The l
value
• l is
a purposely vague quantity
–The
cost is not known and cannot be known because every machine is different
•There
is no agreement yet on the parallel architecture
• l
depends on bandwidth, engineering, interfaces, mem
–The
cost cannot be a single
number because of network
topology, conflicts, etc.
–Optimizing
for communication -- if possible -- should be done by the compiler not a
programmer
