[Beowulf] slightly [OT] smp boxes
larry.stewart at sicortex.com
Sun Oct 19 13:41:30 EDT 2008
On Oct 17, 2008, at 10:06 PM, Joe Landman wrote:
>> The Sicortex system has lots of cores and some of their smaller
>> development systems and might qualify if the goal is to research
>> SMP, NUMA, and single system memory image.
> I don't know if you would call them SSI, and I don't remember if
> they have strict coherency within them. This said, they have a very
> fast and scalable fabric. It is an interesting system. Not a
> commodity box, but quite interesting.
The SiCortex systems are clusters of 6-core SMPs. There is no load/
store access to memory on other nodes, although the interconnect is
fast enough to make software access to remote memory quite interesting.
All the nodes typically run the same kernel image, but it isn't an SSI
I've been coding shmem and GASnet implementations for the SiCortex
interconnect recently, and on the older 500 MHz systems a "put" takes
about 800 ns and a "get" takes a little under 3 microseconds before
any particular effort on performance. These are in line with MPI
PingPong times. As far as I can tell, these will scale with clock
speed on the 700 MHz systems.
On the remote-paging side, I put together a prototype that gets about
2 GB/sec and 64K page fault latencies under 100 microseconds, again,
I'm kind of hoping some academic departments use the iron for
operating systems, programming, and communications research. It's
all open source after all. I am kind of amused by all the press and
angst about "multicore", like 2, 4, or 8 cores are even an interesting
problem. It seems to me that 100s of cores are pretty well
understood, but when you get to 1000's, there is a lot more to learn.
Of course I had a 5 cpu workstation back in 1986 or so...
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