disk wait mystery

[Ronald Klop]

On Wed, 30 Jan 2013 11:52:36 +0100, Erich Dollansky  
<erichsfreebsdlist at alogt.com> wrote:

> Hi,
>
> On Wed, 30 Jan 2013 05:37:29 -0500
> Brett Wynkoop <wynkoop at wynn.com> wrote:
>
>> On Wed, 30 Jan 2013 10:39:37 +0100
>> "Ronald Klop" <ronald-freebsd8 at klop.yi.org> wrote:
>>
>> > On Wed, 30 Jan 2013 06:18:49 +0100, Brett Wynkoop <wynkoop at wynn.com>
>> > wrote:
>> >
>> > > Greeting-
>> > >
>> > > Can anyone figure out why a mainly idle bone with only 2 user
>> > > shells via ssh running would have so much in disk wait?
>> > >
>> > > wynkoop at beaglebone:~ % !ps
>> > > ps ax
>> > > PID TT  STAT     TIME COMMAND
>> > >   0  -  DLs   0:00.02 [kernel]
>> > >   1  -  ILs   0:00.20 /sbin/init --
>> > >   2  -  DL    0:00.00 [xpt_thrd]
>> > >   3  -  DL    0:01.92 [task: mmc/sd card]
>> > >   4  -  DL    0:00.01 [pagedaemon]
>> > >   5  -  DL    0:00.00 [vmdaemon]
>> > >   6  -  DL    0:00.00 [pagezero]
>> > >   7  -  DL    0:00.02 [bufdaemon]
>> > >   8  -  DL    0:00.02 [vnlru]
>> > >   9  -  DL    0:00.10 [syncer]
>> > >  10  -  RL   17:15.90 [idle]
>> > >  11  -  WL    0:07.91 [intr]
>> > >  12  -  DL    0:00.17 [geom]
>> > >  13  -  DL    0:00.21 [yarrow]
>> > >  14  -  DL    0:00.06 [softdepflush]
>> > >  15  -  DL    0:00.15 [schedcpu]
>> > > 106  -  DL    0:00.00 [md0]
>> > > 410  -  Is    0:00.06 dhclient: cpsw0 [priv] (dhclient)
>> > > 448  -  Is    0:00.07 dhclient: cpsw0 (dhclient)
>> > > 449  -  Is    0:00.01 /sbin/devd
>> > > 634  -  Is    0:00.04 /usr/sbin/sshd
>> > > 638  -  Is    0:00.55 /usr/sbin/cron -s
>> > > 682  -  Is    0:00.64 sshd: wynkoop [priv] (sshd)
>> > > 685  -  S     0:00.29 sshd: wynkoop at pts/0 (sshd)
>> > > 678 u0  Is+   0:00.19 /usr/libexec/getty std.9600 ttyu0
>> > > 686  0  Ss    0:00.74 -csh (csh)
>> > > 831  0  R+    0:00.16 ps ax
>> > > wynkoop at beaglebone:~ %
>> > >
>> > > -Brett
>> > >
>> >
>> > Hi,
>> >
>> > Maybe I missed a previous email, but you don't provide much
>> > information for people to think about.
>> > As a start you might show the 'disk wait' output.
>> >
>> > Ronald.
>> >
>>
>> Ronald-
>>
>> From the ps man page:
>>               D       Marks a process in disk (or other short term,
>>               uninterruptible) wait.
>>
>>
>> Note all the D entries in the above ps output.
>>
> how I understand the system, I would say that these tasks are all
> swapped out to disk.
>
> Erich

 From the ps man page:
  If the arguments cannot be
      located (usually because it has not been set, as is the case of system
      processes and/or kernel threads) the command name is printed within
      square brackets.

These are system processes. Would not be very nice to have for example the  
pagedaemon swapped out.

Ronald.