用iopp查看每个进程的I/O数据

原贴:http://www.maycode.com/index.php/linux/34-linuxbase/1287-linux-fs.html

用iopp查看每个进程的I/O数据

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作者：管理员 2009-01-15 22:37

摘要：iopp是一个有效查看linux下每个进程I/O负载的工具。

If
you know me, you know I can’t pass up “I/O statistics per process.” No
way. So, after a moment of browsing the code, which is short and to the
point, I tried it out:

baron@kanga:~$ wget -q -O iopp.c "http://git.postgresql.org/?p=~markwkm/iopp.git;a=blob_plain;f=iopp.c;hb=HEAD"
baron@kanga:~$ gcc -o iopp iopp.c
baron@kanga:~$ ./iopp --help
usage: iopp -h|--help
usage: iopp [-ci] [-k|-m] [delay [count]]
-c, --command display full command line
-h, --help display help
-i, --idle hides idle processes
-k, --kilobytes display data in kilobytes
-m, --megabytes display data in megabytes

Sweet! Next,

baron@kanga:~$ ./iopp -i -k 5
pid    rchar    wchar    syscr    syscw      rkb      wkb     cwkb command
4912        2        1        0        0        0        0        0 dbus-daemon
5713        0        1        0        0        0        0        0 hald
5717       17        0        0        0        0        0        0 hald-runner
5932        0        2        0        0        0        0        0 NetworkManager
22101       94       28        0        0        0        0        0 Xorg
22238        4        4        0        0        0        0        0 pulseaudio
22684       29       55        1        0        0        0        0 firefox
26860        0       43        0        0        0        0        0 gnome-terminal

It behaves just like vmstat — it loops every 5 seconds until I stop it.

So what are we looking at here? I don’t see any documentation, but I
see from the source that it’s reading /proc/[PID]/io. Unfortunately
that’s not documented in my proc manpage, but there’s a patch that provides documentation for the file’s contents.

According to that, we’re looking at the pid, the number of kibibytes
read and written (even if they came from the cache), the number of read
and write system calls, and the number of kibibytes read and written to
physical medium (i.e. not just to the OS cache). Finally we have
canceled write kibibytes, and the command name. I won’t repeat the
documentation on the canceled write bytes — it is what it sounds like,
but there’s a little bit more explanation on that patch I linked.

This tool would have been very handy to know about last week. One of
my clients was seeing a lot of disk writes from a MySQL server, and it
would have made it considerably easier to diagnose the problem.

There is one small bug — the -i flag causes idle processes not to be
printed out, but it’s applied after bytes have been transformed into
kibi/mebibytes, so any process that has zeroes after that
transformation gets filtered out. So you’ll get different output from
-i -k than you will from -i or from -i -m. I’ll see if I can find the
author’s email address and let him know about this…