[Beowulf] Re: MOSIX2

Tony Travis ajt at rri.sari.ac.uk
Thu Oct 2 02:25:33 PDT 2008

Vincent Diepeveen wrote:
> [...]
> Supporting a thing like openmosix requires a lot more than 1 guy who in 
> order to modify 3 bytes needs 1000 dollar.

Hello, Vincent.

I've been involved in the openMosix project from the start, and I still 
use it. My comment about the $1,000 for 'updates' concerned the cost an 
'academic' update and support subscription to MOSIX2, which has nothing 
to do with openMosix. I think that is quite a reasonable cost, actually, 
and I dodn't criticise people who want to pay for support. It's not the 
cost that bothers me most, but the restrictions of the MOSIX2 licence.

> [...]
> In itself it would be GREAT if there is 1 open source project there, as 
> that joins forces more. My hope is that open-ssi
> will work great for highend nic's also and slowly get to a phase that 
> all features work great.

OK, maybe I should have another look at the most recent OpenSSI...

> OpenMosix nor openssi could migrate processes that work with shared 
> memory, a nerd feature i like personally a lot.

Actually there is a version of openMosix that can migrate programs using 
shared memory. Unfortunately, when I tried it, processes would migrate 
away from the 'home' node but wouldn't migrate back! This is a problem 
for openMosix, because processes have to migrate back to the 'home' node 
to make system calls. One of my (small) contributions to openMosix was 
to patch it to avoid migrations just to read the time. This is slightly 
relevant to another thread on the Beowulf list, because reading the time 
locally on a node to avoid the process migration overhead requires that 
the nodes all run NTP otherwise you get problems with clock skew...

> Just claiming that they use 'stolen' features like page migration is 
> like claiming that linux stole multithreading from unix;
> it is a bad attempt to smear dirt just to earn a 1000 dollar.
> It is not a reason to not use it. It is a bad attempt to spit at these 
> guys who donate time and their money without asking for payment.

Sadly, there was a lot of bad feeling between the openMosix and OpenSSI 
communities and I should not have tried to make light of it. In fact it 
is a compliment to openMosix that the load-balancer algorithm was used 
in OpenSSI, not an insult, and BTW I'm one of those guys who donated 
their time without asking for payment.

I did put a wry smile after my comment ;-)

Dr. A.J.Travis, University of Aberdeen, Rowett Institute of Nutrition
and Health, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, Scotland, UK
tel +44(0)1224 712751, fax +44(0)1224 716687, http://www.rowett.ac.uk
mailto:ajt at rri.sari.ac.uk, http://bioinformatics.rri.sari.ac.uk/~ajt

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