On Sat, Apr 04, 2009 at 04:06:22PM +0200, Eugen Leitl wrote: > On Fri, Apr 03, 2009 at 01:32:13PM -0700, Greg Lindahl wrote: > > > > Will have to do with embedded memory or stacked 3d memory a la > > > http://www.cc.gatech.edu/~loh/Papers/isca2008-3Ddram.pdf > > > > We've been building bigger and bigger SMPs for a long time, making > > changes to improve the memory system as needed. How is multicore any > > Off-die memory bandwidth and latency are limited, so many codes > start running into memory bottlenecks even at moderate number > of cores
Exactly like shared-bus multiprocessors. The incremental method of solving this is what Opteron/Nehalem does. The more radical method is what Origin/Altix did. It all comes down to how many pins you're willing to commit to memory and how few pins you can squeeze a memory bus down to; once you bump up against that limit, then you need an improvement in packaging, which is no more radical than what Opteron/Nehalem or Origin/Altix did. And, of course, all this was invented before Opteron or Origin. The sky is not falling. -- greg _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
