[Beowulf] SCI Socket latency: 2.27 microseconds
bill at cse.ucdavis.edu
Mon Mar 1 16:38:52 EST 2004
> well, Quadrics now claims 1.8 us MPI latency:
Note the title says "sub 2us" and the body says "close to" 1.8us.
Of more interest (to me) is that further down they say:
In the next quarter, Quadrics will announce a series of highly competitive
switch configurations making QsNetII more cost-effective for medium
sized cluster configuration deployment.
Sounds like more competition for IB, Myrinet and Dolphin. Hopefully anyways.
Cool, found a quadrics price list:
Looks like $3k per node or so for 64, and $4k per node for 1024, I'm guessing
that is list price and is somewhat negotiable.
According to my sc2003 notes the Quadrics latency was:
100ns for the sending elan4
300ns for the 128 node switch and 20 meters of cable
130ns for the receiving card.
2420ns for two trips across the PCI-X bus and a main memory write
2950ns for an mpi message between 2 nodes.
Anyone know what changes to get this number down to 1.8us - 2.0us?
> higher bandwidth. yes, some vendors (esp IB) are pushing PCI-express
> as bandwith salvation, but afaikt, none of my users need even >500 MB/s
> today. it doesn't seem like PCI-express will be any kind of major win
> in small-packet latency...
Anyone have an expected timetable for PCI-express connected interconnect
Anyone have projected PCI-express latencies vs PCI-X (133 MHz/64 bit)?
Computational Science and Engineering
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