[Beowulf] cli alternative to cluster top?

Robert G. Brown rgb at phy.duke.edu
Mon Dec 1 15:33:40 PST 2008

On Mon, 1 Dec 2008, Thomas Vixel wrote:

> The main requirements were that 1) "it must look like top", 2) it must
> be cli-based, 3) it should not introduce another piece of (server)
> software (and thus point of failure) into the system, 4) and it should
> not require any local hacks on our part.
> Since this is a web cluster, I suppose the most logical transport
> would be HTTP, but everything I've seen so far would require me to
> violate (4) to satisfy 1-3. SSH & SNMP are also available, I could see
> SNMP being problematic for a project like this. SSH *might* work and
> *might* be scalable for a project like this since the main expense is
> in the construction the connections (and they can be re-used across
> the course of the execution), but I have yet to find a top-like
> program that leverages it.
> xmlsysd & wulfstat would appear to be the least expensive solution to
> this problem, but as I said, management already nixed it.

Um, I don't know what you call a "local hack", but it IS called xmlsysd
for a reason.  You don't have to run it as an actual public daemon.  It
produces xml, and in inetd mode it reads from stdin and writes to
stdout.  Try this.  Install xmlsysd on something.  Then in the command
line, enter:

  ./xmlsysd -i 7880

(the port number isn't important -- you're just telling it to use inetd
mode).  It will run and nothing will happen.  Then WITHOUT BREAKING OUT
just enter


See?  I'd think you could write a TRIVIAL PHP or perl wrapper and pop
this out through a webserver.

The other end is a bit trickier, but I think doable.
wulfstat/wulflogger don't currently speak GET, but the parser should
still work.  If you only wanted a few objects (e.g. load average), you
could again write a pretty trivial perl script to get them.  Or if you
don't need it today (or the next week or two) over break I could
probably hack wulfstat OR wulflogger to connect to a web interface and
just use GET to get an update, and maybe write a "permanent" CGI wrapper
that puts xmlsysd output on a web address when called (in lieu of


> Honestly, if it weren't for (4), I'd probably just grab the top source
> and graft it onto a SSH library. It might not be the most efficient
> solution, but for a HA cluster it doesn't necessarily HAVE to be.

I'd think the solution above would be a lot easier.

> On 11/30/08, Robert G. Brown <rgb at phy.duke.edu> wrote:
>> On Sat, 29 Nov 2008, Greg Kurtzer wrote:
>>> Warewulf has a real time top like command for the cluster nodes and
>>> has been known to scale up to the thousands of nodes:
>>> http://www.runlevelzero.net/images/wwtop-screenshot.png
>>> We are just kicking off Warewulf development again now that Perceus
>>> has gotten to a critical mass and Caos NSA 1.0 has been released. We
>>> should have our repositories for Warewulf-3 pre-releases up shortly
>>> but if you need something ASAP, please contact me offline and I will
>>> get you what you need.
>>> Thanks!
>>> Greg
>>> On Wed, Nov 26, 2008 at 12:39 PM, Thomas Vixel <tvixel at gmail.com> wrote:
>>>> I've been googling for a top-like cli tool to use on our cluster, but
>>>> the closest thing that comes up is Rocks' "cluster top" script. That
>>>> could be tweaked to work via the cli, but due to factors beyond my
>>>> control (management) all functionality has to come from a pre-fab
>>>> program rather than a software stack with local, custom modifications.
>>>> I'm sure this has come up more than once in the HPC sector as well --
>>>> could anyone point me to any top-like apps for our cluster?
>>>> For reference, wulfware/wulfstat was nixed as well because of the
>>>> xmlsysd dependency.
>> That's fine, but I'm curious.  How do you expect to run a cluster
>> information tool over a network without a socket at both ends?  If not
>> xmlsysd, then something else -- sshd, xinetd, dedicated or general
>> purpose, where the latter almost certainly will have have higher
>> overhead?  Or are you looking for something with a kernel level network
>> interface, more like scyld?
>>    rgb
>>>> _______________________________________________
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>>> --
>>> Greg Kurtzer
>>> http://www.infiscale.com/
>>> http://www.runlevelzero.net/
>>> http://www.perceus.org/
>>> http://www.caoslinux.org/
>>> _______________________________________________
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>> Robert G. Brown                            Phone(cell): 1-919-280-8443
>> Duke University Physics Dept, Box 90305
>> Durham, N.C. 27708-0305
>> Web: http://www.phy.duke.edu/~rgb
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Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu

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