disk wait mystery

[Oliver Fromme]

Brett Wynkoop wrote:
 > > > 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]
 > [...]
 > 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.

That's normal (on all architectures, not just arm).  Those
"processes" in square brackets are kernel threads which are
uninterruptible (well, for some definition of uninterruptible).
So they always have the "D" flag set, even if they don't wait
for the disk.

Best regards
   Oliver


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