cost

Switch radix decides it, and at 10,000 endpoints the answer sits right at the boundary for current high-radix switches. The arithmetic, what a third tier costs in switches, optics and power, and the two designs that avoid it entirely.

Ten thousand requests a second is a fleet of hundreds of nodes, a router that has to know what every replica is caching, and an SLO pair that decides the batch on every one of them. Here is the sizing chain, node by node.

Six steps forward from traffic, never backward from an available GPU count. The one input that has to be measured rather than derived, the headroom that is not optional, and the utilization term that moves cost per token more than any tuning flag.

The self-hosted price falls with volume and the API price does not, so the two cross at a token rate. Where that crossing sits, the fixed cost floor that makes low volume expensive, and the three reasons that override the arithmetic in both directions.

The cheapest correct answer beats the best answer at scale, so routing is a cost problem with a quality floor. The three routing signals that work, the cascade that trades latency for cost, and the measurement that catches quality loss no latency dashboard shows.

Benchmark rankings answer a question your product did not ask, and candidates usually differ more in what they cost to serve than in what they can do. The four axes in elimination order, and the deployment floor that rules candidates out before quality is discussed.

Fleet dollars per second over tokens per second, times a million: a worked $2.78, the utilization term that turns it into $6.94, and why batch is the lever that moves it by 50x.

fp8 halves the bytes per decode step and doubles the compute peak, but the all-reduces and launch overhead do not shrink, so the measured gain is 1.5x at a fixed batch and about 2x once the freed memory raises the batch. The chain, with the step-time table.

Dollars per FLOP from the GPU price and the MFU, times 6N: a 70B training token costs about three quarters of a microdollar, and the whole 15T-token run follows in one multiplication. The chain, the comparison to an inference token, and why the training token is cheaper.

One gives you POSIX semantics and hundreds of gigabytes per second at a price per terabyte that hurts at petabyte scale. The other is cheap and durable and answers a first byte in tens of milliseconds. The cost arithmetic that makes most clusters run both, and the metadata limit that decides how you shard.

Three networks, not one, and the mistake that hurts most is putting two of them on the same wires. The port and switch counts for each, the cable plan, the split of the bill between switches and optics, and the two decisions that are hard to change once the cluster is racked.

Spot is 60% cheaper until the preemptions eat the discount. The expected-loss formula (waste per preemption = half the checkpoint interval plus restart), the break-even worked at three cadences, the checkpoint cost that pushes back the other way, and the gang arithmetic that says which jobs must never be on spot.

Committed capacity is cheaper per hour and cannot shrink, so the decision is a utilization break-even, not a discount. The arithmetic for where the reserved baseline should sit, why the p50 of steady demand is the target, and how on-demand, spot and capacity blocks absorb everything above it.

Every replacement costs a spare, a maintenance window and a return process; every device kept costs the risk of a job it will fail. Four triggers that decide it without a case-by-case argument, the arithmetic that sets the repeat threshold, and why the device's history beats any diagnostic result.

A replica takes 70 seconds to become useful and the burst arrives in 60, so the autoscaler cannot win the first minute; the warm pool has to. The leading signal, the cooldowns derived from the cold start, the warm-pool size from Little's law and the burst profile, and the cost of every second of cold start left in.

Any engineer can cut cost. The question is whether you measured what it cost you elsewhere, and whether you knew that before you shipped it. The three mechanisms that produce most of the savings, and the metric you have to watch on the way down.