"df" command prone to hanging

David C. Niemi (niemidc@clark.net)
Tue, 24 Oct 1995 14:54:48 -0400 (EDT)

I have noticed over the past few runins I have had with hung device
drivers that the "df" command tends to get hung up in disk wait, even when
df is run on file systems which are not having a problem.

I also notice that if a floppy read is in progress (e.g. cp /dev/fd0
/dev/null) any df's during that time tend to have to wait until the floppy
read finishes. However, other types of disk accesses (this is on an EISA
based IDE disk) do not seem have to wait. Both processes are listed as
being in the dreaded "D" state.

What is special about "df", and could it be made vulnerable to hanging up
or waiting around by some sort of kernel change?

---David C. Niemi---niemidc@clark.net----703-904-3596---Reston, VA USA---
There is no match for the fervor of a new initiate, the confidence of the
unquestioning, or the appeal of oversimplified answers to complex issues.