[OpenAFS] Re: interpreting cmdebug output of locked entries

Andrew Deason adeason@sinenomine.net
Wed, 2 Nov 2011 22:16:29 -0500

On Wed, 2 Nov 2011 17:45:12 -0700
Jonathan Nilsson <jnilsson@uci.edu> wrote:

> > pid 3700 is actually probably just an afsd daemon. How long does it
> > stay like this?
> The system was wedged for a little over 12 hours until I noticed and
> rebooted it. But you are probably asking how long this particular
> cache entry was listed in the cmdebug output. I only ran cmdebug once,
> so I can't say...

Well actually, how long afs_xdcache was locked; or rather, how long the
output was identical to what you posted.

The cmdebug output you gave shows two things locked: the afs_xdcache
lock, and the lock for a cache entry. The first one is this:

Lock afs_xdcache status: (writer_waiting, write_locked(pid:3700 at:617), 1 waiters)

which is interesting because someone is waiting for the lock. If it
always says that we have it write locked at:617 for a long time, it may
not be the fault of AFS, since all we do in that lock location is a
small write to disk. The second one is this guy:

** Cache entry @ 0xea61a4c0 for 2.536870959.1.1 [ss2k.uci.edu]
    locks: (none_waiting, 1 read_locks(pid:22600))

Which is less interesting, because although it is locked, nobody is
waiting for the lock to be released.

Andrew Deason