torch.is_cpu_only_mode

function is_cpu_only_mode(): boolean

Checks if the current environment is operating in CPU-only mode.

Returns true if WebGPU initialization was attempted but failed, indicating that torch.js is running entirely on CPU without GPU acceleration. Returns false if WebGPU is available and initialized successfully.

When This is True:

Browser doesn't support WebGPU (Safari <18, old Chrome, IE, Firefox without flag)
WebGPU initialization failed for some reason (driver issue, hardware issue)
torch.init() completed and detected no GPU support

Performance Implications:

CPU operations are generally 10-100x slower than GPU
Should use smaller batches, models, and datasets
Some operations may not be implemented on CPU

Use Cases:

Adapt batch sizes to available hardware
Skip GPU-specific optimizations
Provide helpful error messages to users
Fallback to alternative algorithms

Binary check: Simpler than is_webgpu_available() for common case
After init: Call after torch.init() for accurate result
Performance critical: Often used to optimize batch size or model complexity
True only if failed: True only if WebGPU was attempted and failed

Null handling: Before torch.init(), result is effectively false
Performance: CPU operations are very slow - plan accordingly
Limited fallbacks: Not all operations have CPU implementations

Returns

boolean– true if in CPU-only mode (WebGPU unavailable), false otherwise

Examples

// Initialize and check CPU-only mode
await torch.init();

if (torch.is_cpu_only_mode()) {
  console.warn('⚠️ Running in CPU-only mode - expect slower performance');
  // Reduce workload for CPU
  const batch_size = 8;
  const model_size = 'small';  // Use smaller model
} else {
  console.log('✓ GPU acceleration enabled');
  // Can use larger workloads
  const batch_size = 128;
  const model_size = 'large';
}

// Conditional algorithm selection
if (torch.is_cpu_only_mode()) {
  // Use faster but less accurate algorithm
  const result = fastApproximation(input);
} else {
  // Use more accurate GPU algorithm
  const result = accurateComputation(input);
}

// Performance warning for users
if (torch.is_cpu_only_mode()) {
  alert('WebGPU not supported in your browser. ' +
        'Please upgrade to Chrome 113+ or Safari 18+ for GPU acceleration.');
}

// Batch size tuning
const maxBatchSize = torch.is_cpu_only_mode() ? 16 : 256;
for (let i = 0; i < dataset.length; i += maxBatchSize) {
  const batch = dataset.slice(i, i + maxBatchSize);
  trainStep(batch);
}

// Combined with device checks
if (!torch.is_cpu_only_mode() && torch.get_default_device() === 'webgpu') {
  console.log('GPU acceleration fully active');
}

torch.is_cpu_only_mode

Returns

Examples

See Also

torch.is_cpu_only_mode

Returns

Examples

See Also