KVM: disable halt_poll_ns as default for s390x
We observed some performance degradation on s390x with dynamic
halt polling. Until we can provide a proper fix, let's enable
halt_poll_ns as default only for supported architectures.
Architectures are now free to set their own halt_poll_ns
default value.
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 04146a2..8db1d93 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -66,8 +66,8 @@
MODULE_AUTHOR("Qumranet");
MODULE_LICENSE("GPL");
-/* halt polling only reduces halt latency by 5-7 us, 500us is enough */
-static unsigned int halt_poll_ns = 500000;
+/* Architectures should define their poll value according to the halt latency */
+static unsigned int halt_poll_ns = KVM_HALT_POLL_NS_DEFAULT;
module_param(halt_poll_ns, uint, S_IRUGO | S_IWUSR);
/* Default doubles per-vcpu halt_poll_ns. */