3 .TH ovs\-benchmark 1 "July 2011" "Open vSwitch" "Open vSwitch Manual"
6 ovs\-benchmark \- flow setup benchmark utility for Open vSwitch
10 .SY ovs\-benchmark\ latency
11 \fB\-\-remote \fIip\fR[\fB:\fIports\fR]
12 .OP \-\-sockets nsocks
13 .OP \-\-batches nbatches
14 .OP \-\-local \fR[\fIip\fR][\fB:\fIports\fR]
17 .SY ovs\-benchmark\ rate
18 \fB\-\-remote \fIip\fR[\fB:\fIports\fR]
19 .OP \-\-max\-rate rate
20 .OP \-\-timeout maxsecs
21 .OP \-\-sockets nsocks
22 .OP \-\-batches nbatches
23 .OP \-\-local \fR[\fIip\fR][\fB:\fIports\fR]
26 .SY ovs\-benchmark\ listen
27 .OP \-\-local \fR[\fIip\fR]\fB:\fIports
30 .SY ovs\-benchmark\ help
34 \fBovs\-benchmark\fR tests the performance of Open vSwitch flow setup
35 by setting up a number of TCP connections and measuring the time
36 required. It can also be used with the Linux bridge or without any
37 bridging software, which allows one to measure the bandwidth and
38 latency cost of bridging.
40 Each \fBovs\-benchmark\fR command is described separately below.
42 .SH "The ``latency'' command"
45 This command initiates \fInsocks\fR TCP connections (by default, 100)
46 as quickly as possible, waits for each one to complete with success or
47 failure, and prints a bar chart of completion times on standard
48 output, followed by a summary line. Each line in the bar chart lists
49 a time to connection completion in milliseconds followed by a number
50 of \fB.\fR or \fB!\fR symbols, one for each TCP connection that
51 completed in that many milliseconds. A successful connection prints a
52 \fB.\fR, and an unsuccessful connection (e.g. to a port on which no
53 process is listening) prints a \fB!\fR.
56 If \fInbatches\fR is given, the entire procedure is repeated the
57 specified number of times. Only a single summary line is printed at
61 Results vary widely based on the number of sockets and whether the
62 remote host is listening for connections on the specified ports. With
63 a small number of sockets, all connection times typically remain
64 within a handful of milliseconds. As the number of sockets increases,
65 the distribution of connection times clusters around the sending TCP
66 stack's SYN retransmission interval. (This pattern occurs with or
67 without Open vSwitch on the network path.)
69 .SH "The ``rate'' command"
72 This command initiates \fInsocks\fR TCP connections (by default, 100)
73 as quickly as possible (limited by \fImaxrate\fR, if
74 \fB\-\-max\-rate\fR is specified). Each time a connection completes
75 with success or failure, it closes that connection and initiates a new
76 one. It continues to do so either forever or, if \fB\-\-timeout\fR is
77 specified, until \fImaxsecs\fR seconds have elapsed. During the test,
78 it prints statistics about time elapsed, successful and unsuccessful
79 connections, and the average number of completed (succeeded or failed)
80 connections per second over the run.
83 Without \fB\-\-max\-rate\fR, the \fBrate\fR command measures the
84 maximum sustained flow setup rate for an Open vSwitch instance. This
85 naturally tends to drive \fBovs\-vswitchd\fR CPU usage to 100% on the
86 host receiving the traffic.
89 When \fB\-\-max\-rate\fR is specified with a value below the maximum
90 rate that an Open vSwitch instance can handle, then \fBrate\fR can
91 also be used to measure the kernel and userspace CPU cost of flow
92 setups at specific flow rates.
95 Results tend to fluctuate greatly for the first few seconds of a run,
96 then settle down. The displayed average is calculated over the entire
97 run and so tends to converge asymptotically on the ``correct'' value.
98 To converge more quickly, try running for 5 to 10 seconds, then
99 killing and restarting the run.
101 .SH "The ``listen'' command"
104 This command listens on one or more TCP ports for incoming
105 connections. It accepts connections and immediately closes them. It
106 can be paired with the \fBrate\fR or \fBlatency\fR commands for
107 observing effects of successful vs. unsuccessful TCP connections.
