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Equation 3 · Part 7 · The Network Is the Computer Again

Denominator: m+p-1

p−1m+p−1,\frac{p-1}{m+p-1},
m+p−1m+p-1

What this part means

The complete quantity below the fraction bar; it must be nonzero for this division.

Its job in the formula

m+p-1 occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.

The passage around this formula

Pipeline parallelism splits the model by depth, giving each device a contiguous run of layers. The traffic is point-to-point rather than collective — activations forward, gradients backward, between neighbouring stages only — and the volume is modest. Its cost is not bandwidth but idleness. GPipe’s contribution was to split each batch into micro-batches so that stages could work concurrently instead of waiting for a whole batch to traverse the pipeline [ 6 ] . With p stages and m micro-batches, the standard accounting gives a bubble fraction of p−1m+p−1\frac{p-1}{m+p-1}. which says the only cure for pipeline idleness is more micro-batches in flight, and micro-batches cost memory. Narayanan and…

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Learn the underlying idea

A fraction a/b means a divided by b. The top number is the numerator; the bottom number is the denominator, and it cannot be zero.

Open the illustrated fractions: division written vertically guide →

Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.