> > I thought the thrust of the original post was that you can > build now a cheap IB cluster with up to 24 nodes. The > subsequent discussion was around questioning whether you need > IB for up to 16-24 nodes. > The advantage you point to is for 32 nodes. There is no > question that IB is much better at this scaling point for > many codes, not just WRF. > I used to think that the typical break point is about 16 > nodes. We have a lot of app data on our web site which > confirm this and will be looking into how (if at all) quad > cores change this. >
With more cores on a single node, the IB benefits are seen in much lower number of nodes. I am testing some applications on a new cluster that I have (dual sockets quad core Barcelona), and my first results are with Fluent new benchmarks. I will have the numbers posted soon, so you all can take a look. For 2 nodes, IB shows an average of 15-20% higher performance then GigE, and this gap gets bigger with cluster size. At 4 nodes the difference was 40-50%. Even more important, 3 nodes results with IB were higher then 8 nodes with GigE, and GigE stop scaling after 3-4 nodes (performance numbers were flat after 3-4 nodes). This is only one example, I know, but I am sure there will be many more. I personally going to check it on more applications, and would appreciate any suggestion on other applications people have interest to check. > As far as the games are concerned never underestimate what > people can do if sufficient and affordable resources are > provided. If the opposite were true we'd be still staring at > black and white/green screens and playing packman. Game > developers have to offload a lot (too much in fact) to a > client out of necessity, not because they want to (BTW, there > are amazing exploits because of the lags and the way the > clients are built). Having said that there is no question > that IB is hardly applicable to MMORPGs on the scale they > are, probably not even for LAN parties. However a small > cluster for real time ray tracing might be a good proposition. > > Igor > _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
