Re: [PATCH v2 4/6] KVM-GST: KVM Steal time registration

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On 01/28/2011 09:52 PM, Glauber Costa wrote:
Register steal time within KVM. Everytime we sample the steal time
information, we update a local variable that tells what was the
last time read. We then account the difference.



  static void kvm_guest_cpu_offline(void *dummy)
  {
  	kvm_pv_disable_apf(NULL);
+	native_write_msr(MSR_KVM_STEAL_TIME, 0, 0);
  	apf_task_wake_all();
  }

Don't use the native_ versions, they override the pvops implementation. It doesn't matter for kvm, but we're not supposed to know this.

+	/*
+	 * using nanoseconds introduces noise, which accumulates easily
+	 * leading to big steal time values. We want, however, to keep the
+	 * interface nanosecond-based for future-proofness. The hypervisor may
+	 * adopt a similar strategy, but we can't rely on that.
+	 */
+	delta /= NSEC_PER_MSEC;
+	delta *= NSEC_PER_MSEC;

You're working around this problem both in the guest and host. So even if we fix it in one, it will still be broken in the other.

+
+	return delta;
+}
+

--
error compiling committee.c: too many arguments to function

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