Bug 9768

Summary:	acpi should be enabled by default for kvm guest
Product:	ACPI	Reporter:	Oleksij Rempel (fishor) (bug-track)
Component:	ACPICA-Core	Assignee:	acpi_acpica-core (acpi_acpica-core)
Status:	CLOSED PATCH_ALREADY_AVAILABLE
Severity:	normal	CC:	acpi-bugzilla
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	2.6.x	Subsystem:
Regression:	---	Bisected commit-id:
Attachments:	messages.log

Description Oleksij Rempel (fishor) 2008-01-17 02:19:59 UTC

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)

Comment 1 Oleksij Rempel (fishor) 2008-01-17 02:28:37 UTC

Created attachment 14485 [details]
messages.log

Comment 2 Zhang Rui 2008-03-24 01:57:51 UTC

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. :)

Comment 3 Oleksij Rempel (fishor) 2008-03-24 05:21:12 UTC

Sorry Zhang, KVM/Qemu provide now DMI. So, no need to change ACPI now.