Commit 3553ae56 authored by Waiman Long's avatar Waiman Long Committed by Paolo Bonzini

x86/kvm: Don't use pvqspinlock code if only 1 vCPU

On a VM with only 1 vCPU, the locking fast path will always be
successful. In this case, there is no need to use the the PV qspinlock
code which has higher overhead on the unlock side than the native
qspinlock code.
Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 450917b6
......@@ -748,6 +748,10 @@ void __init kvm_spinlock_init(void)
if (kvm_para_has_hint(KVM_HINTS_REALTIME))
return;
/* Don't use the pvqspinlock code if there is only 1 vCPU. */
if (num_possible_cpus() == 1)
return;
__pv_init_lock_hash();
pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
......
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