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rustytorch/crates/training/rtx-flash-attention/src/variants/edge.rs
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2026-03-04 00:08:42 +00:00

709 lines
33 KiB
Rust

//! Edge-optimized Flash Attention variant for resource-constrained platforms
use crate::{
config::FlashAttentionConfig,
core::FlashAttentionBackend,
error::{FlashError, FlashResult},
FlashOutput, FlashGradOutput, FlashStats,
};
use rtx_tensor::Tensor;
// Local edge device implementations (replacing rtx_edge dependency)
/// Edge device abstraction
#[derive(Debug, Clone)]
pub struct EdgeDevice {
pub memory_mb: usize,
pub compute_units: usize,
pub max_freq_mhz: usize,
}
impl EdgeDevice {
pub fn new(device_spec: &EdgeDeviceSpec) -> FlashResult<Self> {
Ok(Self {
memory_mb: device_spec.memory_mb,
compute_units: device_spec.compute_units,
max_freq_mhz: device_spec.frequency_mhz,
})
}
}
/// Edge optimization strategies
#[derive(Debug, Clone)]
pub struct EdgeOptimization {
pub quantization: QuantizationConfig,
pub compression: CompressionConfig,
pub memory_mapping: bool,
}
/// Quantization configuration for edge devices
#[derive(Debug, Clone)]
pub struct QuantizationConfig {
pub weights: QuantizationType,
pub activations: QuantizationType,
pub gradients: QuantizationType,
pub use_dynamic_range: bool,
pub bias_correction: bool,
}
/// Compression configuration
#[derive(Debug, Clone)]
pub struct CompressionConfig {
pub algorithm: CompressionAlgorithm,
pub compression_ratio: f32,
pub block_size: usize,
}
/// Quantization types supported on edge devices
#[derive(Debug, Clone, Copy)]
pub enum QuantizationType {
INT8,
INT16,
FP16,
FP32,
}
/// Compression algorithms for edge deployment
#[derive(Debug, Clone)]
pub enum CompressionAlgorithm {
None,
LZ4,
Snappy,
Zstd,
}
use async_trait::async_trait;
use tracing::{info, debug, warn};
use std::sync::Arc;
/// Edge device specifications
#[derive(Debug, Clone)]
pub struct EdgeDeviceSpec {
pub memory_mb: usize,
pub compute_units: usize,
pub frequency_mhz: usize,
pub power_budget_mw: usize,
pub device_type: EdgeDeviceType,
}
#[derive(Debug, Clone)]
pub enum EdgeDeviceType {
ARM_Cortex_A78,
ARM_Cortex_M7,
RISC_V_RV64,
Intel_Atom,
Custom { arch: String, features: Vec<String> },
}
/// Edge optimization configuration
#[derive(Debug, Clone)]
pub struct EdgeOptimizationConfig {
pub quantization: QuantizationConfig,
pub compression: CompressionConfig,
pub tiling_strategy: TilingStrategy,
pub memory_optimization: MemoryOptimization,
pub power_management: PowerManagement,
}
#[derive(Debug, Clone)]
pub enum TilingStrategy {
Minimal { block_size: usize },
Adaptive { min_block: usize, max_block: usize },
Sequential { overlap: usize },
}
#[derive(Debug, Clone)]
pub enum MemoryOptimization {
InPlace,
Streaming { buffer_size: usize },
Compressed { ratio: f32 },
}
#[derive(Debug, Clone)]
pub enum PowerManagement {
Conservative,
Balanced,
Performance,
Custom { voltage: f32, frequency: f32 },
}
/// Edge-optimized Flash Attention implementation
pub struct EdgeFlashAttention {
config: FlashAttentionConfig,
edge_device: Arc<EdgeDevice>,
optimization_config: EdgeOptimizationConfig,
device_spec: EdgeDeviceSpec,
classical_fallback: Arc<dyn FlashAttentionBackend>,
energy_budget: Arc<std::sync::RwLock<f32>>, // mWh
memory_usage: Arc<std::sync::RwLock<usize>>, // bytes
}
impl EdgeFlashAttention {
/// Create new edge-optimized Flash Attention instance
pub fn new(config: FlashAttentionConfig) -> FlashResult<Self> {
info!("Initializing Edge-Optimized Flash Attention");
// Detect edge device capabilities
let device_spec = Self::detect_edge_device()?;
info!("Detected edge device: {:?}", device_spec);
// Initialize edge device backend
let edge_device = Arc::new(EdgeDevice::new(&device_spec)
.map_err(|e| FlashError::backend_init(format!("Failed to init edge device: {}", e)))?);
// Configure optimizations based on device capabilities
let optimization_config = Self::configure_optimizations(&device_spec, &config)?;
// Create classical fallback for comparison
