Wanpeng Li <kernellwp@xxxxxxxxx> writes: > From: Wanpeng Li <wanpengli@xxxxxxxxxxx> > > 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@xxxxxxxxxxx> > --- > v3 -> v4: > * check vcpu->vcpu_idx > > 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 (vcpu->vcpu_idx == 0) > + schedule_delayed_work(&kvm->arch.kvmclock_sync_work, > + KVMCLOCK_SYNC_PERIOD); > } > > void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) Forgive me my ignorance, I was under the impression schedule_delayed_work() doesn't do anything if the work is already queued (see queue_delayed_work_on()) and we seem to be scheduling the same work (&kvm->arch.kvmclock_sync_work) which is per-kvm (not per-vcpu). Do we actually happen to finish executing it before next vCPU is created or why does the storm you describe happens? -- Vitaly
