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AI Hardware: GPUs, TPUs, and NPUs Explained

23 min read

More than 80% of modern machine learning speedups come from using specialized AI processors. This shift has reshaped computing. It lets researchers and engineers train larger models faster while cutting power and cost. The evolution from traditional computing to specialized AI hardware represents a fundamental shift in how we approach machine learning fundamentals.

AI hardware now includes GPUs, TPUs, and NPUs as core options. GPUs brought massive parallelism to graphics and then to neural networks. Googles TPUs followed as application-specific ASICs for tensor math.

NPUs arrived to handle energy-efficient on-device inference for smartphones and IoT. Each class of machine learning accelerators solves limits of CPUs. Choosing between GPUs, TPUs, and NPUs depends on the workload, budget, and deployment.

Training large models favors GPUs or TPUs. Edge inference benefits from NPUs and low-power AI processors.

Key Takeaways

Overview of AI hardware and its importance

The rise of machine learning led to the creation of specialized processors. These processors handle large-scale math more efficiently than general-purpose CPUs. Engineers moved away from just increasing transistor counts.

Graphics cards from NVIDIA showed that offloading heavy matrix work can speed up training. Google then introduced Tensor Processing Units for deep learning tasks. Mobile vendors added neural engines for on-device inference with low power.

Specialized processors improve throughput and reduce latency for demanding models. This is crucial for researchers and product teams. They need fast training and real-time features.

Purpose-built accelerators are designed for neural network math patterns. They use low-precision formats and large matrix units. Memory layouts are also optimized for parallelism.

Designers balance flexibility and power efficiency when creating hardware. GPUs are programmable and offer high throughput for training. TPUs focus on matrix multiply throughput with strong performance-per-watt.

NPUs are great for inference on edge devices. They balance latency and power use for tight thermal budgets.

Evaluations focus on key metrics like samples per second for throughput and milliseconds for latency. Watts per operation measure power efficiency, and total cost assesses cost-efficiency. Teams choose hardware based on these metrics and their workload needs.

Understanding the CPU role in AI systems

The CPU is the heart of the system, launching software and managing data. It prepares data for accelerators like GPUs and TPUs. Its design is great for quick decisions and flexible control, keeping things running smoothly.

CPU strengths: control, sequential tasks, and orchestration

Modern CPUs are excellent at control-plane work. They run the operating system and schedule tasks. This makes them perfect for handling different instructions and unpredictable code paths.

For tasks like tokenization and data munging in NLP, CPUs are the fastest. They’re also great for prototyping and debugging. For more on what CPUs do, check out this CPU glossary entry.

CPU limitations for ML: limited parallelism and memory bottlenecks

CPUs have fewer cores than GPUs, limiting their parallel processing. Instruction overhead and memory access can slow down large tasks. This creates memory bottlenecks in training and inference.

For tasks needing wide data parallelism or constant tensor math, accelerators are better. Memory bandwidth and cache behavior are crucial for feeding many arithmetic units.

Typical AI tasks still suited to CPUs (prototyping, sequential models)

CPUs are good for on-device inference on low-power devices like Raspberry Pi. They handle sequential models and certain preprocessing steps well.

Small-scale experiments, one-shot learning, and tasks needing lots of memory are better on CPUs. Use CPUs for control, versatility, and predictable latency.

What is a GPU and how it accelerates AI workloads

GPUs started as graphics processors but now play a key role in machine learning. They excel at handling large numbers of math operations at once. Modern GPUs have hundreds to thousands of small cores, perfect for neural network training.

GPU architecture

GPU architecture: many small cores and parallel execution

A GPU has many arithmetic units on one chip. Each core does simple tasks, allowing for wide parallel execution. This makes it fast for tasks like processing images or sequences, particularly crucial for training modern transformer architectures that power language models.

Matrix and vector operations: why GPUs excel at deep learning

Deep learning needs matrix multiplication and vector operations. GPUs are great at these because they keep many cores busy with the same task. Even if each core is slower, thousands of them make a big difference.

