I found a solution for this, at least for my case! I traced the CPU pinning to ACPI GPE11 (corresponding to IRQ9 in my Mac Pro 1,1) being hit constantly.
This can be killed permanently by passing "acpi_mask_gpe=0x11" to the kernel at boot.
I still believe this was first triggered for 20.04 first during the generic 5.11-5.13 transition and then later during the low-latency 5.13-5.15 transition using the official Ubuntu kernels. I still haven't been able to pinpoint if this was a config change's fault, or perhaps whether a microcode error crept in.
I found a solution for this, at least for my case! I traced the CPU pinning to ACPI GPE11 (corresponding to IRQ9 in my Mac Pro 1,1) being hit constantly.
This can be killed permanently by passing "acpi_mask_ gpe=0x11" to the kernel at boot.
I still believe this was first triggered for 20.04 first during the generic 5.11-5.13 transition and then later during the low-latency 5.13-5.15 transition using the official Ubuntu kernels. I still haven't been able to pinpoint if this was a config change's fault, or perhaps whether a microcode error crept in.
Suggest people give this a go. It clearly works for some others. For more background see here: /unix.stackexch ange.com/ questions/ 588018/ kworker- thread- kacpid- notify- kacpid- hogging- 60-70-of- cpu
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Also a couple of posts here: /mattgadient. com/linux- dvd-images- and-how- to-for- 32-bit- efi-macs- late-2006- models/
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