3 iostats \- file system to measure I/O
17 is a user-level 9P filter that interposes itself between a program
18 and the regular file server, which
19 allows it to gather statistics of file system
20 use at the level of the Plan 9 file system protocol, 9P.
22 exits a report is printed on standard error.
24 The report consists of three sections.
25 The first section reports the amount
30 messages sent by the program and the average rate at
31 which the data was transferred.
34 line reports the amount
35 of data sent as message headers, that is,
40 total number of file system transactions.
42 The second section gives
43 the number of messages, the fastest, slowest, and average turn around
44 time and the amount of data involved with each 9P
46 The final section gives an I/O summary for each file used
47 by the program in terms of opens, reads and writes.
51 flag is present, a debugging log including all 9P traffic
52 is written to standard error.
56 flag sets the MCACHE flag on the mount which allows
57 the kernel to cache (see
60 Display summary of file I/O incurred by
67 Start a new shell, displaying all 9P traffic caused by the shell or its children:
73 .B /sys/src/cmd/iostats.c
78 Poor clock resolution means that large amounts of I/O must be done to
79 get accurate rate figures.
81 Can be fooled by programs that do fresh mounts outside its purview,
82 or by the use of names of files with content that can vary by process (e.g.,