On Wed, Aug 11 2021 at 15:51, blinkin@xxxxxxxx wrote:
> 1) You're booting with an out of tree module
>
> Uninstalled virtualbox, reproduced same behavior without the module.
> dmesg outputs attached with and without the workaround
> (dmesg_novboxdrv_clean.txt and dmesg_novboxdrv_irqaffinity0.txt)
Ok.
> 2) Please provide information what is consuming 90% of a CPU
>
> top shows a kworker process consistently at 50% without the
> workaround, 60% with the workaround. No significant activity amounts
> from other processes. Sometimes that 50% is split between two
> kworker processes for a short time. CPU core #0 activity is a
> constant 60% without the workaround, 90% with the workaround
That's broken. /proc/interrupts gives some hint:
1) Stock kernel
> CPU0 CPU1 CPU2 CPU3
> 0: 10 0 0 0 IR-IO-APIC 2-edge timer
> 1: 0 0 0 9 IR-IO-APIC 1-edge i8042
> 8: 0 1 0 0 IR-IO-APIC 8-edge rtc0
> 9: 0 923411 0 0 IR-IO-APIC 9-fasteoi acpi
900k ACPI interrupts right after boot
> CPU0 CPU1 CPU2 CPU3
> 0: 10 0 0 0 IR-IO-APIC 2-edge timer
> 1: 0 0 0 11 IR-IO-APIC 1-edge i8042
> 8: 0 1 0 0 IR-IO-APIC 8-edge rtc0
> 9: 0 4869059 0 0 IR-IO-APIC 9-fasteoi acpi
One minute later it's 4.8M
With affinity forced to CPU0 it's even more:
> CPU0 CPU1 CPU2 CPU3
> 0: 10 0 0 0 IR-IO-APIC 2-edge timer
> 1: 9 0 0 0 IR-IO-APIC 1-edge i8042
> 8: 1 0 0 0 IR-IO-APIC 8-edge rtc0
> 9: 7576456 0 0 0 IR-IO-APIC 9-fasteoi acpi
7.5M right after boot
> CPU0 CPU1 CPU2 CPU3
> 0: 10 0 0 0 IR-IO-APIC 2-edge timer
> 1: 11 0 0 0 IR-IO-APIC 1-edge i8042
> 8: 1 0 0 0 IR-IO-APIC 8-edge rtc0
> 9: 10992420 0 0 0 IR-IO-APIC 9-fasteoi acpi
10.9M after one minute. Though the delta between right after boot and 1
minute later is in the same ballpark.
Cc'ed the ACPI people for clues.
Thanks,
tglx
