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.\" ========================================================================
.\"
.IX Title "nbdkit-stats-filter 1"
.TH nbdkit-stats-filter 1 "2023-01-04" "nbdkit-1.32.5" "NBDKIT"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
nbdkit\-stats\-filter \- display statistics about operations
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\& nbdkit \-\-filter=stats PLUGIN statsfile=FILE
\&                       [statsappend=true] [statsthreshold=PERCENTILE]
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\f(CW\*(C`nbdkit\-stats\-filter\*(C'\fR is a filter that displays statistics about \s-1NBD\s0
operations, such as the number of bytes read and written.  Statistics
are written to a file once when nbdkit exits.
.SH "EXAMPLE OUTPUT"
.IX Header "EXAMPLE OUTPUT"
.Vb 10
\& # nbdkit \-\-filter=exitlast \-\-filter=stats memory 25G statsfile=example.txt
\& # nbd\-client localhost /dev/nbd1 && mkfs.ext4 /dev/nbd1 && sync &&
\&   nbd\-client \-d /dev/nbd1
\& [....]
\& # cat example.txt
\& total: 191 ops, 21.917545 s, 25.13 GiB, 1.15 GiB/s
\& read: 136 ops, 0.000230 s, 3.16 MiB, 13.43 GiB/s op, 147.83 KiB/s total
\&   Request size and alignment breakdown:
\&     12 bits: 68.4% (93 reqs, 372.00 KiB total)
\&          12 bit aligned: 100.0% (93)
\&          13 bit aligned:  72.0% (67)
\&          14 bit aligned:  55.9% (52)
\&          15 bit aligned:  48.4% (45)
\&          16 bit aligned:  43.0% (40)
\&     14 bits: 10.3% (14 reqs, 296.00 KiB total)
\&          12 bit aligned: 100.0% (14)
\&          13 bit aligned:  35.7% (5)
\&          19 bit aligned:  21.4% (3)
\& [....]
\&     other sizes:  3.7% (5 reqs, 3.16 MiB total)
\&
\& write: 36 ops, 0.125460 s, 132.38 MiB, 1.03 GiB/s op, 6.04 MiB/s total
\&   Request size and alignment breakdown:
\&     12 bits: 50.0% (18 reqs, 72.00 KiB total)
\&          12 bit aligned: 100.0% (18)
\&          13 bit aligned:  77.8% (14)
\&          27 bit aligned:  72.2% (13)
\&          31 bit aligned:  66.7% (12)
\&          32 bit aligned:  33.3% (6)
\&          33 bit aligned:  22.2% (4)
\&          34 bit aligned:  11.1% (2)
\&     14 bits: 30.6% (11 reqs, 224.00 KiB total)
\&          12 bit aligned: 100.0% (11)
\&          27 bit aligned:  90.9% (10)
\&     25 bits: 11.1% (4 reqs, 128.00 MiB total)
\&          25 bit aligned: 100.0% (4)
\&          26 bit aligned:  50.0% (2)
\&          27 bit aligned:  25.0% (1)
\&     16 bits:  2.8% (1 reqs, 64.00 KiB total)
\&          16 bit aligned: 100.0% (1)
\&
\& trim: 14 ops, 0.002687 s, 25.00 GiB, 9304.06 GiB/s op, 1.14 GiB/s total
\&   Request size and alignment breakdown:
\&     31 bits: 85.7% (12 reqs, 24.00 GiB total)
\&          24 bit aligned: 100.0% (12)
\&     24 bits:  7.1% (1 reqs, 16.00 MiB total)
\&
\& flush: 5 ops, 0.000002 s, 0 bytes, 0 bytes/s op, 0 bytes/s total
.Ve
.SH "PARAMETERS"
.IX Header "PARAMETERS"
.IP "\fBstatsfile=\fR\s-1FILE\s0" 4
.IX Item "statsfile=FILE"
The file where we write the stats.
.Sp
This parameter is required.
.IP "\fBstatsappend=true\fR" 4
.IX Item "statsappend=true"
If set then we append to the file instead of replacing it.
.IP "\fBstatsthreshold=\fR\s-1PERCENTILE\s0" 4
.IX Item "statsthreshold=PERCENTILE"
If non-zero, track request size and alignment distribution and print
histogram.
.Sp
Requests are grouped by the number of bits that are needed to represent
the request size (e.g. a request of size 3892 needs will be grouped
with all requests of size 2^11=2048 to 2^12\-1=4095), and the number of
trailing zero bits in the offset.
.Sp
Histogram output is truncated to \s-1PERCENTILE\s0 of requests. Default: 95.
.SH "FILES"
.IX Header "FILES"
.IP "\fI\f(CI$filterdir\fI/nbdkit\-stats\-filter.so\fR" 4
.IX Item "$filterdir/nbdkit-stats-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\-stats\-filter\*(C'\fR first appeared in nbdkit 1.14.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBnbdkit\fR\|(1),
\&\fBnbdkit\-filter\fR\|(3),
\&\fBnbdkit\-log\-filter\fR\|(1).
.SH "AUTHORS"
.IX Header "AUTHORS"
Richard W.M. Jones
.PP
Nikolaus Rath
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright (C) 2019\-2022 Red Hat Inc.
.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
\&\s-1THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS\s0 ''\s-1AS IS\s0'' \s-1AND
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\s0 (\s-1INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES\s0; \s-1LOSS OF
USE, DATA, OR PROFITS\s0; \s-1OR BUSINESS INTERRUPTION\s0) \s-1HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT\s0 (\s-1INCLUDING NEGLIGENCE OR OTHERWISE\s0) \s-1ARISING IN ANY WAY OUT
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.\s0