T wrote:
On 12/28/2017 05:03 PM, Rene Lamontagne wrote:


The i9 is out now, 10, 12 and 18 core, Sells for up to $2600.00 for
the i8 core.
Apple is supposed to be using them in their Super high price iMacs
which start at $4999.00 up to about $13000.00

Me thinks a waste of money, but I haven't tried one. A fast
NVMe drive makes all the difference int he world.

18 cores? Reminds me of the commercials for shavers that
make fun of multi blade shavers by showing a 10 blade shaver.

How in the world will all 18 cores talk over the same
busses? Oh well...

The previous generation of monsters like that,
used counter-rotating rings. Which doesn't sound
all that good. The newer generation uses a mesh
(bus grid). There are some pictures of the old and
new here. There were also some pictures on anandtech,
showing how the rings worked on the old high-core-count
ones.

https://wccftech.com/intel-skylake-x...-interconnect/

The AMD "Infinity Fabric" is some kind of mesh too,
but I can't find any really exceptionally detailed
pictures. I don't like "fluffy cloud" pictures for
tech, if I can avoid them.

Apparently, both the AMD CPU and GPU use that
connection method. But again, without pictures,
it's hard to say why in the case of a GPU.

Where the caches are located on these things is
important. If the interconnect between cores has
a high latency, it doesn't take much to make a
"far" cache, be about the same speed as a main
memory access. Making it functionally useless.

So those papers all those grad students wrote
twenty years ago, are finally coming to pass.
(I had an IEEE membership back then, and some
of the CPU papers were a practical joke, because
at the time, who could afford to build them ?)

The thing is, with modern silicon, there is plenty
of room for goofy stuff. But it costs money
and takes time to design those gates, and that's
the really amazing part of these things - knowing
how hard it is to make bulletproof things
that are ready for production. There's probably
no microcode to patch a bug in the mesh station.
So let's hope they started the mesh project
ten years ago, and had plenty of time to test
prototypes or whatever.

Paul