Software ecosystem: CUDA, cuDNN, and frameworks (TensorFlow, PyTorch)

Just hardware isn’t enough. NVIDIA’s CUDA lets developers program GPUs well. Libraries like cuDNN make convolutions and other operations faster. Frameworks like TensorFlow and PyTorch use these libraries for quick training and inference.

Tools like TensorRT can also improve model performance for deployment. To get the most out of a GPU, developers should design models and data pipelines to match its strengths. This way, the GPU won’t be idle while the CPU waits.

GPU use cases and practical deployment scenarios

GPUs do more than just play games. They handle big data tasks in science, medicine, and image work. NVIDIA and AMD create tools that help labs and big companies train deep learning models fast.

Training large neural networks

For making and testing models, GPUs are key. Using many NVIDIA A100 or H100 cards helps teams work faster. This is crucial for projects in language, medicine, and genetics.

Inference at scale

In production, GPUs handle lots of queries for services. Clouds and on-prem setups run millions of requests hourly. It’s all about smart batching and model tweaks for cost savings.

Practical deployments and mixed workloads

GPUs aren’t just for ML. They’re also used in 3D, video, and finance. Their versatility is great for teams needing different tasks. Many choose GPUs for their all-in-one solution.

Known limitations

GPUs struggle with certain tasks like complex branching. Code that needs to follow a strict order can slow down. Also, big setups need to watch their power use and cooling.

Designing around limits

To overcome these issues, developers use tricks like model pruning and quantization. They also rewrite code to make it more parallel. Choosing the right platform is all about finding a balance between speed, energy, and cost.

What is a TPU and how Tensor Processing Units work

A Tensor Processing Unit is a chip made for neural networks. Google created it to speed up TensorFlow workloads. It focuses on dense tensor operations, not general-purpose tasks.

The heart of a TPU is a grid of matrix multiply units. These units do lots of math at once. They handle most of the work in convolution and transformer tasks.

TPUs are energy-efficient because they use low-precision arithmetic. Formats like bfloat16 or mixed precision are used. This means devices can perform better and use less power.

Software makes TPU work well. TensorFlow models are compiled through XLA. This maps operations to matrix multiply units and on-chip memory. Google Cloud TPU services offer access to TPU pods for large-scale training.

TPUs aren’t just for TensorFlow. Models from PyTorch and JAX can also use TPU architecture. This is thanks to compatible runtimes and cloud services.

AspectWhy it mattersTypical value
Compute elementPerforms bulk tensor math with high parallelismMatrix multiply units array
Data formatBalances precision and throughput for DLLow-precision arithmetic (bfloat16 / mixed)
IntegrationCompiler and software stack map graphs efficientlyXLA with TensorFlow; Google Cloud TPU access
Form factorOptimized ASIC for large-scale deploymentsASIC for AI used in racks and pods

For a quick look at TPU’s history and specs, check out this summary on Tensor Processing Unit.

TPU strengths, weaknesses, and ideal AI applications

TPUs are great for training models quickly and efficiently. They work best with matrix math and low-precision formats. This makes them cost-effective for many tasks. Cloud TPUs let teams access this power, affecting how and when they deploy.

TPU strengths High throughput is key for big models. TPUs are fast at matrix operations and continuous computing. This speeds up training for complex networks. TensorFlow users often see faster results on TPUs.

TPUs are perfect for LLMs and vision tasks. They’re efficient for training large language models. This means research teams can test ideas faster, moving from weeks to months.

Recommendation systems also benefit from TPU speed. They’re great for dense embedding and ranking. This cuts down the time needed to test and improve models.

High throughput and power efficiency

TPUs are more efficient than many accelerators for tensor-heavy tasks. This lowers costs for long-running tasks. It’s a big plus for teams watching their budgets.

Best fits for modern workloads

LLMs, computer vision, and recommendation systems are great for TPUs. They need dense linear algebra and scale well. TensorFlow and XLA optimizations help get the best performance.

Trade-offs and practical constraints

TPUs are not as flexible as GPUs. They’re great for specific tensor operations but struggle with custom code. This can be a problem for research needing quick changes.

Most teams use cloud TPUs, which depends on Google Cloud. This can be a challenge for teams needing on-prem solutions.

