[ovs-dev] [PATCH v2] Document per-port round-robin during controller rate limiting.

Ben Pfaff blp at nicira.com
Wed Sep 23 19:40:31 UTC 2009

CC: Peter Balland <peter at nicira.com>

Bug #2072.
This integrates Justin's feedback on v1.

diff --git a/vswitchd/ovs-vswitchd.conf.5.in b/vswitchd/ovs-vswitchd.conf.5.in
index 12fea6c..ed6ad00 100644
--- a/vswitchd/ovs-vswitchd.conf.5.in
+++ b/vswitchd/ovs-vswitchd.conf.5.in
@@ -547,6 +547,19 @@ These settings configure how the virtual switch applies a ``token
 bucket'' to limit the rate at which packets in unknown flows are
 forwarded to the OpenFlow controller for flow-setup processing.  This
 feature prevents a single bridge from overwhelming a controller.
+In addition, when a high rate triggers rate-limiting,
+\fBovs\-vswitchd\fR queues controller packets for each port and
+transmits them to the controller at the configured rate.  The number
+of queued packets is limited by a ``burst size'' parameter.  The
+packet queue is shared fairly among the ports on a bridge.
+\fBovs\-vswitchd\fR maintains two such packet rate-limiters per
+bridge.  One of these applies to packets sent up to the controller
+because they do not correspond to any flow.  The other applies to
+packets sent up to the controller by request through flow actions.
+When both rate-limiters are filled with packets, the actual rate that
+packets are sent to the controller is up to twice the specified rate.
 .IP "\fBbridge.\fIname\fB.controller.rate-limit=\fIrate\fR"
 .IQ "\fBmgmt.rate-limit=\fIrate\fR"
 Limits the maximum rate at which packets will be forwarded to the

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