Equation 2 · Part 6 · An Optical Fabric Turns Off-Package Memory Into an Extension of the Die
Symbol P_cu
What this part means
u occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.
Its job in the formula
u occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.
Full expression→Symbol P_cu→Article meaning
The passage around this formula
I define a compute-to-memory locality index, L , as the ratio of two bandwidth-per-joule figures: the realized random-access bandwidth a system can sustain across its full memory pool, divided by the power it costs to sustain that bandwidth, computed once for the optically unified case and once for the same total memory capacity attached the conventional way — as edge-limited HBM and DDR stacks wired electrically to a die of the same process generation. Here BW is realized, measured random-access bandwidth in bytes per second — not a marketing peak, not a sequential-streaming figure, since random access is what most large-model inference and any pooled-memory workload actually demands — and…
Learn the underlying idea
A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.
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