Root Over NFS Memory Problem

Root Over NFS Memory Problem

[Nick Couchman]

I'm trying to run a few clients using NFS for the root filesystem.  I'm
having a problem with what appears to be a memory "leak" (I'm not sure
it's actually a leak, but for all intents and purposes, it is).  What
happens is that I lose 8k of free memory every time I run a command. 
For example, if I repeatedly run the "free" command, the free memory
will drop 8k each time I run it.  If I instead run "free -s 1" (telling
free to update at 1 second intervals), it drops a couple of times and
then levels out.  The problem is bad enough that one of the clients ran
out of memory (swap - on a local hard drive - and physical RAM) the
other night and "kernel panicked".  The clients are running kernel
version 2.4.22 with the OpenMosix patch (2.4.22 seems to be the latest
"stable" OpenMosix version).  Has anyone run across this problem
before?  Any ideas what I can do to fix it?  Is it a known NFS bug in
2.4.22 that is fixed in later versions?  (I'm about to try another
version of the kernel which might give me an answer to that, but I
thought I'd ask).

Thanks in advance!
-- 
Nick Couchman <nick-lists@seakr.com>



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Re: Root Over NFS Memory Problem

[Bernd Schubert]

On Wednesday 03 March 2004 18:58, Nick Couchman wrote:
> I'm trying to run a few clients using NFS for the root filesystem.  I'm
> having a problem with what appears to be a memory "leak" (I'm not sure
> it's actually a leak, but for all intents and purposes, it is).  What
> happens is that I lose 8k of free memory every time I run a command.
> For example, if I repeatedly run the "free" command, the free memory
> will drop 8k each time I run it.  If I instead run "free -s 1" (telling
> free to update at 1 second intervals), it drops a couple of times and
> then levels out.  The problem is bad enough that one of the clients ran
> out of memory (swap - on a local hard drive - and physical RAM) the
> other night and "kernel panicked".  The clients are running kernel
> version 2.4.22 with the OpenMosix patch (2.4.22 seems to be the latest
> "stable" OpenMosix version).  Has anyone run across this problem
> before?  Any ideas what I can do to fix it?  Is it a known NFS bug in
> 2.4.22 that is fixed in later versions?  (I'm about to try another
> version of the kernel which might give me an answer to that, but I
> thought I'd ask).
>

We are running currently 43 system over a nfs root filesystem and none of 
those systems is suffering from such memory leak. So I really don't think 
this is a vanilla kernel issue. If you are sure that its the kernel, try 
without OpenMosix and other patches.

Cheers,
	Bernd


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Re: Root Over NFS Memory Problem

[Nick Couchman]

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> We are running currently 43 system over a nfs root filesystem and 
> none of those systems is suffering from such memory leak. So I 
> really don't think this is a vanilla kernel issue. If you are sure >
that its the kernel, try without OpenMosix and other patches.
>
> Cheers,
>        Bernd

Two things: 1) What version of the kernel are you running?  2) We have
another Linux box running the same kernel, but it is not booting
root-over-NFS, it is using the local hard drive.  This machine does not
"leak" memory.  Other ideas?  Could it be portmap?

--Nick
-- 
Nick Couchman
Information Technology
SEAKR Engineering, Inc.
Phone: (303) 790-8499
Fax: (303) 790-8720
Web: http://www.seakr.com

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Re: Root Over NFS Memory Problem

[Nick Couchman]

> Well, I don't thinkg that its important, we currently mount the 
> nfs-root directory from an initrd and not directly from the kernel >
nfs-root-mount functions. However until 2.4.20 we also used the 
> direct approach and had no problems. Sorry, no further ideas.
>
> Bernd

Looks like it has something to do with OpenMosix, so I'll take this
discussion to that forum.  Thanks!
-- 
Nick Couchman <nick-lists@seakr.com>



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