CharacteristicTPU AdvantagePractical Impact
ThroughputHigh for matrix opsFaster epochs for LLMs and vision models
Power efficiencyOptimized per wattLower operational cost for long runs
FlexibilityLimited (ASIC)Harder to run custom or non-tensor code
PrecisionLow-to-modest precision favoredAdequate for many ML tasks, not all numerical work
AccessMostly via cloud TPUsDepends on Google Cloud availability and region

When choosing between TPUs and GPUs, consider their strengths and limitations. A good guide is at TPU vs GPU explainer. It helps teams decide when cloud TPUs are best for training and production.

What is an NPU and where NPUs are typically used

The neural processing unit (NPU) is a special chip designed to make neural networks work faster. It focuses on quick data flow for tasks like matrix multiplies and weight fetches. This makes it more efficient than regular chips, using less power and time.

NPU designs aim to make neural inference work well on limited hardware. This lets edge NPUs handle tasks like image recognition, voice commands, and sensor fusion right on the device. No need to send data to the cloud.

On-device AI changes how we use technology by keeping it local. This means faster, more private experiences. Smartphones and IoT devices use it for face unlock, real-time translation, and augmented reality, all with quick responses.

Commercial silicon shows how dedicated chips can make a big difference. Apple’s Neural Engine, for example, powers many iPhone features by taking the load off the CPU and GPU. Qualcomm’s Hexagon and its DSP ecosystem do the same for Android devices.

Edge NPUs are made to be energy-efficient and fast. Designers adjust things like quantization and memory to make them great at repeated tasks. This is perfect for mobile and embedded systems.

NPU strengths and constraints for edge AI

NPUs are great for devices that need quick, local decisions with little power. They use special data paths and weight compression. This helps them do low-power inference fast.

Low-power, low-latency inference for real-time features

Apple and Qualcomm’s architectures are designed for fast tasks. They finish in milliseconds. This makes NPUs perfect for real-time AI on phones and wearables.

Processing on the device cuts down on time to cloud servers. It also boosts privacy for sensitive tasks.

Optimized for inference, not large-scale training

NPUs are made for inference, not training big models. They don’t have enough memory or floating-point power for training like data-center GPUs.

Manufacturers often team NPUs with mobile CPUs and GPUs. This setup handles pre- and post-processing while the NPU runs the main model.

Common applications across constrained devices

Face recognition for secure unlock, voice assistants, and AR applications are common NPU tasks. They need low-power inference and consistent real-time AI.

New trends like federated learning and distributed inference use many NPUs. This improves models without needing a central server.

Comparing GPUs, TPUs, and NPUs: architectures and performance

GPU vs TPU vs NPU

GPUs, TPUs, and NPUs differ in design, affecting how teams choose them for various tasks. Each type aims for a specific balance of speed, latency, and energy use. Knowing about parallelism models, data precision, and performance-per-watt helps pick the right hardware for each task.

Parallelism models vary by architecture. NVIDIA GPUs have thousands of small cores for wide, data-parallel tasks. Google TPUs focus on matrix multiply units for high tensor math efficiency. Apple and Qualcomm’s NPUs use pipeline and systolic-array patterns for fast on-device inference. For more on these designs, see this guide on comparing AI hardware.

Parallelism impacts algorithm choice. GPUs and TPUs are great for data-parallel neural network training. They use thousands of parallel operations. NPUs, on the other hand, use layer-by-layer pipelines and small, quantized kernels for low power and predictable latency.

Data precision formats are key for speed and memory. GPUs support FP32 and FP16 for high-precision training. TPUs use bfloat16 and low-precision math to save memory. NPUs rely on integer quantization, like INT8, to reduce footprint and extend battery life. Reduced precision speeds up inference and cuts bandwidth needs.

Choosing a precision format often requires calibration and retraining. Quantization-aware training or post-training calibration can keep accuracy when moving to lower precision formats.

