On Fri, Sep 17, 2010 at 10:53:11AM -0400, Lawrence Stewart wrote: > One of the other ideas at SiCortex was that a slow core wouldn't > affect application performance of codes that were actually limited by > the memory system. We noticed many codes running at 1 - 5% of peak > performance, spending the rest of their time burning a lot of power > waiting for the memory. I think this argument has yet to be tested, > because the first generation SC machines didn't actually have a very > good memory system.
This is a somewhat well-studied thing. * Blue Gene has a node with a slow cpu, and a better memory system than you guys had. There are probably some published studies. * On x86, it's not hard to slow down the memory system by reducing the # of channels, putting in slow memory, or adding more devices such that the bus slows down. And sometimes it's possible to get the same cpu with ddr2 and ddr3. * There have been a ton of academic papers over the years exploring how memory bound various codes are. -- greg _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
