if CONFIG_ACPI_BLACKLIST_YEAR used ( most distributions use it, like ubuntu ... ) on kvm/qemu guest, acpi will be disabled. So this will couse more interrupts on host system. It seems to be easyer to add exeption for qemu/kvm acpi in acpi/blacklist.c als to add DMI for kvm. Results of powertop: kvm guest with acpi forced Wakeups-from-idle per second : 107,1 interval: 15,0s Top causes for wakeups: 55,2% ( 68,5) qemu-system-x86 : sys_timer_settime (posix_timer_fn) 8,2% ( 10,2) qemu-system-x86 : start_apic_timer (apic_timer_fn) kvm guest without acpi Wakeups-from-idle per second : 191,4 interval: 15,0s Top causes for wakeups: 54,4% (168,3) qemu-system-x86 : sys_timer_settime (posix_timer_fn) 32,3% (100,0) qemu-system-x86 : __kvm_migrate_apic_timer (apic_timer_fn)
Created attachment 14485 [details] messages.log
Sorry that I'm not familiar with KVM, is there already a patch? If so, we'd better send it to acpi-devel for reviewing. :)
Sorry Zhang, KVM/Qemu provide now DMI. So, no need to change ACPI now.