WorkloadBest fitTypical precisionStrengthCost consideration
Large-scale trainingTPU podsbfloat16, mixedHigh throughput, efficient at scaleHigher cloud spend, lower energy per op
Flexible model developmentGPU farms (NVIDIA)FP32, FP16Developer ecosystem, broad framework supportHardware and power costs vary widely
On-device inferenceNPUs (Apple Neural Engine, Qualcomm)INT8, quantizedLow latency, minimal power drawLower hardware cost per device, software tooling needed

Performance-per-watt is crucial. TPUs are energy-efficient for cloud tensor workloads. GPUs balance flexibility and availability for research and production. NPUs focus on performance-per-watt for battery-powered devices. Real-world costs include hardware, software, and cloud charges.

When comparing GPUs, TPUs, and NPUs, consider parallelism models, data precision, and performance-per-watt. The best choice may be a mix: GPUs for experimentation, TPUs for large-scale training, and NPUs for edge inference. This approach optimizes cost and efficiency.

Choosing the right hardware for AI projects

Choosing the right platform means matching processors to tasks. CPUs are key for tasks like data prep and memory-heavy work. GPUs are great for general training and research. Tensor Processing Units are best for big tensor workloads, like Google Cloud TPU. NPUs are perfect for on-device inference, where speed and power are crucial.

Match processor to workload

For big model training, GPUs or TPUs are top picks. For fast inference near users, NPUs are the way to go. CPUs are best for experimental models and control logic. This simple rule helps in choosing the right hardware.

Factors to weigh

Model size affects memory and interconnect needs. Latency goals decide if inference should be on-device or in a datacenter. Budgets influence choices between upfront costs and cloud expenses. On-prem constraints, hybrid cloud use, and regulations also play a role.

Training vs inference trade-offs

Training focuses on throughput, precision, and scale. Inference prioritizes speed, quantization, and power. Choosing AI hardware involves picking a side and planning for the other when models go to production.

Hybrid AI infrastructure

Most systems use a mix of hardware. A typical setup includes CPUs for orchestration, GPUs or TPUs for training, and NPUs for edge inference. MLOps tools manage these diverse resources and workloads for smooth deployments.

Practical deployment considerations

Test real-world workloads before buying. Look beyond raw performance to end-to-end latency, memory, and power. Consider software ecosystems like CUDA, TensorFlow, or vendor SDKs for long-term support and optimization.

Decision checklist

Software, compilers, and toolchains for AI hardware optimization

Optimizing models for modern accelerators requires a blend of compilers, runtime libraries, and tweaks. AI compilers transform abstract graphs into efficient kernels. These kernels fit the device’s memory and compute layout, reducing latency and boosting throughput on GPUs, TPUs, and NPUs.

Projects like XLA from Google, MLIR for multi-level IR transformations, and Glow from Meta AI are key. They rewrite computation graphs to improve performance. This includes fusing operators, lowering data formats, and scheduling for vector units or matrix cores.

Runtime optimizers and libraries complete the stack. NVIDIA TensorRT and cuDNN offer kernels optimized for GPU architectures. AutoTVM automates finding the best schedule for a device, saving time when moving models between servers and edge devices.

Model-level techniques also play a role. Quantization reduces numeric precision to integers, lowering memory and compute needs. Pruning removes redundant weights, reducing operations and storage.

Other methods like low-rank factorization and knowledge distillation offer accuracy for latency and model size. Combining these with XLA, MLIR, Glow, TensorRT, cuDNN, and AutoTVM creates a co-designed path. This path aligns software with hardware strengths.

LayerRepresentative ToolsPrimary Benefit
Graph compilersXLA, MLIR, GlowOperator fusion and device-tailored lowering
Runtime librariesTensorRT, cuDNNHighly optimized kernels for inference and training
Auto-tuningAutoTVM, TensorRT autotuneFinds optimal schedules and kernel params for hardware
Model optimizationsQuantization, pruning, factorizationReduced memory footprint and lower latency
Co-design strategyCompiler + runtime + model tweaksMaximizes throughput per watt on target accelerators

Edge AI and the growing role of NPUs and on-device inference

Processing data locally changes how products behave and how teams design features. Edge AI moves model execution from cloud centers to phones, cameras, and sensors. This shift relies on NPUs for edge to run neural models efficiently with low power.

