14.00 3203 0.2 0 0 gnome-terminal- hrtimer_wakeup 11.00 842 0.0 0 0 NetworkManager tick_sched_timer 8.00 907 0.0 0 0 gdbus tick_sched_timer 8.00 841 0.0 0 0 dbus-daemon tick_sched_timer 5.00 3074 0.7 0 0 gdbus tick_sched_timer 5.00 32 0.0 0 0 [kworker/1:1] intel_uncore_fw_release_timer 4.00 3104 0.2 0 0 gdbus tick_sched_timer 2.00 3203 0.2 0 0 gnome-terminal- tick_sched_timer 2.00 236 0.0 0 0 [kworker/3:2] intel_uncore_fw_release_timer 2.00 841 0.0 0 0 <...> tick_sched_timer 2.00 3086 0.1 0 0 diodon tick_sched_timer 2.00 1730 0.5 0 0 Xorg tick_sched_timer 2.00 3088 0.0 0 0 nm-applet tick_sched_timer 2.00 888 0.0 0 0 wpa_supplicant hrtimer_wakeup 2.00 1730 0.5 0 0 Xorg intel_uncore_fw_release_timer 1.00 751 0.0 0 0 haveged hrtimer_wakeup 251 Total events, 251.00 events/sec (kernel: 7.00, userspace: 244.00) Event/s PID %CPU PR NI Task Init Function 59.30 1730 0.5 0 0 Xorg hrtimer_wakeup 57.29 1730 0.5 0 0 Xorg it_real_fn 23.12 3203 0.0 0 0 gnome-terminal- hrtimer_wakeup 16.08 3086 0.0 0 0 diodon hrtimer_wakeup 7.04 32 0.0 0 0 [kworker/1:1] intel_uncore_fw_release_timer 7.04 3065 0.3 0 0 cinnamon tick_sched_timer 3.02 1730 0.5 0 0 Xorg tick_sched_timer 3.02 1730 0.5 0 0 Xorg intel_uncore_fw_release_timer 2.01 751 0.0 0 0 haveged hrtimer_wakeup 1.01 3203 0.0 0 0 gnome-terminal- tick_sched_timer 178 Total events, 178.89 events/sec (kernel: 7.04, userspace: 171.86) ^C Event/s PID %CPU PR NI Task Init Function 141.84 1730 0.0 0 0 Xorg hrtimer_wakeup 120.57 1730 0.0 0 0 Xorg it_real_fn 85.11 3203 1.8 0 0 gnome-terminal- hrtimer_wakeup 28.37 3203 1.8 0 0 gnome-terminal- tick_sched_timer 14.18 751 0.0 0 0 haveged hrtimer_wakeup 14.18 32 0.0 0 0 [kworker/1:1] intel_uncore_fw_release_timer 7.09 2718 0.0 0 0 <...> hrtimer_wakeup 7.09 7530 0.0 0 0 [kworker/u8:8] tick_sched_timer 7.09 3065 0.8 0 0 cinnamon hrtimer_wakeup 7.09 1730 0.0 0 0 Xorg intel_uncore_fw_release_timer 61 Total events, 432.62 events/sec (kernel: 21.28, userspace: 411.35) => I thought I'd had seen much higher numbers for hrtimer_wakeup when running 5.3, but that didn't turn out to be the case at an idle system (DE/cinnamon running but no real load) root@heisenberg:~# sensors coretemp-isa-0000 Adapter: ISA adapter Package id 0: +54.0°C (high = +100.0°C, crit = +100.0°C) Core 0: +52.0°C (high = +100.0°C, crit = +100.0°C) Core 1: +52.0°C (high = +100.0°C, crit = +100.0°C) iwlwifi-virtual-0 Adapter: Virtual device temp1: +33.0°C update-iniramfs -u -k all barely hits 70°C ************************************************************** ************************************************************** With 5.3.9+0xCA-2019-09-26 eventstat didn't show considerably higher numbers for e.g. hrtimer_wakeup which I thought I'd had seen at first. But now idle system (again cinnamon running) seems to run much hotter, barely getting below 60°: # sensors coretemp-isa-0000 Adapter: ISA adapter Package id 0: +66.0°C (high = +100.0°C, crit = +100.0°C) Core 0: +61.0°C (high = +100.0°C, crit = +100.0°C) Core 1: +61.0°C (high = +100.0°C, crit = +100.0°C) iwlwifi-virtual-0 Adapter: Virtual device temp1: +33.0°C CMB1-acpi-0 Adapter: ACPI interface in0: 16.58 V curr1: 0.00 A Here I did some apt/aptitude stuff to get older an intel-microcode from stable or oldstable. After that (installation of packages and update-initramfs) it took (I'd say) noticeable longer (not extremely much, but noticable) till the CPU cools down to the (still higher base level of) idle temps from above (~60-68°) Running update-initramfs -k all -u let's the temps go easily above 70° up to 85°. Interestingly sometimes it cools down again rather fast (but still only to the 60° range). Sometimes it doesn't. Especially video playpack seems to be a killer. Playing a: Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x304 [SAR 152:151 DAR 360:151], 529 kb/s, SAR 181:180 DAR 181:76, 25 fps, 25 tbr, 25k tbn, 50 tbc (default) in full screen lets the CPU heat up to: # sensors coretemp-isa-0000 Adapter: ISA adapter Package id 0: +93.0°C (high = +100.0°C, crit = +100.0°C) Core 0: +83.0°C (high = +100.0°C, crit = +100.0°C) Core 1: +81.0°C (high = +100.0°C, crit = +100.0°C) iwlwifi-virtual-0 Adapter: Virtual device temp1: +33.0°C CMB1-acpi-0 Adapter: ACPI interface in0: 16.57 V curr1: 0.00 A and it took quite a while to cool down, even though I've stopped the video for a minute or so already. ************************************************************** ************************************************************** With 5.3.9+0xb-2019-04-01: I.e. current kernel, but even older microcode (the last one where I though it was ok, was 3.20191112.1 ... but that might be just a coincidence since on Nov 14 2019 I've installed kernel 5.3 packages, and that is roughly around 3.20191113.1 (Fri, 15 Nov 2019) where I've started to slowly notice the CPU temperature issues. Idle temp sems to be around: # sensors iwlwifi-virtual-0 Adapter: Virtual device temp1: +33.0°C coretemp-isa-0000 Adapter: ISA adapter Package id 0: +71.0°C (high = +100.0°C, crit = +100.0°C) Core 0: +66.0°C (high = +100.0°C, crit = +100.0°C) Core 1: +65.0°C (high = +100.0°C, crit = +100.0°C) CMB1-acpi-0 Adapter: ACPI interface in0: 16.57 V curr1: 0.00 A so here I concluded that maybe 5.3 is the offender... and not the microcode!? Installing the current microcode again and afterwards doing: update-initramfs -k all -u leads to temps around that: $ sensors iwlwifi-virtual-0 Adapter: Virtual device temp1: +33.0°C coretemp-isa-0000 Adapter: ISA adapter Package id 0: +79.0°C (high = +100.0°C, crit = +100.0°C) Core 0: +74.0°C (high = +100.0°C, crit = +100.0°C) Core 1: +79.0°C (high = +100.0°C, crit = +100.0°C) CMB1-acpi-0 Adapter: ACPI interface in0: 16.57 V curr1: 0.00 A staying long at around: iwlwifi-virtual-0 Adapter: Virtual device temp1: +33.0°C coretemp-isa-0000 Adapter: ISA adapter Package id 0: +74.0°C (high = +100.0°C, crit = +100.0°C) Core 0: +68.0°C (high = +100.0°C, crit = +100.0°C) Core 1: +66.0°C (high = +100.0°C, crit = +100.0°C) CMB1-acpi-0 Adapter: ACPI interface in0: 16.57 V curr1: 0.00 A even though the initrd creation is already long over and top shows nothing else. ************************************************************** I'm now back at running 5.2.17-1 (2019-10-06) from the linux-image-5.2.0-3-amd64-unsigned package with the most recent intel-microcode package version. Temperatures seem good (in the sense: as from before I noticed issues). So my conclusion would be 5.3 is the bad boy... Shall we reassign it to src:linux? Cheers, Chris.