IOSTATS(4) IOSTATS(4)
NAME
iostats - file system to measure I/O
SYNOPSIS
iostats [ -d ] [ -C ] cmd [ args... ]
DESCRIPTION
Iostats is a user-level 9P filter that interposes itself
between a program and the regular file server, which allows
it to gather statistics of file system use at the level of
the Plan 9 file system protocol, 9P. After a program exits
a report is printed on standard error.
The report consists of three sections. The first section
reports the amount of user data in read and write messages
sent by the program and the average rate at which the data
was transferred. The protocol line reports the amount of
data sent as message headers, that is, protocol overhead.
The rpc line reports the total number of file system trans-
actions.
The second section gives the number of messages, the
fastest, slowest, and average turn around time and the
amount of data involved with each 9P message type. The
final section gives an I/O summary for each file used by the
program in terms of opens, reads and writes.
If the -d flag is present, a debugging log including all 9P
traffic is written to standard error.
The -C flag sets the MCACHE flag on the mount which allows
the kernel to cache (see bind(1)).
EXAMPLE
Display summary of file I/O incurred by ls(1):
iostats ls
Start a new shell, displaying all 9P traffic caused by the
shell or its children:
iostats -d rc
SOURCE
/sys/src/cmd/iostats.c
SEE ALSO
dup(3), exportfs(4)
BUGS
Page 1 Plan 9 (printed 12/21/24)
IOSTATS(4) IOSTATS(4)
Poor clock resolution means that large amounts of I/O must
be done to get accurate rate figures.
Can be fooled by programs that do fresh mounts outside its
purview, or by the use of names of files with content that
can vary by process (e.g., `#d', `/dev/cons').
Page 2 Plan 9 (printed 12/21/24)