- Oct 14, 2003
So Intel says on-die fabrics need 0.1pJ/bit, and Foveros requires 0.3pJ/bit. Still a fair bit higher, but organic interposers are over 1pJ/bit, and EMIB is slightly below 1pJ/bit.You need hybrid bonding to get close to monolithic. Foveros has a smaller bump pitch than EMIB, which is probably why it's used here, but it's still not quite monolithic.
When you are talking about datapaths for I/O, then it cannot be shut down as readily as the individual blocks do, because they need to meet QoS and bandwidth/latency requirements. Also because you need to serve every block that uses the bus. If you have 50 blocks on a bus, but only one is active, you still need to have the whole bus online.
It seems that on a higher level you can use things as power gating to lower power use, but they don't use it for say, the decoders as it's too latency critical.
So theoretically it should offer both faster on/off transitions for the chipset actually allow it to reach much lower power idle(and/or more often) and also reduce the absolute floor of power the communication line uses. This means the ~1.5W or so TDP of the on-package chipset is often reached even in very light load. Yes you can get that really low in idle, but it's very easy to knock it off that state.
That is theory of course. Atom didn't benefit from things being on-die until Silvermont when they updated to a proper on-die bus.
This is an opportunity. I think there's a chance for them to improve this greatly, though still playing catch up at this point.Unfortunately, I think you'll be disappointed, but I hope my pessimism ends up being incorrect.
Also, good to know davidbepo is a crock.