1nbdkit-rate-filter(1) NBDKIT nbdkit-rate-filter(1)
2
6 nbdkit-rate-filter - limit bandwidth by connection or server
7
9 nbdkit --filter=rate PLUGIN [PLUGIN-ARGS...]
10 [rate=BITSPERSEC]
11 [connection-rate=BITSPERSEC]
12 [rate-file=FILENAME]
13 [connection-rate-file=FILENAME]
14
16 "nbdkit-rate-filter" is a filter that limits the bandwidth that can be
17 used by the server. Limits can be applied per connection and/or for
18 the server as a whole.
19
21 nbdkit --filter=rate memory 64M rate=1M
22 Create a 64M RAM disk and limit server bandwidth as a whole to a
23 maximum of 1 Mbps (megabit per second).
24 nbdkit --filter=rate memory 64M connection-rate=50K
26 Limit each connection to 50 Kbps (kilobits per second). However as
27 there is no limit to the number of simultaneous connections this
28 does not limit overall server bandwidth.
29 nbdkit --filter=rate memory 64M connection-rate=50K rate=1M
31 Limit each connection to 50 Kbps. Additionally the total bandwidth
32 across all connections to the server is limited to 1 Mbps.
33 nbdkit --filter=rate memory 64M rate=1M rate-file=/tmp/rate
35 Initially limit bandwidth to 1 Mbps. While the server is running
36 the rate can be adjusted dynamically by writing a different rate
37 into /tmp/rate.
38
40 connection-rate=BITSPERSEC
41 Limit each connection to "BITSPERSEC".
42 rate=BITSPERSEC
44 Limit total bandwidth across all connections to "BITSPERSEC".
45 connection-rate-file=FILENAME
47 rate-file=FILENAME
48 Adjust the per-connection or total bandwidth dynamically by writing
49 "BITSPERSEC" into "FILENAME". See "DYNAMIC ADJUSTMENT" below.
50 "BITSPERSEC" can be specified as a simple number, or you can use a
52 number followed by "K", "M" etc to mean kilobits, megabits and so on.
53
55 Using the "connection-rate-file" or "rate-file" parameters you can
56 dynamically adjust the bandwidth while the server is running.
57 If the file is not present when the server starts up then the initial
59 rate is taken from the associated "connection-rate" or "rate" parameter
60 (or if that is not present, then it is unlimited). If the file is
61 deleted while the server is running then the last rate read from the
62 file continues to be used.
63 The file should be updated atomically (eg. create a new file, then
65 rename or mv(1) the new file over the old file).
66 There will be a short delay between the file being updated and the new
68 rate coming into effect.
69
71 You can specify "rate" and "connection-rate" on their own or together.
72 If you specify neither, the filter is turned off.
73 The rate filter approximates the bandwidth used by the NBD protocol on
75 the wire. Some operations such as zeroing and trimming are effectively
76 free (because only a tiny NBD message is sent over the network) and so
77 do not count against the bandwidth limit. NBD and TCP protocol
78 overhead is not included, so you may find that other tools such as
79 tc(8) and iptables(8) give more accurate results.
80 There are separate bandwidth limits for read and write (ie. download
82 and upload to the server).
83 If the size of requests made by your client is much larger than the
85 rate limit then you can see long, lumpy sleeps in this filter. In the
86 future we may modify the filter to break up large requests
87 automatically in order to limit the length of sleeps. Placing the
88 nbdkit-blocksize-filter(1) in front of this filter may help in the
89 meantime.
90
92 $filterdir/nbdkit-rate-filter.so
93 The filter.
94 Use "nbdkit --dump-config" to find the location of $filterdir.
96
98 "nbdkit-rate-filter" first appeared in nbdkit 1.12.
99
101 nbdkit(1), nbdkit-blocksize-filter(1), nbdkit-delay-filter(1),
102 nbdkit-filter(3), iptables(8), tc(8).
103
105 Richard W.M. Jones
106
108 Copyright (C) 2019 Red Hat Inc.
109
111 Redistribution and use in source and binary forms, with or without
112 modification, are permitted provided that the following conditions are
113 met:
114 · Redistributions of source code must retain the above copyright
116 notice, this list of conditions and the following disclaimer.
117 · Redistributions in binary form must reproduce the above copyright
119 notice, this list of conditions and the following disclaimer in the
120 documentation and/or other materials provided with the
121 distribution.
122 · Neither the name of Red Hat nor the names of its contributors may
124 be used to endorse or promote products derived from this software
125 without specific prior written permission.
126 THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
128 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
129 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
130 PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
131 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
132 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
133 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
134 BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
135 WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
136 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
137 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
138nbdkit-1.16.1 2019-12-03 nbdkit-rate-filter(1)