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KVM: disable halt_poll_ns as default for s390x

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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>
This commit is contained in:
David Hildenbrand
2015-09-18 12:34:53 +02:00
committed by Paolo Bonzini
parent 58c95070da
commit 920552b213
7 changed files with 8 additions and 2 deletions
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4
virt/kvm/kvm_main.c
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@@ -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. */