[787] in linux-net channel archive
Re: Strange behaviour with NFS
daemon@ATHENA.MIT.EDU (Rob Janssen reading Linux mailingl)
Sat Jul 29 12:57:39 1995
From: linux@pe1chl.ampr.org (Rob Janssen reading Linux mailinglist)
To: becker@cesdis1.gsfc.nasa.gov (Donald Becker)
Date: Wed, 26 Jul 1995 23:25:58 +0200 (MET DST)
Cc: linux-net@vger.rutgers.edu
In-Reply-To: <9507260415.AA10825@cesdis.gsfc.nasa.gov> from "Donald Becker" at Jul 26, 95 00:15:09 am
Reply-To: linux-vger@wab-tis.rabobank.nl
According to Donald Becker:
> >Whenever the nfs server isn't reachable the process on the client
> >machine just hangs around, partially in 'D' status which means
> >non-interruptable.
>
> I also encountered this problem today. This bug hung a few nodes on our
> Linux cluster. Luckily one still had a few process slots left to figure to
> do a 'ps'. Here a few notes:
> 1. The processes were in the 'D' disk-wait state. Most were
> swapped out.
This is (unfortunately) similar to what happens after a disk read error
on a local drive. Processes are in 'D' state after a failed filesystem
access.
> 2. The processes counted toward the load average, but didn't consume
> CPU time. The load average on the still-working machine was >35.
This is why I always apply the following patch:
*** linux/kernel/sched.c~ Fri Dec 10 00:38:26 1993
--- linux/kernel/sched.c Fri Dec 10 01:10:50 1993
***************
*** 441,447 ****
for(p = &LAST_TASK; p > &FIRST_TASK; --p)
if (*p && ((*p)->state == TASK_RUNNING ||
- (*p)->state == TASK_UNINTERRUPTIBLE ||
(*p)->state == TASK_SWAPPING))
nr += FIXED_1;
return nr;
--- 441,446 ----
Unfortunately, Linus does not accept it into the standard kernel.
I think a sleeping process should not count towards the CPU load average.
> 3. Doing 'kill -1' and 'kill -9' had no effect. The processes
> didn't even turn into zombies.
Yes, that is really unfortunate. It causes the system shutdown to
fail (disks cannot be unmounted because they are busy) and a reboot
will require fsck's to run.
Rob
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