On-device inference cuts down on delays to servers. This improves user experiences for camera effects and voice assistants. It also reduces raw data traveling across networks, enhancing privacy for tasks like face recognition.

Designing for small form factors and battery limits requires tough choices. Developers must shrink model size, reduce memory use, and manage thermal profiles. NPUs for edge are designed to balance throughput and energy use, ensuring devices can handle real-time features without overheating.

Distributed approaches are changing training patterns. Federated learning techniques let smartphones train on-device and send updates to a central server. This method lowers data exposure and scales learning across many endpoints, making it practical for large fleets.

System architects combine on-device inference with occasional cloud assistance. Lightweight models run continuously on NPUs, while heavier analytics execute in data centers. This hybrid approach keeps latency low, preserves privacy, and leverages centralized compute where needed.

AspectOn-Device StrengthEdge Constraint
LatencyMilliseconds for interactive tasksMust optimize model pipelines to avoid jitter
PrivacyRaw data stays on-device, reducing exposureSecure storage and update channels required
PowerNPUs for edge deliver high performance per wattBattery budgets limit sustained peak workloads
ScaleFederated learning aggregates many small updatesHeterogeneous hardware complicates model rollout
Use casesLocal voice assistants, AR, biometric unlockLess suited for massive model training

Data center AI: scale, orchestration, and accelerator racks

Big model work goes beyond one server. Today’s data center AI uses racks full of accelerators. These racks share networks, storage, and power. Engineers design them for steady performance in training and inference, keeping costs low.

Accelerator clusters combine many GPUs for fast matrix math. TPU pods offer narrow, high-speed paths for tensor operations. By mixing different accelerators across racks, teams can use the best hardware for each task.

Kubernetes is key in many orchestration systems. It manages containers, schedules tasks, and sets resource limits.

MLOps frameworks work with Kubernetes for model management. They handle versioning, testing, and deployment. These tools help teams manage the whole process, from training to rollout.

Costs influence architecture choices. Cloud providers charge by the hour for TPU pods and GPU instances. They include managed networking and autoscaling. On-prem requires upfront costs for racks and cooling but can be cheaper at scale.

Choosing between cloud and on-prem costs is complex. Cloud speeds up experimentation and handles hardware. On-prem offers control and stable costs for high-use workloads.

Here’s a quick guide to help plan. It shows the main benefits and challenges of each model and accelerator.

DimensionCloud (GPU / TPU)On-Prem Racks
ElasticityHigh: instant scaling of GPU clusters and TPU podsLow to medium: scaling requires hardware procurement
Operational OverheadLow: provider handles maintenance and networkingHigh: staffing for power, cooling, and hardware lifecycle
Unit Cost at ScaleHigher hourly rates; lower upfrontLower per-unit cost over multi-year lifecycle
Time to ExperimentFast: new GPU clusters available in minutesSlower: procurement and rack integration required
Integration with MLOpsNative integrations with hosted MLOps and KubernetesRequires on-prem MLOps stack and Kubernetes tuning
Security and ComplianceStrong options; depends on provider controlsDirect control for sensitive workloads
Best FitVariable demand, quick iteration, proof of conceptSteady, high-utilization training and long-term projects

The world of ML accelerators is changing quickly. Engineers and researchers are working together to make hardware and software better together. This effort helps get more out of specific tasks.

New ways to design hardware and software are leading to better performance. Compilers now understand chip layouts and runtimes manage heat. This results in faster and more efficient work.

Companies like NVIDIA and Google are making tools that work well with special chips. These tools help get the most out of the hardware.

New chip designs are being explored. For example, Intel Loihi uses a unique way to compute that saves power. FPGAs are also popular for their ability to be customized and updated quickly.

Auto-tuning systems are making it easier to get the best performance. Tools like AutoTVM and vendor utilities pick the best settings automatically. This makes it faster to adapt to different hardware.

Meta-accelerators and unified systems aim to make things simpler. They hide the complexity of different hardware behind easy-to-use APIs. This makes it easier to use different chips together.

The table below compares key attributes of emerging accelerators and orchestration approaches.

