Re: top displaying 50% si time and 50% idle on idle machine

["Metathronius Galabant" <m.galabant@googlemail.com>]

> > Kernel 2.6.17.11 with tg3 network driver, NAPI enabled (Distro CentOS 4.4).
> > top shows strangely 50% idle even if the machine is _completely_ idle.
> >
> > top - 01:04:30 up 4 days, 12:05,  2 users,  load average: 0.00, 0.00, 0.00
> > Tasks:  34 total,   2 running,  32 sleeping,   0 stopped,   0 zombie
> > Cpu(s):  0.0% us,  0.0% sy,  0.0% ni, 50.0% id,  0.0% wa,  0.0% hi, 50.0%si

> Do `ps aux', look for a process stuck in D state.

The issue that startled me: there is _NO_ process in a D state!
BTW what means si? (interrupt service time? google didn't find anything)

ps auxwm output following:

USER       PID %CPU %MEM   VSZ  RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.0  1692  572 ?        -    Sep04   0:00 init [3]

root         -  0.0    -     -    - -        Ss   Sep04   0:00 -
root         2  0.0  0.0     0    0 ?        -    Sep04   0:00 [ksoftirqd/0]
root         -  0.0    -     -    - -        SN   Sep04   0:00 -
root         3  0.0  0.0     0    0 ?        -    Sep04   0:00 [events/0]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root         4  0.0  0.0     0    0 ?        -    Sep04   0:00 [khelper]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root         5  0.0  0.0     0    0 ?        -    Sep04   0:00 [kthread]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root         7  0.0  0.0     0    0 ?        -    Sep04   0:00 [kblockd/0]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root         8  0.0  0.0     0    0 ?        -    Sep04   0:00 [kseriod]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root        70  0.0  0.0     0    0 ?        -    Sep04   0:00 [pdflush]
root         -  0.0    -     -    - -        S    Sep04   0:00 -
root        71  0.0  0.0     0    0 ?        -    Sep04   0:00 [pdflush]
root         -  0.0    -     -    - -        S    Sep04   0:00 -
root        72  0.0  0.0     0    0 ?        -    Sep04   0:00 [kswapd0]
root         -  0.0    -     -    - -        S    Sep04   0:00 -
root        73  0.0  0.0     0    0 ?        -    Sep04   0:00 [aio/0]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root       672  0.0  0.0     0    0 ?        -    Sep04   0:00 [kpsmoused]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root       685  0.0  0.0     0    0 ?        -    Sep04   0:00 [kjournald]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root      1666  0.0  0.0  1588  464 ?        -    Sep04   0:00 udevd
root         -  0.0    -     -    - -        S<s  Sep04   0:00 -
root      2065  0.0  0.0     0    0 ?        -    Sep04   0:00 [kjournald]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root      2073  0.0  0.0     0    0 ?        -    Sep04   0:00 [kjournald]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root      2763  0.0  0.0  2484  928 ?        -    Sep04   0:00 crond
root         -  0.0    -     -    - -        Ss   Sep04   0:00 -
root      2779  0.0  0.0  1532  408 tty2     -    Sep04   0:00
/sbin/mingetty tty2
root         -  0.0    -     -    - -        Ss+  Sep04   0:00 -
root      2780  0.0  0.0  1536  416 tty3     -    Sep04   0:00
/sbin/mingetty tty3
root         -  0.0    -     -    - -        Ss+  Sep04   0:00 -
root      4495  0.0  0.0  2904 1236 ?        -    Sep04   0:00 login -- root
root         -  0.0    -     -    - -        Ss   Sep04   0:00 -
root      6582  0.0  0.0     0    0 ?        -    Sep04   0:00 [reiserfs/0]
root         -  0.0    -     -    - -        S<   Sep04   0:00 -
root      7406  0.0  0.0  2344 1380 tty1     -    Sep06   0:00 -bash
root         -  0.0    -     -    - -        Ss+  Sep06   0:00 -
root      8158  0.0  0.0  4076 1132 ?        -    Sep06   0:01 /usr/sbin/sshd
root         -  0.0    -     -    - -        Ss   Sep06   0:01 -
root     10342  0.0  0.0  2244  608 ?        -    Sep08   0:03 syslogd -m 0
root         -  0.0    -     -    - -        Ss   Sep08   0:03 -
root     10347  0.0  0.0  1672  384 ?        -    Sep08   0:00 klogd -x
root         -  0.0    -     -    - -        Ss   Sep08   0:00 -
root     16078  0.0  0.0  8040 2240 ?        -    Sep10   0:00 sshd: root@pts/0
root         -  0.0    -     -    - -        Ss   Sep10   0:00 -
root     16089  0.0  0.0  2516 1256 pts/0    -    Sep10   0:00 -bash
root         -  0.0    -     -    - -        Ss   Sep10   0:00 -
nscd     24962  0.0  0.0 106476 840 ?        -    03:43   0:00 /usr/sbin/nscd
nscd         -  0.0    -     -    - -        Ssl  03:43   0:00 -
nscd         -  0.0    -     -    - -        Ssl  03:43   0:00 -
nscd         -  0.0    -     -    - -        Ssl  03:43   0:00 -
nscd         -  0.0    -     -    - -        Ssl  03:43   0:00 -
nscd         -  0.0    -     -    - -        Ssl  03:43   0:00 -
nscd         -  0.0    -     -    - -        Ssl  03:43   0:00 -
nscd         -  0.0    -     -    - -        Ssl  03:43   0:00 -
root     24972  0.0  0.0  2548  724 pts/0    -    03:44   0:00 ps auxwm
root         -  0.0    -     -    - -        R+   03:44   0:00 -

>         echo t > /proc/sysrq-trigger
>         dmesg -s 1000000 > foo
>
> then edit foo, search for the process in D state (look for " D ") and send
> that process's backtrace record.

This does only make sense if I have found the offender? I tried it,
nothing unusual and almost no output.

Is there any way to track it down? Just hints in the right direction
are highly appreciated!
Thanks,
M.
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