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Chapter 1110 min readReviewed 31 August 2026

Formulas, glossary, and source ledger

The reusable math, vocabulary, caveats, and dated primary sources behind this playbook.

On this page
  1. Formula sheet
  2. Glossary
  3. Source ledger
  4. Maintenance policy
Reusable math

Formula sheet

Use these for first-pass planning, then replace estimates with engine and workload measurements.

weight bytes ≈ parameters × bits per weight ÷ 8
Weight-only storage; scales/metadata and higher-precision layers add overhead.
KV bytes = 2 × layers × KV heads × head dimension × bytes × Σ live tokens
Standard attention; use KV heads, not query heads.
E2E ≈ TTFT + (output tokens − 1) × TPOT
Simple response approximation.
mean in-flight requests ≈ request rate × mean service time
Little’s Law for mean concurrency; tails are higher under bursts.
replicas ≈ ceil(target demand ÷ goodput/replica × (1 + reserve fraction))
Capacity that passes the service contract; reserve fraction is a decimal (20% = 0.20).
$ / 1M output tokens = deployment $/h × 1,000,000 ÷ successful output tokens/h
All loaded cost; only SLO-passing output in the denominator.
break-even utilization = committed effective rate ÷ on-demand rate
First-pass commitment test.
scaling efficiency = throughput at N ÷ (N × throughput at 1)
Same workload and quality target.
Shared vocabulary

Glossary

Accelerator
A device optimized for parallel compute; GPUs are one accelerator family.
HBM
High Bandwidth Memory packaged close to the accelerator. Capacity and bandwidth are distinct.
GDDR
Graphics memory used by many PCIe accelerators; generally a different capacity/bandwidth/power profile from HBM.
TTFT
Time from request submission to the first output token, with the measurement boundary stated.
ITL / TPOT
Actual intervals between tokens / average time per generated token after the first.
Goodput
Useful work completed while meeting the chosen latency, quality, error, or deadline contract.
KV cache
Attention keys and values retained for live tokens so previous context is not recomputed at each decode step.
Continuous batching
Rebuilding the active batch at generation steps so finished work leaves and new work enters.
Tensor parallelism
Sharding operations inside model layers across devices, requiring frequent collectives.
Data parallelism
Replicating a model or training state so different requests/batches run on different workers.
MIG
NVIDIA hardware partitioning on supported GPUs with defined compute/memory slices and isolation.
Time-slicing
Scheduling multiple processes on one GPU without hardware memory/fault isolation.
SXM / OAM
High-power accelerator module form factors used on platform baseboards; not ordinary PCIe cards.
NVLink / Infinity Fabric
Vendor scale-up links used for faster device-to-device communication within supported systems.
RoCE
RDMA over Converged Ethernet, used for low-latency/high-throughput network communication.
Quantization
Representing some weights, activations, or KV state at lower precision with hardware, kernel, and quality implications.
Prefix cache
Reuse of KV blocks for token-identical prefixes across requests.
SLO
A measurable service-level objective such as p99 TTFT, error rate, quality, or job deadline.
Evidence model

Primary-source ledger

All sources below were checked 31 August 2026. Live documentation is marked because compatibility, specifications, and commercial terms can change.

Vendor specifications

Official documentation

Primary papers

Cost and procurement

Keep the playbook honest

Maintenance and claim policy

Claim classPolicy
Architecture concept / formulaLink primary paper or official technical documentation; revise when the model assumptions change
Hardware specificationName exact variant and scope; link the live vendor page/data sheet; store last-reviewed date
Software compatibilityLink the current support matrix instead of copying long version tables
Price / quota / availabilityNever present as evergreen; store provider, region, shape, term, currency, source and verifiedAt
BenchmarkPreserve complete configuration, workload distribution, SLO, quality, raw result and date
Vendor performance or TCO claimLabel as vendor-reported; retain conditions; do not generalize into a universal multiplier
Preliminary productMark preliminary and date the statement; do not use roadmap availability as committed supply