110 It is easier to reproduce and interpret \fBovs\-benchmark\fR results
111 when there is no listener (see \fBNOTES\fR below).
113 .SH "The ``help'' command"
116 Prints a usage message and exits successfully.
120 .IP "\fB\-r \fIip\fR[\fB:\fIports\fR]"
121 .IQ "\fB\-\-remote \fIip\fR[\fB:\fIports\fR]"
122 This option, required on \fBlatency\fR and \fBrate\fR commands,
123 minimally specifies the remote host to connect to (as an IP address or
124 DNS name) as \fIip\fR.
127 A TCP port or range of ports (separated by \fB\-\fR) may also be
128 specified. If a range is specified then each port in the range is
129 used in round-robin order. The default port is 6630 if none is
132 .IP "\fB\-l \fR[\fIip\fR][\fB:\fIports\fR]"
133 .IQ "\fB\-\-local \fR[\fIip\fR][\fB:\fIports\fR]"
134 On the \fBlatency\fR and \fBrate\fR, without this option, outgoing
135 connections will not bind a specific TCP port. The local TCP stack
136 will pick a local TCP port to bind. When this option is specified,
137 the specified port or range of ports will be used in turn. (If a port
138 range is specified on both \fB\-\-local\fR and \fB\-\-remote\fR, then
139 each local port in its range will be used before the remote port is
140 incremented to the next port in its range.)
143 On the \fBlisten\fR command, this option specifies the local port or
144 ports and IP addresses on which to listen. If it is omitted, port
145 6630 on any IP address is used.
147 .IP "\fB\-s \fInsocks\fR"
148 .IQ "\fB\-\-sockets \fInsocks\fR"
149 For \fBlatency\fR, sets the number of connections to initiate per
150 batch. For \fBrate\fR, sets the number of outstanding connections
151 attempts to maintain at any given time. The default is 100.
153 .IP "\fB\-b \fInbatches\fR"
154 .IQ "\fB\-\-batches \fInbatches\fR"
155 For \fBlatency\fR, sets the number of times to initiate and wait for
156 all of the connections to complete. The default is 1.
158 .IP "\fB\-c \fImaxrate\fR"
159 .IQ "\fB\-\-max\-rate \fImaxrate\fR"
160 For \fBrate\fR, caps the maximum rate at which connections will be
161 attempted to \fImaxrate\fR connections per second. By default there
164 .IP "\fB\-T \fImaxsecs\fR"
165 .IQ "\fB\-\-timeout \fImaxsecs\fR"
166 For \fBrate\fR, stops the benchmark after \fImaxsecs\fR seconds have
167 elapsed. By default, the benchmark continues until interrupted by a
172 \fBovs\-benchmark\fR uses standard POSIX socket calls for network
173 access, so it shares the strengths and limitations of TCP/IP and its
174 implementations in the local and remote TCP/IP stacks. Particularly,
175 TCP and its implementations limit the number of successfully completed
176 and then closed TCP connections. This means that \fBovs\-benchmark\fR
177 tests tend to slow down if run for long intervals or with large
178 numbers of sockets or batches, if the remote system is listening on
179 the port or ports being contacted. The problem does not occur when
180 the remote system is not listening. \fBovs\-benchmark\fR results are
181 therefore much more reliable and repeatable when the remote system is
182 not listening on the port or ports being contacted. Even a single
183 listening socket (e.g. range of ports 8000 to 9000 with one listener
184 on port 8080) can cause anomalies in results.
187 Be sure that the remote TCP/IP stack's firewall allows the benchmark's
188 traffic to be processed. For Open vSwitch benchmarking purposes, you
189 might want to disable the firewall with, e.g., \fBiptables \-F\fR.
192 \fBovs\-benchmark\fR is single-threaded. A multithreaded process
193 might be able to initiate connections more quickly.
196 A TCP connection consists of two flows (one in each direction), so
197 multiply the TCP connection statistics that \fBovs\-benchmark\fR
198 reports by 2 to get flow statistics.
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