1nbdkit-noparallel-filter(1) NBDKIT nbdkit-noparallel-filter(1)
2
6 nbdkit-noparallel-filter - nbdkit noparallel filter
7
9 nbdkit --filter=noparallel plugin [serialize=MODE] [plugin-args...]
10
12 "nbdkit-noparallel-filter" is a filter that intentionally disables
13 parallelism in handling requests from clients. It is mainly useful for
14 evaluating timing differences between various levels of parallelism.
15 It can also be used as a way to work around any bugs in a plugin's
16 claimed level of parallel support, without recompiling the plugin, or
17 to ease efforts when connecting with a client that can batch up several
18 requests but is not prepared to handle out-of-order replies.
19 To limit the number of concurrent clients it's usually better to use
21 nbdkit-limit-filter(1).
22
24 serialize=requests
25 serialize=all-requests
26 serialize=connections
27 Optional, controls how much serialization the filter will enforce.
28 Mode requests (default) prevents a single client from having more
29 than one in-flight request, but does not prevent parallel requests
30 from a second connection (if the plugin supports that). Mode all-
31 requests is stricter, enforcing that at most one request
32 (regardless of connection) will be active, but does not prevent
33 parallel connections (if the plugin supports that). Mode
34 connections is strictest, where there can be at most one client at
35 a time, and where the server will no longer advertise
36 "NBD_FLAG_MULTI_CONN" to clients.
37
39 Serve the file disk.img, but disallow out-of-order transaction
40 completion to a given client:
41 nbdkit --filter=noparallel file disk.img
43 Serve the file disk.img, but allowing only one client at a time:
45 nbdkit --filter=noparallel file serialize=connections disk.img
47
49 $filterdir/nbdkit-noparallel-filter.so
50 The filter.
51 Use "nbdkit --dump-config" to find the location of $filterdir.
53
55 "nbdkit-noparallel-filter" first appeared in nbdkit 1.14.
56
58 nbdkit(1), nbdkit-file-plugin(1), nbdkit-filter(3),
59 nbdkit-fua-filter(1), nbdkit-limit-filter(1), nbdkit-nocache-filter(1),
60 nbdkit-noextents-filter(1), nbdkit-nozero-filter(1).
61
63 Eric Blake
64
66 Copyright (C) 2018-2020 Red Hat Inc.
67
69 Redistribution and use in source and binary forms, with or without
70 modification, are permitted provided that the following conditions are
71 met:
72 · Redistributions of source code must retain the above copyright
74 notice, this list of conditions and the following disclaimer.
75 · Redistributions in binary form must reproduce the above copyright
77 notice, this list of conditions and the following disclaimer in the
78 documentation and/or other materials provided with the
79 distribution.
80 · Neither the name of Red Hat nor the names of its contributors may
82 be used to endorse or promote products derived from this software
83 without specific prior written permission.
84 THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
86 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
87 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
88 PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
89 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
90 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
91 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
92 BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
93 WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
94 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
95 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
96nbdkit-1.24.2 2021-03-02 nbdkit-noparallel-filter(1)