IMC- Integrated Memory Controller
1) It won't fit in with their intelligent power management technology.
2)It will bottleneck their upcoming I/O Acceleration Technology (IOAT
3) If the controller remains on the northbridge, the transition to new memory modules will be easier.
How they solved the prob of no Integrated Memory Controller
1)they came up with their advanced smartcache technology
2)the come up with their smart memory access technology
3)they used the silicon which could have been used in an IMC to improve their cache.
The reason Core has no IMC, in my opinion, is they did not need the performance boost or extra bandwidth. FSB is aging, true, but in single socket DTs is just as good or better than HTT. HTT only really shines when you scale multiple sockets.
In the new microarchitecture, Intel has redesigned the notrthbridge for servers to give each socket it's own FSB. The northbridge now has 64 megs of cache itself to speculatively track which core has the most recent cache refresh and "traffic" cops the data to each core as I understand it. This bridgeport chipset should eliminate the cache coherency problem of more sockets sharing the same FSB -- the 4-way and 8-way space is owned by AMD, but until we see if the Snoop Filter eliminates the cache coherency problem, the chapter is not finished yet.
Now, Intel has held the position that integrating the IMC actually hurts flexibility to adopt new memory technologies, and they are correct on this -- as a result, you work to hide that latency and decrease the dependency on bussing -- that is why Intel chooses to employ large caches, large cache hides this latency, especially if you have a very good prefetch logic built into the chip. While the pipeline is crunching, the prefetcher is working to keep the correct data in cache sorta parallel computing/caching.
The question is, why do people fixate on the FSB when the real proof is inthe pudding? What I mean by that is, if a Core 2 at 2.6 GHz, consting 550 bucks spanks an FX-62 why would the fact that a FSB is used make a difference?
FSB and it's draw backs are only really critical in the 4-way and 8-way servers as it does not scale as well as the NUMA model.
Jack
Word.
Well he did a nice bullet form of analyzing the question, points 1,2 of the first group are not correct, but the last one is....and the solutions are all true -- except in different context. IMCs solve a problem, Intel's mehtods just go about a different way of solving that same problem -- memory latency.
I hear rumors that Intel may integrate the memory controller in certain product lines in 2007... but right now that is just rumor -- Rattner always dodges the issue.
Yeeeeaaaahhhhh, my first post!!!
First of all, I am an AMD fanboy, but thats not to say that I don't look at Intel in a good light. That being said, JumpingJack, I'm happy to see someone speak intelligently about Intels FSB vs IMC. But their current setup wont last too much longer.
Sure an 800MHz FSB was ok for dual-channel (DC) DDR-400, but with DDR2 it was a joke. So then they increase it to 1066 for DC 533, which is still a joke. Blackford/Greencreek are 1333, which is good (DC 667), but they need it at least 1600 for DDR3. Unfortunately, this probably won't happen anytime soon because Intel never bothers to give their northbridges die shrinks. Plus, rumor has it that CSI is lagging and might not come out until 2009, ouch.
What this means for Intel is when it comes time for DDR3, Intel will be at a loss. They will most likely only be able to support DC DDR3-800, whereas AMD will have HT3.0 at 5200MHz effective which will be able to handle DC DDR3-1600 and even be able to handle next generation memory as well. Also, AMD's next memory controller is suppose to support DDR2, DDR3 and FB-DIMM all at once, allowing AMD to be more flexible, just like Intel's off-die northbridge.
Lastly, AMD's 1000MHz FSB is equivilent to Intel having an 2000MHz FSB, so that is why people say AMD has a 2000MHz FSB.
:idea: ::I'm not sure if AMD is going to or can do this, but HT3.0 with a slight overclock to 5333 could handle Quad-Channel DDR3-1333. That would be insane.