First sightings: 6-core Opteron
Techreport published an article about the upcoming 6 core Opteron “Istanbul”. AMD seems to have working silicon. This is an especially interesting news for our X4600 as this system contains a feature to reduce cache coherency traffic on the Hypertransport. The more procs and cores you have in your system, the more this starts to be a challenge and. An system with reduced cache coherency traffic would leave more bandwith for other traffic. The X4600 - a really fast implementation of an 8-socket Opteron system - would be even faster with such reduced traffic. AMD solves this with a directory of memory pages cached in the processor:
Part of the answer, it seems, may be a feature new to Istanbul that AMD calls HT assist (presumably for HyperTransport assist). This feature is what the company calls a probe filter (and may more commonly be called a snoop filter) that functions to reduce traffic on socket-to-socket HyperTransport links by storing an index of all caches and preventing unnecessary coherency synchronization requests
And you have to keep in mind: A X4600M2 with Istanbul would be an 48 core system on 4 rack units. As i wrote before: Interesting technology.