On Mon, 27 Jul 2009, Dave Youatt wrote:
Greg, those are compelling numbers for the new Nehalem processors.
Great news for postgresql. Do you think it's due to the new internal
interconnect...
Unlikely. Different threads on the same CPU core share their resources, so they don't need an explicit communication channel at all (I'm simplifying massively here). A real interconnect is only needed between CPUs and between different cores on a CPU, and of course to the outside world. Scott's explanation of why SMT works better now is much more likely to be the real reason. :-) there's also this interconnect thingie between sockets, cores and memory. Nehalem has a new one (for Intel), integrated memory controller, that is. And a new on-chip cache organization.
I'm still betting on the interconnect(s), particularly for bandwidth-intensive, data pumping server apps. And it looks like the other new interconnect ("QuickPath") plays well w/the integrated memory controller for multi-socket systems.
Greg, in your spare time... Also, curious how Nehalem compares w/AMD Phenom II, esp the newer ones w/multi-lane(?) HT
And apologies to the list for straying off topic a bit.