This adds ability to expose host CPU power management capabilities to
guests. For intel guests, this is sufficient for guest to enable
low power CPU power management. For AMD guests it isn't sufficient,
deeper C-states are entered using System-IO.
mwait based power management is tied closely to specifics of CPUID,
making migration challenging. At this point only the non-migrateable
-cpu host is supported.
With this patch applied, VM latency is within the noise of
baremetal for some benchmarks.
perf bench sched pipe results:
Before:
6.452 sec
After:
4.382 sec
Baremetal:
4.136 sec
Michael S. Tsirkin (2):
kvm: support -realtime cpu-pm=on|off
i386/cpu: make -cpu host support monitor/mwait
include/sysemu/sysemu.h | 1 +
target/i386/cpu.h | 9 +++++++++
target/i386/cpu.c | 19 ++++++++++++++-----
target/i386/kvm.c | 30 ++++++++++++++++++++++++++++++
vl.c | 6 ++++++
qemu-options.hx | 9 +++++++--
6 files changed, 67 insertions(+), 7 deletions(-)
--
MST
