[Wylug-help] D uninterruptible sleep (usually IO) WAS: NFS woes

[Dave Fisher]

On Wed, Jul 14, 2004 at 10:53:33PM +0100, Roger Leigh wrote:
> Dave Fisher <davef at gbdirect.co.uk> writes:
>
> >  ... mmm ... still no solution, but one intriguing bit of diagnostic
> > info.
> >
> > ps reports:
> >
> > nfsuser       658  0.0  0.2  1936  796 ?        D    19:13   0:04 /usr/sbin/rpc.nfsd
> >
> > indicating that it is in "D uninterruptible sleep"
>
> Are you dropping incoming UDP packets?

Looks like it:

$ netstat -s -u
Udp:
    7103 packets received
    55 packets to unknown port received.
    723 packet receive errors
    6773 packets sent


> > ... so, unfortunately are several dvd writing processes like growisofs
> > and mkisofs (thereby preventing all access to the dvd writer).
> >
> > Is there any reasonable way of waking the damn things up and killing
> > them off?
>
> No.  They are stuck on a kernel wait queue and won't run again until
> whatever system call they are stuck in has completed.  Until then, you
> can't send any signals, including SIGKILL.
>
> If you try some ps options, you'll be able to see exactly which call
> it's stuck in, which might be helpful.

Suggestions?

The ps man page is not the worst, but it does suffer from the classic 'I'm not going to tell you what any of these codes mean, you should know them already' problem.

Dave