L1
Silicon
Sets cost per token
The accelerator and its generation, with the memory, interconnect, and power it ships with. It
converts energy into tokens and sets the floor on cost per token for everything above it. Not all
tokens are equal: a low-latency token on a general-purpose GPU can cost more than the same token
on purpose-built silicon.
L2
Capacity
Sets effective cost
How much silicon you hold, where it sits, and how much of it does useful work. Reserved or
on-demand, one region or another, scaled up or scaled to zero, all decided against a traffic shape
that rarely matches the commitment. Idle capacity raises the effective cost of the work that does run.
L3
Inference stack
Suppresses repeated work
The serving software: engine, KV cache management, batching, and the prefill and decode split.
Usually the single largest source of optimization, and the first layer where consumption is
suppressed rather than merely priced. Cache hit rate is the number that matters most, and it is
won largely through prompt and prefix stability.
L4
Model + quantization
Right-sizes what runs
Which model runs, at what numeric precision, and with what adapted weights. Running a
frontier-scale model for a trivial task is the classic waste. Right-sizing is what pulls
multiplicative work back toward linear; precision and adapter strategy set what each token costs
once the class is settled.
L5
Routing and governance
Bounds fan-out and retries
The control plane in front of everything else: which model serves each request, caching at the
gateway, budgets and quotas, and the guardrails that bound agent fan-out and retries. It is the
only layer that can decide a request needs no model at all, and the only one that can stop a
workload consuming without limit. Routing is an optimization; a circuit breaker is a containment.
A workload with no ceiling has no worst case.