erik quanstrom wrote:
I think the reason why you didn't see parallelism come out earlier in
the PC market was because they needed to create new mechanisms for I/O.
AMD did this with Hypertransport, and I've seen 32-core (8-socket)
systems with this. Now Intel has their own I/O rethink out there.
i think what you're saying is equivalent to saying
(in terms i understand) that memory bandwidth was
so bad that a second processor couldn't do much work.
Yes bandwidth and latency.
but i haven't found this to be the case. even the
highly constrained pentium 4 gets some milage out of
hyperthreading for the tests i've run.
the intel 5000-series still use a fsb. and they seem to
scale well from 1 to 4 cores.
Many of the circuit simulators I use fall flat on their face after 4
cores, say. However I blame this on their algorithm not hardware.
I wasn't making an AMD vs Intel comment, just that AMD had created HTX
along with their K8 platform to address scalability concerns with I/O.
are there benchmarks that show otherwise similar
hypertransport systems trouncing intel in multithreaded
performance? i don't recall seeing anything more than
a moderate (15-20%) advantage.
I don't have a 16-core Intel system to compare with, but:
http://en.wikipedia.org/wiki/List_of_device_bandwidths#Computer_buses
I think the reason why Intel developed their Common Systems Interconnect
(now called QuickPath Interconnect) was to address it's shortcomings.
Both AMD and Intel are looking at I/O because it is and will be a
limiting factor when scaling to higher core counts.
- erik
