[PATCH v2 4/4] docs: documentation for virtio packed option

Bjoern Walk bwalk at linux.ibm.com
Mon Apr 6 13:13:27 UTC 2020

Reviewed-by: Boris Fiuczynski <fiuczy at linux.ibm.com>
Signed-off-by: Bjoern Walk <bwalk at linux.ibm.com>
 docs/formatdomain.html.in | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index fbffb168..f0252a34 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -4372,6 +4372,16 @@
       Possible values are <code>on</code> or <code>off</code>.
       <span class="since">Since 3.5.0</span>
+    <p>
+      The attribute <code>packed</code> controls if QEMU should try to use
+      packed virtqueues. Compared to regular split queues, packed queues
+      consist of only a single descriptor ring replacing available and used
+      ring, index and descriptor buffer. This can result in better cache
+      utilization and performance. If packed virtqueues are actually used
+      depends on the feature negotiation between QEMU, vhost backends and guest
+      drivers. Possible values are <code>on</code> or <code>off</code>.
+      <span class="since">Since 6.3.0 (QEMU and KVM only)</span>
+    </p>
     <h4><a id="elementsVirtioTransitional">Virtio transitional devices</a></h4>

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