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To: freebsd-current@freebsd.org
cc: syssgm@dtir.qld.gov.au
Subject: Hang during NFS stress test
Date: Mon, 07 Apr 1997 16:46:37 +1000
From: Stephen McKay <syssgm@dtir.qld.gov.au>
Sender: owner-current@freebsd.org
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Setup: 386DX20 with 8Mb ram running 2.2.1 (or very close) continually
copying files from a 486DX33 running 2.1.7 back to the same mount point
via TCP NFS.  After two days (continuous copying) it has locked up.  It
still responds to pings, will switch virtual consoles, and I can get into
ddb, but nothing else.

Ddb shows that the machine is stuck in idle_loop(), and no processes are
on the run queue (whichqs == 0), but ps (ddb command) shows a number of
processes which are not waiting on anything.  For example, there are 3
getty's on the syscons virtual screens, and only one has non-zero wchan
(probably because I hit enter a few times on some screens to see if I
could wake them up).

The only unusual wchan is swapper waiting on swinuw (which must be from
pmap_swapin_proc).  Other processes are in nfsidl, pause, wait, ttyin, etc.

Any ideas what is going on?

I will keep the system up and hung in case anyone can think of any good
tests.  This system makes bad core dumps, so I can't save this stuff forever.

Stephen.