From 7a7708a0554385299fbc204969cdf65a91964c27 Mon Sep 17 00:00:00 2001 From: Ben Pfaff Date: Mon, 14 May 2012 11:13:39 -0700 Subject: [PATCH] ovs-vswitchd: Document some limits. Signed-off-by: Ben Pfaff --- vswitchd/ovs-vswitchd.8.in | 43 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/vswitchd/ovs-vswitchd.8.in b/vswitchd/ovs-vswitchd.8.in index 6c9f3e4a..bfd70fbd 100644 --- a/vswitchd/ovs-vswitchd.8.in +++ b/vswitchd/ovs-vswitchd.8.in @@ -207,6 +207,49 @@ enabled. .so ofproto/ofproto-unixctl.man .so lib/vlog-unixctl.man .so lib/stress-unixctl.man +. +.SH "LIMITS" +. +.PP +We believe these limits to be accurate as of this writing. These +limits assume the use of the Linux kernel datapath. +. +.IP \(bu +Approximately 256 bridges given the allowance of 5,000 file +descriptors that \fBovs\-ctl\fR(8) configures. (\fBovs\-vswitchd\fR +requires 17 file descriptors per datapath.) +. +.IP \(bu +65,280 ports per bridge. Performance will degrade beyond 1,024 ports +per bridge due to fixed hash table sizing. +. +.IP \(bu +2,048 MAC learning entries per bridge. +. +.IP \(bu +Kernel flows are limited only by memory available to the kernel. +Performance will degrade beyond 1,048,576 kernel flows per bridge with +a 32-bit kernel, beyond 262,144 with a 64-bit kernel. +(\fBovs\-vswitchd\fR should never install anywhere near that many +flows.) +. +.IP \(bu +OpenFlow flows are limited only by available memory. Performance is +linear in the number of unique wildcard patterns. That is, an +OpenFlow table that contains many flows that all match on the same +fields in the same way has a constant-time lookup, but a table that +contains many flows that match on different fields requires lookup +time linear in the number of flows. +. +.IP \(bu +255 ports per bridge participating in 802.1D Spanning Tree Protocol. +. +.IP \(bu +32 mirrors per bridge. +. +.IP \(bu +15 bytes for the name of a port. (This is a Linux kernel limitation.) +. .SH "SEE ALSO" .BR ovs\-appctl (8), .BR ovs\-brcompatd (8), -- 2.30.2