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06 Numbers and Powers

How to Compare AI Inference Chips and Cloud Providers

Card No. 06·62414 · Updated · Standard formula, shown below

This guide walks you through comparing AI inference hardware and cloud offerings so you can pick the option that best fits your latency, cost, and throughput needs. You’ll learn what specs matter, how to benchmark fairly, and how to read pricing sheets without getting lost. Before you start, have a clear idea of your model type (e.g., transformer, CNN), expected request volume, and latency targets—these will drive every comparison.

What You’ll Need

  • Model details: architecture, parameter count, input/output sizes
  • Performance requirements: target latency (e.g., p95 < 100 ms), throughput (requests per second)
  • Budget constraints: per-request cost or monthly spend cap
  • Access to a few representative prompts or inputs for testing
  • A basic understanding of cloud billing (instance types, regions, egress fees)
  • Optional: a benchmarking script (e.g., using Python or a load-testing tool)

Step-by-Step

  1. Define your workload profile. Write down your model’s size (e.g., 7B parameters), typical input length (e.g., 512 tokens), and output length (e.g., 128 tokens). Also note if you need batch processing or real-time streaming.
  2. List candidate chips and cloud instances. Common inference chips include NVIDIA GPUs (A100, H100, L4, A10), AMD Instinct, Google TPU, AWS Inferentia, and Qualcomm Cloud AI. For cloud providers, note the specific instance types that use these chips (e.g., AWS EC2 Inf2, Google Cloud TPU v5e, Azure ND-series).
  3. Compare raw specs first. Look at memory bandwidth (GB/s), on-chip memory (HBM size), FLOPS (FP16, INT8), and power draw. Higher memory bandwidth often matters more than raw FLOPS for autoregressive decoding.
  4. Check software support. Ensure your framework (PyTorch, TensorFlow, ONNX Runtime) has optimized kernels for the chip. Look for documentation on quantization (e.g., INT8, FP8) and compilation tools (e.g., TensorRT, Neuron, OpenVINO). Poor software can negate hardware advantages.
  5. Estimate cost per inference. For cloud, use the on-demand hourly price and divide by the number of inferences per hour you can achieve. For on-prem chips, include hardware cost, power, cooling, and maintenance over a 3-year lifespan. Don’t forget egress fees if you move data out of the cloud.
  6. Run a real benchmark. Use your actual model and representative inputs. Measure latency (p50, p95, p99) and throughput (requests/second) under a realistic load. If possible, test with the same batch size and concurrency that your production will use.
  7. Evaluate scaling and flexibility. Can you add more instances easily? Is there a serverless or autoscaling option? For on-prem, how long does it take to deploy new chips? Cloud providers offer elasticity, but at a premium.
  8. Check region availability and compliance. If your data must stay in a specific region, verify that the chip/instance is available there. Also check for certifications (e.g., SOC 2, HIPAA) if needed.
  9. Calculate total cost of ownership (TCO). For cloud: sum of compute, storage, egress, and any support fees. For on-prem: hardware, power, cooling, facility space, and IT staff time. Compare over 1- and 3-year horizons.
  10. Make a decision matrix. Score each option on latency, throughput, cost, ease of use, and scalability. Weight each factor according to your priorities (e.g., 40% cost, 30% latency, 20% throughput, 10% ease).

Common Mistakes

  • Comparing peak FLOPS instead of real throughput. Peak numbers rarely translate to actual performance due to memory bottlenecks and kernel inefficiencies.
  • Ignoring memory bandwidth. For autoregressive models, memory bandwidth is often the limiting factor, not compute.
  • Using a single prompt for benchmarking. Real workloads have varying input lengths and output lengths. Test with a mix.
  • Forgetting about cold starts. Serverless offerings can have high latency on the first request after idle.
  • Overlooking egress fees. Moving data out of a cloud provider can add significant cost, especially for high-volume inference.
  • Assuming all cloud instances of the same chip perform identically. Neighboring tenants can affect performance on shared hardware.

Tips

  • Use a standard benchmark like MLPerf Inference for a rough comparison, but always validate with your own model.
  • Look for committed-use discounts (e.g., savings plans, reserved instances) if you have steady workloads.
  • Consider quantization. INT8 can double throughput on many chips with minimal accuracy loss. Test with your model.
  • Check if the provider offers a free trial or credits to test their hardware without upfront cost.
  • Monitor performance over time. Cloud instances can be noisy; run benchmarks at different times of day.
  • Think about the whole pipeline. Preprocessing and post-processing can become bottlenecks. Include them in your benchmark.

Troubleshooting

  • Benchmark results are inconsistent. Run multiple iterations and use the median. Ensure your test environment is isolated (e.g., no other jobs on the same instance).
  • Model doesn’t run on the chip. Check for missing operators or unsupported layers. Try converting to ONNX or using a provider-specific SDK. If unsupported, consider a different chip or fallback to CPU.
  • Latency is higher than expected. Check if the model is using dynamic shapes; fix input dimensions if possible. Also check if the instance is throttled or if you’re using a burstable CPU.
  • Costs are higher than estimated. Review your egress usage and consider caching outputs. Also check if you’re using more instances than needed due to inefficient autoscaling.
  • Provider’s documentation is unclear. Contact support or look for community forums. Many providers have example code for popular models.

Frequently Asked Questions

What is the most important spec for inference?

For most LLM workloads, memory bandwidth is critical because decoding is memory-bound. However, for small models or heavy batching, compute (FLOPS) may matter more. Always benchmark with your specific model.

Should I use a cloud provider or buy my own chips?

If you have predictable, high-volume workloads, on-prem can be cheaper in the long run. If your demand varies or you need to scale quickly, cloud offers flexibility with higher per-request cost.

How do I compare costs across providers?

Calculate cost per 1,000 inferences for your model, including compute, storage, and egress. Use the same benchmark to get throughput, then divide the hourly cost by the number of inferences per hour.

What is the difference between latency and throughput?

Latency is the time for a single request to complete (e.g., 200 ms). Throughput is how many requests you can process per second (e.g., 50 req/s). They are related but not the same—you can have low latency but low throughput if concurrency is limited.

Can I use any GPU for inference?

Yes, but performance varies widely. Consumer GPUs like RTX series can work for small models, but for production, data center GPUs like A100 or H100 offer better memory and reliability. Also, some cloud providers offer specialized inference chips like Inferentia that may be more cost-effective.

How important is software support?

Very. A chip with great specs but poor software will underperform. Check for mature libraries, quantization tools, and community support. For example, NVIDIA has CUDA and TensorRT, while AWS Inferentia uses the Neuron SDK.

Related

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