diff options
| author | Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> | 2016-11-02 05:08:35 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-11-22 12:48:08 +0100 |
| commit | 0b9f6c4615c993d2b552e0d2bd1ade49b56e5beb (patch) | |
| tree | ad86293bc792f8035ff78421370793da8c786868 /arch/x86/kvm | |
| parent | 4ec6e863625625a54f527464ab91ce1a1cb16c42 (diff) | |
| download | linux-0b9f6c4615c993d2b552e0d2bd1ade49b56e5beb.tar.bz2 | |
x86/kvm: Support the vCPU preemption check
Support the vcpu_is_preempted() functionality under KVM. This will
enhance lock performance on overcommitted hosts (more runnable vCPUs
than physical CPUs in the system) as doing busy waits for preempted
vCPUs will hurt system performance far worse than early yielding.
Use struct kvm_steal_time::preempted to indicate that if a vCPU
is running or not.
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: boqun.feng@gmail.com
Cc: borntraeger@de.ibm.com
Cc: bsingharora@gmail.com
Cc: dave@stgolabs.net
Cc: jgross@suse.com
Cc: kernellwp@gmail.com
Cc: konrad.wilk@oracle.com
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: rkrcmar@redhat.com
Cc: virtualization@lists.linux-foundation.org
Cc: will.deacon@arm.com
Cc: xen-devel-request@lists.xenproject.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1478077718-37424-9-git-send-email-xinhui.pan@linux.vnet.ibm.com
[ Typo fixes. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/x86.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 04c5d96b1d67..59c2d6f1b131 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2071,6 +2071,8 @@ static void record_steal_time(struct kvm_vcpu *vcpu) &vcpu->arch.st.steal, sizeof(struct kvm_steal_time)))) return; + vcpu->arch.st.steal.preempted = 0; + if (vcpu->arch.st.steal.version & 1) vcpu->arch.st.steal.version += 1; /* first time write, random junk */ @@ -2826,8 +2828,22 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu); } +static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu) +{ + if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED)) + return; + + vcpu->arch.st.steal.preempted = 1; + + kvm_write_guest_offset_cached(vcpu->kvm, &vcpu->arch.st.stime, + &vcpu->arch.st.steal.preempted, + offsetof(struct kvm_steal_time, preempted), + sizeof(vcpu->arch.st.steal.preempted)); +} + void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) { + kvm_steal_time_set_preempted(vcpu); kvm_x86_ops->vcpu_put(vcpu); kvm_put_guest_fpu(vcpu); vcpu->arch.last_host_tsc = rdtsc(); |