From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
---
docs/formatdomain.html.in | 25 ++++++++++++++++++++-----
1 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 814e270..c2eabc5 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -1016,11 +1016,23 @@
</dd>
<dt><code>tickpolicy</code></dt>
<dd>
- The <code>tickpolicy</code> attribute determines how
- missed ticks in the guest are handled, and can be "delay",
- "catchup", "merge", or "discard". If the policy is
- "catchup", there can be further details in
- the <code>catchup</code> sub-element.
+ <p>
+ The <code>tickpolicy</code> attribute determines what
+ happens whens QEMU misses a deadline for injecting a
+ tick to the guest:
+ </p>
+ <dl>
+ <dt><code>delay</code></dt>
+ <dd>Continue to deliver ticks at the normal rate. The guest time will be delayed due to the late tick</dd>
+ <dt><code>catchup</code></dt>
+ <dd>Deliver ticks at a higher rate to catchup with the missed tick. The guest time should not be delayed once catch is complete.</dd>
+ <dt><code>merge</code></dt>
+ <dd>Merge the missed tick(s) into one tick and inject. The guest time may be delayed, depending on how the OS reacts to the merging of ticks</dd>
+ <dt><code>discard</code></dt>
+ <dd>Throw away the missed tick(s) and continue with future injection normally. The guest time may be delayed, unless the OS has explicit handling of lost ticks</dd>
+ </dl>
+ <p>If the policy is "catchup", there can be further details in
+ the <code>catchup</code> sub-element.</p>
<dl>
<dt><code>catchup</code></dt>
<dd>
@@ -1030,6 +1042,9 @@
and <code>limit</code>.
</dd>
</dl>
+ <p>
+ Note that hypervisors are not required to support all policies across all time sources
+ </p>
</dd>
<dt><code>frequency</code></dt>
<dd>
--
1.7.7.6
--
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