Merge remote-tracking branch 'ovs-dev/master'

[sliver-openvswitch.git] / FAQ

diff --git a/FAQ b/FAQ
index 8b1ccb4..4a8a5be 100644 (file)
--- a/FAQ
+++ b/FAQ
@@ -89,10 +89,9 @@ A: Distributed vswitch applications (e.g., VMware vNetwork distributed
    environments: OpenFlow, which exposes flow-based forwarding state,
    and the OVSDB management protocol, which exposes switch port state.
    In addition to the switch implementation itself, Open vSwitch
-   includes tools (ovs-controller, ovs-ofctl, ovs-vsctl) that developers
-   can script and extend to provide distributed vswitch capabilities
-   that are closely integrated with their virtualization management
-   platform.
+   includes tools (ovs-ofctl, ovs-vsctl) that developers can script and
+   extend to provide distributed vswitch capabilities that are closely
+   integrated with their virtualization management platform.
 
 Q: Why doesn't Open vSwitch support distribution?
 
@@ -469,6 +468,27 @@ A: Open vSwitch uses different kinds of flows for different purposes:
         regardless of the type.
 
 
+Performance
+-----------
+
+Q: I just upgraded and I see a performance drop.  Why?
+
+A: The OVS kernel datapath may have been updated to a newer version than
+   the OVS userspace components.  Sometimes new versions of OVS kernel
+   module add functionality that is backwards compatible with older
+   userspace components but may cause a drop in performance with them.
+   Especially, if a kernel module from OVS 2.1 or newer is paired with
+   OVS userspace 1.10 or older, there will be a performance drop for
+   TCP traffic.
+
+   Updating the OVS userspace components to the latest released
+   version should fix the performance degradation.
+
+   To get the best possible performance and functionality, it is
+   recommended to pair the same versions of the kernel module and OVS
+   userspace.
+
+
 Configuration Problems
 ----------------------