io - Summarize I/O resources used by the command

This is I/O version of time command and outputs I/O resources used by the command.

Requirements

procfs - Linux, etc.

The measurement results are read from the /proc/<PID>/io.

Usage

# $ base64 -w 999 /dev/urandom | head -n 10000 > data.txt
# $ wc data.txt
#    10000    10000 10000000 data.txt

$ export IOCLEANUP='sudo sh -c "echo 1 > /proc/sys/vm/drop_caches"'
$ export IOWARMUP='sort --version'

$ io sort data.txt > /dev/null
io: cleanup: sudo sh -c "echo 1 > /proc/sys/vm/drop_caches"
io: warmup: sort --version

rchar: 10005365
wchar: 10000000
syscr: 124
syscw: 2442
read_bytes: 10002432
write_bytes: 0
cancelled_write_bytes: 0

Note: See also env time -v <COMMAND> (GNU time).

Environment variables

IOCLEANUP

Specifies cleanup commands to be executed before measurement is performed. Typically, it specifies a command to clear the cache.

IOWARMUP

Specifies the command to be executed before measurement. This is used to preload the command to be executed, etc., into memory in advance.

Useless Use of Cat

See https://en.wikipedia.org/wiki/Cat_(Unix)#Useless_use_of_cat

$ base64 -w 999 /dev/urandom | head -n 1000000 > data.txt

$ export IOCLEANUP='sudo sh -c "echo 1 > /proc/sys/vm/drop_caches"'
$ export IOWARMUP='bash /dev/null; sort --version; cat --version'

$ io bash -c 'time sort data.txt > /tmp/output.txt'
io: cleanup: sudo sh -c "echo 1 > /proc/sys/vm/drop_caches"
io: warmup: bash /dev/null; sort --version; cat --version

real    0m4.269s
user    0m3.270s
sys     0m1.699s

rchar: 1000014824
wchar: 1000000043
syscr: 149
syscw: 244146
read_bytes: 1000058880
write_bytes: 1000001536
cancelled_write_bytes: 0

$ io bash -c 'time cat data.txt | sort > /tmp/output.txt'
io: cleanup: sudo sh -c "echo 1 > /proc/sys/vm/drop_caches"
io: warmup: bash /dev/null; sort --version; cat --version

real    0m8.061s
user    0m2.720s
sys     0m4.083s

rchar: 3959315116
wchar: 3959296043
syscr: 548720
syscw: 730159
read_bytes: 1000214528
write_bytes: 2959458304
cancelled_write_bytes: 1959456768

Comparison with GNU time

$ base64 -w 999 /dev/urandom | head -n 1000000 > data.txt

$ sudo sh -c "echo 1 > /proc/sys/vm/drop_caches"
$ env time -v bash -c 'sort data.txt > /tmp/output.txt'
        Command being timed: "bash -c sort data.txt > /tmp/output.txt"
        User time (seconds): 3.12
        System time (seconds): 1.83
        Percent of CPU this job got: 115%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:04.30
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 1104064
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 5
        Minor (reclaiming a frame) page faults: 275750
        Voluntary context switches: 3036
        Involuntary context switches: 38
        Swaps: 0
        File system inputs: 1953720
        File system outputs: 1953128
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

$ sudo sh -c "echo 1 > /proc/sys/vm/drop_caches"
$ env time -v bash -c 'cat data.txt | sort > /tmp/output.txt'
        Command being timed: "bash -c cat data.txt | sort > /tmp/output.txt"
        User time (seconds): 2.83
        System time (seconds): 4.15
        Percent of CPU this job got: 85%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:08.15
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 17704
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 6
        Minor (reclaiming a frame) page faults: 5402
        Voluntary context switches: 39994
        Involuntary context switches: 36
        Swaps: 0
        File system inputs: 1953888
        File system outputs: 5780192
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0