Fast sleep is a deep idle state on Power8. The support for the state was
added in commit 0d94873011. Today the idle threads in the host can
potentially be put to fast sleep. But when we launch guests using kvm,
the secondary threads are required to be offline and the offline threads
are put to nap. Besides this case, when secondary threads are woken up
to run guests and eventually go idle or when the guest is killed, they
enter nap. So when the entire core goes idle in both the above scenarios,
the maximum power savings that we can obtain is as much as we can get from
napping the cpus. This patchset adds support in the above two cases
for the threads to enter fast sleep.
---
Srivatsa S. Bhat (6):
powernv, cpuidle: Move the flags used for idle state discovery to powernv
core
powerpc, powernv, CPU hotplug: Put offline CPUs in Fast-Sleep instead of
Nap
KVM: PPC: Book3S HV: Enable CPUs to run guest after waking up from
fast-sleep
KVM: PPC: Book3S HV: Consolidate the idle-state enter sequence in KVM
KVM: PPC: Book3S HV: Put KVM standby hwthreads to fast-sleep instead of
nap
ppc,book3s: Go back to same idle state after handling machine check
interrupt
arch/powerpc/include/asm/processor.h | 12 ++++
arch/powerpc/kernel/exceptions-64s.S | 51 +++++++++------
arch/powerpc/kernel/idle.c | 52 ++++++++++++++++
arch/powerpc/kernel/idle_power7.S | 2 -
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 103 ++++++++++++++++++++++++-------
arch/powerpc/platforms/powernv/smp.c | 12 +++-
drivers/cpuidle/cpuidle-powernv.c | 7 +-
7 files changed, 190 insertions(+), 49 deletions(-)
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