PCI-64: how to find

Mark Hahn hahn at physics.mcmaster.ca
Mon Feb 25 09:17:16 PST 2002

> >      Is there (objective) comparison chart (bandwidth + latency) of
> > Gigabit ethernet vs Myrinet vs Dolphin ?
> It's impossible to get an objective comparaison, there is too many 

perhaps to get a complete and comprehensive picture.  but I don't see
why some simple but useful metrics can't be had.  for instance,
suppose I just want to know the latency for a zero-sized packet between
just two machines.  I don't see why CPU/PCI/etc would make much of a 
difference here.  sure, it's not enough of a picture to start ordering
hardware, but it's a start (and a fundamental number).

for instance, conventional wisdom seems to be that 1000bT doesn't much
improve the ~50-100 uS latency shown by 100bT for tinygrams.  does anyone
have good measurements on that, particularly with irq-mitigation turned *off*?

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