[alt.sources.wanted] Modifying a unix process table on the fly

dan@squid.rtech.com (Dan Dick "Squid Mugger") (01/12/91)

We have a process that is hung waiting for a device driver that will never
respond.  Therefore, that process cannot die--even with a kill -9 <PID>.
Does anybody have experience flipping the DISK-WAIT flag so the process can
think it is ok to die gracefully?

We are running Dynix 3.0 on a 10 processor Sequent Symmetry, but over-all, it
seems somewhat Berkeley-like in nature with some System V'ish characteristics
as well.  The adb program is not available, but dbx is.

Thanks in advance for any help you can give...If you wish to respond by mail,
my email address is dan@ingres.com or dan@ptolemy.arc.nasa.gov or
c2036@sn1033.cray.com--whichever is easiest.


	  Dan Dick

rbj@uunet.UU.NET (Root Boy Jim) (01/19/91)

In article <5962@rtech.Ingres.COM> dan@squid.ingres.com (Dan Dick "Squid Mgr") writes:
>We have a process that is hung waiting for a device driver that will never
>respond.  Therefore, that process cannot die--even with a kill -9 <PID>.
>Does anybody have experience flipping the DISK-WAIT flag so the process can
>think it is ok to die gracefully?

I have always thought that setting the "Wait Channel" to the address
of the lightning bolt (lbolt) would be a nice way to either
(1) unwedge a process, or (2) crash the system.
I would think it would depend on the particular type of hang involved.

I used to work with a guy who wrote a "user level sceduler" by
writing into the systems proc tables. This was for a government
procurement to make the benchmarking suites run faster. We were
supposed to tune their kernel and we couldn't get them to put the
stuff in their kernel, so it had to be done as a user process.

-- 

	Root Boy Jim Cottrell <rbj@uunet.uu.net>
	Close the gap of the dark year in between