| Message ID | 1282053481-18787-22-git-send-email-agraf@suse.de (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Tue, 17 Aug 2010 15:57:56 +0200 Alexander Graf <agraf@suse.de> wrote: > There are some heuristics in the PPC power management code that try to find > out if the particular hardware we're running on supports proper power management > or just hangs the machine when going into nap mode. > > Since we know that KVM is safe with nap, let's force enable it in the PV code > once we're certain that we are on a KVM VM. Could this cause the cache to be flushed unnecessarily on e500? Where available, doze would probably be better for signalling the hypervisor that the guest is idle. > > Signed-off-by: Alexander Graf <agraf@suse.de> > --- > arch/powerpc/kernel/kvm.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c > index 517da39..95aed6b 100644 > --- a/arch/powerpc/kernel/kvm.c > +++ b/arch/powerpc/kernel/kvm.c > @@ -583,6 +583,9 @@ static int __init kvm_guest_init(void) > if (kvm_para_has_feature(KVM_FEATURE_MAGIC_PAGE)) > kvm_use_magic_page(); > > + /* Enable napping */ > + powersave_nap = 1; > + > free_tmp: > kvm_free_tmp(); >
On 17.08.2010, at 20:28, Scott Wood wrote: > On Tue, 17 Aug 2010 15:57:56 +0200 > Alexander Graf <agraf@suse.de> wrote: > >> There are some heuristics in the PPC power management code that try to find >> out if the particular hardware we're running on supports proper power management >> or just hangs the machine when going into nap mode. >> >> Since we know that KVM is safe with nap, let's force enable it in the PV code >> once we're certain that we are on a KVM VM. > > Could this cause the cache to be flushed unnecessarily on e500? Where > available, doze would probably be better for signalling the hypervisor > that the guest is idle. You're right - this should be #ifdef'ed on Book3s. I'll add that as a patch on top, as Qemu on BookE doesn't expose KVM capabilities yet. Alex
diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c index 517da39..95aed6b 100644 --- a/arch/powerpc/kernel/kvm.c +++ b/arch/powerpc/kernel/kvm.c @@ -583,6 +583,9 @@ static int __init kvm_guest_init(void) if (kvm_para_has_feature(KVM_FEATURE_MAGIC_PAGE)) kvm_use_magic_page(); + /* Enable napping */ + powersave_nap = 1; + free_tmp: kvm_free_tmp();
There are some heuristics in the PPC power management code that try to find out if the particular hardware we're running on supports proper power management or just hangs the machine when going into nap mode. Since we know that KVM is safe with nap, let's force enable it in the PV code once we're certain that we are on a KVM VM. Signed-off-by: Alexander Graf <agraf@suse.de> --- arch/powerpc/kernel/kvm.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)