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.IX Title "nbdkit-noparallel-filter 1"
.TH nbdkit-noparallel-filter 1 2024-05-10 nbdkit-1.38.2 NBDKIT
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH NAME
nbdkit\-noparallel\-filter \- nbdkit noparallel filter
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& nbdkit \-\-filter=noparallel plugin [serialize=MODE] [plugin\-args...]
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
\&\f(CW\*(C`nbdkit\-noparallel\-filter\*(C'\fR is a filter that intentionally disables
parallelism in handling requests from clients. It is mainly useful for
evaluating timing differences between various levels of parallelism.
It can also be used as a way to work around any bugs in a plugin's
claimed level of parallel support, without recompiling the plugin, or
to ease efforts when connecting with a client that can batch up
several requests but is not prepared to handle out-of-order replies.
.PP
To limit the number of concurrent clients it's usually better to use
\&\fBnbdkit\-limit\-filter\fR\|(1).
.SH PARAMETERS
.IX Header "PARAMETERS"
.IP \fBserialize=requests\fR 4
.IX Item "serialize=requests"
.PD 0
.IP \fBserialize=all\-requests\fR 4
.IX Item "serialize=all-requests"
.IP \fBserialize=connections\fR 4
.IX Item "serialize=connections"
.PD
Optional, controls how much serialization the filter will
enforce. Mode \fBrequests\fR (default) prevents a single client from
having more than one in-flight request, but does not prevent parallel
requests from a second connection (if the plugin supports that). Mode
\&\fBall-requests\fR is stricter, enforcing that at most one request
(regardless of connection) will be active, but does not prevent
parallel connections (if the plugin supports that). Mode
\&\fBconnections\fR is strictest, where there can be at most one client at
a time, and where the server will no longer advertise
\&\f(CW\*(C`NBD_FLAG_MULTI_CONN\*(C'\fR to clients.
.SH EXAMPLES
.IX Header "EXAMPLES"
Serve the file \fIdisk.img\fR, but disallow out-of-order transaction
completion to a given client:
.PP
.Vb 1
\& nbdkit \-\-filter=noparallel file disk.img
.Ve
.PP
Serve the file \fIdisk.img\fR, but allowing only one client at a time:
.PP
.Vb 1
\& nbdkit \-\-filter=noparallel file serialize=connections disk.img
.Ve
.SH FILES
.IX Header "FILES"
.ie n .IP \fR\fI$filterdir\fR\fI/nbdkit\-noparallel\-filter.so\fR 4
.el .IP \fR\f(CI$filterdir\fR\fI/nbdkit\-noparallel\-filter.so\fR 4
.IX Item "$filterdir/nbdkit-noparallel-filter.so"
The filter.
.Sp
Use \f(CW\*(C`nbdkit \-\-dump\-config\*(C'\fR to find the location of \f(CW$filterdir\fR.
.SH VERSION
.IX Header "VERSION"
\&\f(CW\*(C`nbdkit\-noparallel\-filter\*(C'\fR first appeared in nbdkit 1.14.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBnbdkit\fR\|(1),
\&\fBnbdkit\-file\-plugin\fR\|(1),
\&\fBnbdkit\-filter\fR\|(3),
\&\fBnbdkit\-fua\-filter\fR\|(1),
\&\fBnbdkit\-limit\-filter\fR\|(1),
\&\fBnbdkit\-multi\-conn\-filter\fR\|(1),
\&\fBnbdkit\-nocache\-filter\fR\|(1),
\&\fBnbdkit\-noextents\-filter\fR\|(1),
\&\fBnbdkit\-nozero\-filter\fR\|(1).
.SH AUTHORS
.IX Header "AUTHORS"
Eric Blake
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright Red Hat
.SH LICENSE
.IX Header "LICENSE"
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
.IP \(bu 4
Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
.IP \(bu 4
Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
.IP \(bu 4
Neither the name of Red Hat nor the names of its contributors may be
used to endorse or promote products derived from this software without
specific prior written permission.
.PP
THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.