Network RAM for Beowulf

Jakob Østergaard jakob at unthought.net
Sat Aug 25 17:29:38 EDT 2001


On Sat, Aug 25, 2001 at 10:39:59PM +0200, Jakob Østergaard wrote:
> On Thu, Aug 16, 2001 at 02:52:23PM +0000, Mark Hahn wrote:
> > > >    we as a group of four students are *also* thinking
> > > > of implementing Network RAM for a beowulf cluster
> > > > (assuming 100Mbps Ethernet ) whereby each node in the
> > 
> > I'm always puzzled why people want to keep trying this:
> > have you considered the fairly breathtaking latency of 
> > "sharing" pages over a net?  do you really have apps that can 
> > tolerate that kind of latency?
> 
> What latency ?   ;)
> 
> I have 100 usec ping latencies on my network.  Bandwidth ~ 8-12 MB/sec
> 
> I have 8 ms seek latencies on my harddrives. Bandwidth ~ 12-16 MB/sec

Sorry for following up on my own post, but this needs clarification:

I'm referring to network swap here.  Swapping over fast local networks
can absolutely make sense.

If you were referring to running separate threads of the same process on
multiple nodes in a cluster, sharing the same meory space over the network, I
completely agree with you.  That's not practically possible when the execution
environment (the operating system kernel) doesn't understand the code
(compiler-generated native machine-code) it executes.

Even MOSIX migrates complete processes.  For good reason I presume  :)

-- 
................................................................
:   jakob at unthought.net   : And I see the elder races,         :
:.........................: putrid forms of man                :
:   Jakob Østergaard      : See him rise and claim the earth,  :
:        OZ9ABN           : his downfall is at hand.           :
:.........................:............{Konkhra}...............:

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