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Date: Mon, 17 Feb 2020 18:36:41 +0800 From: Wanpeng Li <kernellwp@...il.com> To: LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org> Cc: Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson <sean.j.christopherson@...el.com>, Wanpeng Li <wanpengli@...cent.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, Jim Mattson <jmattson@...gle.com>, Joerg Roedel <joro@...tes.org> Subject: [PATCH v3 1/2] KVM: X86: Less kvmclock sync induced vmexits after VM boots From: Wanpeng Li <wanpengli@...cent.com> In the progress of vCPUs creation, it queues a kvmclock sync worker to the global workqueue before each vCPU creation completes. Each worker will be scheduled after 300 * HZ delay and request a kvmclock update for all vCPUs and kick them out. This is especially worse when scaling to large VMs due to a lot of vmexits. Just one worker as a leader to trigger the kvmclock sync request for all vCPUs is enough. Signed-off-by: Wanpeng Li <wanpengli@...cent.com> --- arch/x86/kvm/x86.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index fb5d64e..d0ba2d4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9390,8 +9390,9 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu) if (!kvmclock_periodic_sync) return; - schedule_delayed_work(&kvm->arch.kvmclock_sync_work, - KVMCLOCK_SYNC_PERIOD); + if (kvm->created_vcpus == 1) + schedule_delayed_work(&kvm->arch.kvmclock_sync_work, + KVMCLOCK_SYNC_PERIOD); } void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) -- 2.7.4
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