nbdkit-stats-filter - display statistics about operations
nbdkit --filter=stats PLUGIN statsfile=FILE
[statsappend=true] [statsthreshold=PERCENTILE]nbdkit-stats-filter is a filter that displays statistics about NBD operations, such as the number of bytes read and written. Statistics are written to a file once when nbdkit exits.
# 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 totalThe file where we write the stats.
This parameter is required.
If set then we append to the file instead of replacing it.
If non-zero, track request size and alignment distribution and print histogram.
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.
Histogram output is truncated to PERCENTILE of requests. Default: 95.
The filter.
Use nbdkit --dump-config to find the location of $filterdir.
nbdkit-stats-filter first appeared in nbdkit 1.14.
nbdkit(1), nbdkit-filter(3), nbdkit-log-filter(1).
Richard W.M. Jones
Nikolaus Rath
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