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Oct 2014


A tool to monitor I/O latency in real time


ioping - simple disk I/O latency monitoring tool


-h | -v


This tool generates various I/O patterns and lets you monitor I/O speed and latency in real time.


-a, -warmup count
Ignore in statistics first count requests, default 1.
-c, -count count
Stop after count requests, default 0 (infinite).
-i, -interval time
Set time between requests, default 1s.
-l, -speed-limit size
Set speed limit in size per second. Increases interval to request-size / speed.
-r, -rate-limit count
Set rate limit in count per second. Increases interval to 1 / rate.
-t, -min-time time
Minimal valid request time (0us). Too fast requests are ignored in statistics.
-T, -max-time time
Maximum valid request time. Too slow requests are ignored in statistics.
-s, -size size
Request size, default 4k.
-S, -work-size size
Working set size (1m for directory, whole size for file or device).
-o, -work-offset size
Starting offset in the file/device (0).
-w, -work-time time
Stop after time passed, default 0 (infinite).
-p, -print-count count
Print raw statistics for every count requests (see format below).
-P, -print-interval time
Print raw statistics for every time.
-A, -async Use asynchronous I/O (io_setup(2), io_submit(2) etc syscalls).
-B, -batch Batch mode. Be quiet and print final statistics in raw format.
-C, -cached Use cached I/O. Suppress cache invalidation via posix_fadvise(2)) before read and fdatasync(2) after each write.
-D, -direct Use direct I/O (see O_DIRECT in open(2)).
-J, -json Print output in JSON format.
-L, -linear Use sequential operations rather than random. This also sets default request size to 256k (as in -size 256k).
-R, -rapid Disk seek rate test, or bandwidth test if used together with -linear.
This option suppress human-readable output for each request (as -quiet), sets default interval to zero (-interval 0), stops measurement after 3 seconds (-work-time 3) and increases default working set size to 64m (-work-size 64m). Working set (-work-size) should be increased accordingly if disk has huge hardware cache.
-W, -write Use writes rather than reads. Safe for temporary file in directory target. Write I/O gives more reliable results for systems where non-cached reads are not supported or cached at some level.
Might be *DANGEROUS* for file/device: it will shred your data. In this case should be repeated three times (-WWW).
-G, -read-write
Alternate read and write requests.
-Y, -sync Use sync I/O (see O_SYNC in open(2)).
-y, -dsync Use data sync I/O (see O_DSYNC in open(2)).
-k, -keep Keep and reuse temporary working file "ioping.tmp" (only for directory target).
-q, -quiet Suppress periodical human-readable output.
-h, -help Display help message and exit.
-v, -version
Display version and exit.

Argument suffixes

For options that expect time argument (-interval, -print-interval and -work-time), default is seconds, unless you specify one of the following suffixes (case-insensitive):
ns, nsec
nanoseconds (a billionth of a second, 1 / 1 000 000 000)
us, usec
microseconds (a millionth of a second, 1 / 1 000 000)
ms, msec
milliseconds (a thousandth of a second, 1 / 1 000)
s, sec seconds
m, min minutes
h, hour hours
For options that expect "size" argument (-size, -speed-limit, -work-size and -work-offset), default is bytes, unless you specify one of the following suffixes (case-insensitive):
sector disk sectors (a sector is always 512).
KiB, k, kb
kilobytes (1 024 bytes)
page memory pages (a page is always 4KiB).
MiB, m, mb
megabytes (1 048 576 bytes)
GiB, g, gb
gigabytes (1 073 741 824 bytes)
TiB, t, tb
terabytes (1 099 511 627 776 bytes)
For options that expect "number" argument (-count and -print-count) you can optionally specify one of the following suffixes (case-insensitive):
k kilo (thousands, 1 000)
m mega (millions, 1 000 000)
g giga (billions, 1 000 000 000)
t tera (trillions, 1 000 000 000 000)


Returns 0 upon success. The following error codes are defined:
1 Invalid usage (error in arguments).
2 Error during preparation stage.
3 Error during runtime.


ioping -print-count 100 -count 200 -interval 0 -quiet .
99 10970974 9024 36961531 90437 110818 358872 30756 100 12516420
100 9573265 10446 42785821 86849 95733 154609 10548 100 10649035
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
(1) count of requests in statistics
(2) running time (nanoseconds)
(3) requests per second (iops)
(4) transfer speed (bytes per second)
(5) minimal request time (nanoseconds)
(6) average request time (nanoseconds)
(7) maximum request time (nanoseconds)
(8) request time standard deviation (nanoseconds)
(9) total requests (including warmup, too slow or too fast)
(10) total running time (nanoseconds)


ioping .
Show disk I/O latency using the default values and the current directory, until interrupted. This command prepares temporary (unlinked/hidden) working file and reads random chunks from it using non-cached read requests.
ioping -c 10 -s 1M /tmp
Measure latency on /tmp using 10 requests of 1 megabyte each.
ioping -R /dev/sda
Measure disk seek rate.
ioping -RL /dev/sda
Measure disk sequential speed.
ioping -RLB . | awk ’{print $4}’
Get disk sequential speed in bytes per second.


This program was written by Konstantin Khlebnikov
Man-page was written by Kir Kolyshkin
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