amd dual core preview

[saaya]

/me sends Saaya a bill

here you go

They didn't necessarily have to be using a crossbar, could have simply had an arbiter.

i thougt tis the same with a different name?

Can we vote on the reason? From the info I've seen, their is still only one interface, even though it is two seperate die (i.e. not 2 independent busses... still in same physical package, same pin count AFAIK).

hmmm but that would mean each core has its own interface plus an arbiter as there will also be single coe chips based on the same architecture. but then i dont get how they hook up the cpus...
hmmmm maybe one arbiter, lets say no1 is hooked up to the system and then shares the bus with cpu1 and the other arbiter wich forwards the infos to cpu2?

cpu2<-arbiter2<-arbiter1->cpu1

What added bandwidth? Regarding making more sense... don't forget that Intel still has the mem controller outboard, so everything funnels through the one interface In general tho, no considering the appetite their CPUs have for bandwidth, none of their roadmap makes a ton of sense from here.

hummmz wth was i talking about? hmmm added bandwidth? lol my bad

Coherency could be handled on die with communication between the two cores... as long as the mem controller is outboard of the CPU, then two seperate interfaces for the cores would actually work better. Basically think of the mem controller, crossbar, and I/O interface that resides onboard for the A64 being all together in the outboard NB for the Intel cores. By having seperate busses, one could be accessing memory while the other could be accessing Gfx, HDs, etc., plus effecient combining and ordering of accesses could be handle in the outbound NB more effectively since it is where the mem controller and I/O interfaces are.

hmmm yeah, but if its done right a larger shared bus could be faster because you save bandwidth for data that both cpus need at the same time, no?
my bad, its very unlikely that the two cores will be working on the same thing and requesting the same data anyways since they wont be working on the same thing at the same time anyways

ok, just wondering, wut would the over clocking be like? ive never used or seen a 2 cpu system personally, would u have to oc the cores seperate? or would they oc at the same time just having to mess with one setting?

hey trance565, welcome to XtremeSystems
on a dual cpu system you have to clock both cpus at the same speed, i think thats necessary to keep them working efficiently together.

and about a dual core cpu, it would be the same.
but yonah can disable one cpu core if not needed, and i think they are planning to let yonahs successor even have independant vcore control and independant clockspeeds for each cpu.

thats what i thougt of once, and i told it to amd when i met them at cebit. i hope they liked the idear and will implement it. lets say you run an app that is heavily single threadded, then wouldnt it be cool if the dual core cpu would disable one of its cores? then it could clock its first core to a much higher speed still staying in the termal envelope and still using the same amount of energy wich would give you a much better result in that single threadded app than having two slower clocked cores, one pretty much idling and the other one crunching really hard. and as soon as you start another second demanding thread then the core1 clocks itself down to normal speeds and the core2 starts up again and you have two cpus crunching, each on one app

this would have to be controlled by the os though i think, as implementing it into a cpu would be very hard to configure i guess... but if it has to rely on the os it means MS, and we all know what this means... it would take years for them to implement it, and by then probably all apps would be highly multithreadded so it woudl be useless...

too bad...

cadaveca i still dont really get what your talking about, sorry :/

EMC2 ahhhh so thats an arbiter... you explained it really well, no need for a pic i think
the dma example is pefect, the arbiter is like having two hdds hooked on one bus, as slave and master drive, while the crossbar is like having both hdds hooked up in raid0
more or less...