CategoryStrengthTypical UseIntegration Note
Neuromorphic chipsUltra-low power, event-driven computeSpiking networks, sensing at the edgeRequires specialized stacks and research frameworks
FPGAsHardware-level customization, low latencyRealtime inference, protocol offloadGood for prototyping and production with RTL/IP flows
Auto-tuning frameworksAutomated kernel and parameter selectionOptimizing inference and training kernelsWorks across GPUs, FPGAs, and vendor accelerators
Meta-accelerators / orchestrationUnified scheduling across diverse hardwareHeterogeneous deployments in cloud and edgeRelies on standard APIs and runtime adapters
Hardware-software co-designMaximized domain-specific performanceCustom accelerators for vision, LLMs, and recommendersDemands joint teams and tailored compilers

Conclusion

The world of AI hardware is filled with special engines. CPUs manage tasks, GPUs and TPUs handle big data, and NPUs work on devices. This mix boosts performance, cuts down on delays, and saves energy in different settings.

Teams use software like TensorFlow and PyTorch with these engines. They also use tools like TensorRT and optimize models. This way, they can pick the right tools for their needs, making AI work better in real life.

The future of AI hardware looks bright. It will focus on working together to make better chips and software. New chips and smarter ways to use them will lead to even more progress. For more on this, check out this article on AI hardware and efficiency.

When picking AI hardware, consider what you need to do, where you’ll use it, and the cost over time. Choosing wisely today helps teams stay ahead as technology improves.

FAQ

What is the difference between CPUs, GPUs, TPUs, and NPUs?

CPUs handle general tasks and manage systems. GPUs are great for tasks that need lots of parallel work, like training deep neural networks. TPUs are made by Google for fast tensor and matrix multiplication. NPUs are for fast, energy-saving tasks on devices like smartphones.

Why do AI workloads need specialized processors?

CPUs struggle with AI tasks because they can’t handle lots of work at once. Specialized processors like GPUs and TPUs help by doing tasks in parallel and using less power. This makes AI tasks faster and cheaper.

When should I use a GPU versus a TPU?

Use GPUs for flexible tasks and research. They’re good for many deep-learning models. Choose TPUs for high-speed tensor work, like big language models, on Google Cloud.

Are NPUs useful for production ML?

Yes, NPUs are great for fast, low-power tasks like face recognition on smartphones. They’re not for big training tasks but are key for edge devices.

What metrics matter when evaluating AI hardware?

Look at throughput, latency, energy efficiency, and cost. Also, consider precision formats and software support.

How do precision formats affect hardware choice?

Precision affects speed and memory use. GPUs use FP32 and FP16. TPUs use bfloat16 for speed. NPUs use integer quantization for energy efficiency.

Can I mix different accelerators in one workflow?

Yes, mixing CPUs, GPUs, TPUs, and NPUs is common. CPUs manage tasks, GPUs do training, TPUs handle tensor work, and NPUs do on-device inference.

What software and toolchains optimize performance on accelerators?

Important tools include frameworks, vendor libraries, compilers, and auto-tuning systems. They help map models to hardware and optimize performance.

How do cost and deployment environment influence hardware selection?

Cost and deployment affect choice. Cloud instances offer flexibility, while on-prem racks can save money. Choose based on model size, latency, and budget.

What are the limits of TPUs and NPUs?

TPUs are specialized for tensor math but less flexible. NPUs are good for fast, low-power inference but not for large training. Both need specific software and may limit model choices.

What role do FPGAs and neuromorphic chips play in ML acceleration?

FPGAs offer customizable acceleration. Neuromorphic chips, like Intel Loihi, are for efficient event-driven workloads. They’re key in specific contexts where tailored hardware-software co-design is beneficial.

How do edge constraints shape NPU and model design?

Edge devices have strict power and memory limits. NPUs and optimized models are designed for these constraints. Techniques like federated learning help improve privacy and reduce central compute needs.

Expect closer hardware-software co-design and broader auto-tuning. There will be more unified ecosystems and convergence toward unified hardware. Neuromorphic research, FPGA adoption, and improved compilers are also on the horizon.