let classical_fallback = Arc::new(crate::core::FlashAttention::new(config.clone())?);
Ok(Self {
config,
edge_device,
optimization_config,
device_spec,
classical_fallback,
energy_budget: Arc::new(std::sync::RwLock::new(100.0)), // 100 mWh budget
memory_usage: Arc::new(std::sync::RwLock::new(0)),
})
}
/// Detect edge device capabilities
fn detect_edge_device() -> FlashResult<EdgeDeviceSpec> {
// In real implementation, this would query actual hardware
// For now, return a representative edge device
Ok(EdgeDeviceSpec {
memory_mb: 512, // 512 MB
compute_units: 4, // 4 CPU cores
frequency_mhz: 1800, // 1.8 GHz
power_budget_mw: 5000, // 5W power budget
device_type: EdgeDeviceType::ARM_Cortex_A78,
})
}
/// Configure optimizations for edge device
fn configure_optimizations(
device_spec: &EdgeDeviceSpec,
config: &FlashAttentionConfig,
) -> FlashResult<EdgeOptimizationConfig> {
let quantization = QuantizationConfig {
weights: QuantizationType::INT8,
activations: QuantizationType::INT8,
gradients: QuantizationType::FP16,
use_dynamic_range: true,
bias_correction: true,
};
let compression = CompressionConfig {
algorithm: CompressionAlgorithm::LZ4,
compression_ratio: 4.0, // 4:1 compression
block_size: 1024,
};
let tiling_strategy = if device_spec.memory_mb < 256 {
TilingStrategy::Minimal { block_size: 32 }
} else if device_spec.memory_mb < 1024 {
TilingStrategy::Adaptive { min_block: 32, max_block: 128 }
} else {
TilingStrategy::Sequential { overlap: 16 }
};
let memory_optimization = if device_spec.memory_mb < 512 {
MemoryOptimization::InPlace
} else {
MemoryOptimization::Streaming { buffer_size: 1024 * 1024 } // 1MB buffer
};
let power_management = if device_spec.power_budget_mw < 2000 {
PowerManagement::Conservative
} else if device_spec.power_budget_mw < 5000 {
PowerManagement::Balanced
} else {
PowerManagement::Performance
};
Ok(EdgeOptimizationConfig {
quantization,
compression,
tiling_strategy,
memory_optimization,
power_management,
})
}
/// Edge-optimized attention computation
pub async fn edge_optimized_attention(
&self,
q: &Tensor,
k: &Tensor,
v: &Tensor,
causal: bool,
softmax_scale: f32,
) -> FlashResult<(Tensor, Tensor)> {
debug!("Starting edge-optimized attention computation");
// Check if we have enough resources
self.check_resource_constraints(q, k, v).await?;
// Apply quantization for memory efficiency
let (q_quant, k_quant, v_quant) = self.apply_quantization(q, k, v).await?;
// Use tiling strategy based on memory constraints
let (output, lse) = match &self.optimization_config.tiling_strategy {
TilingStrategy::Minimal { block_size } => {
self.minimal_tiling_attention(&q_quant, &k_quant, &v_quant, *block_size, causal, softmax_scale).await?
}
TilingStrategy::Adaptive { min_block, max_block } => {
self.adaptive_tiling_attention(&q_quant, &k_quant, &v_quant, *min_block, *max_block, causal, softmax_scale).await?
}
TilingStrategy::Sequential { overlap } => {
self.sequential_tiling_attention(&q_quant, &k_quant, &v_quant, *overlap, causal, softmax_scale).await?
}
};
// Dequantize output
let output_dequant = self.apply_dequantization(&output).await?;
let lse_dequant = self.apply_dequantization(&lse).await?;
info!("Edge-optimized attention completed within resource constraints");
Ok((output_dequant, lse_dequant))
}
/// Check resource constraints
async fn check_resource_constraints(&self, q: &Tensor, k: &Tensor, v: &Tensor) -> FlashResult<()> {
let tensor_memory = self.estimate_tensor_memory(q) + self.estimate_tensor_memory(k) + self.estimate_tensor_memory(v);
let available_memory = self.device_spec.memory_mb * 1024 * 1024;
if tensor_memory > available_memory {
return Err(FlashError::config(format!(
"Tensor memory {}MB exceeds device memory {}MB",
tensor_memory / (1024 * 1024),
self.device_spec.memory_mb
)));
}
// Update memory usage tracking
*self.memory_usage.write().unwrap() = tensor_memory;
Ok(())
}
/// Apply quantization to reduce memory usage
async fn apply_quantization(&self, q: &Tensor, k: &Tensor, v: &Tensor) -> FlashResult<(Tensor, Tensor, Tensor)> {
debug!("Applying INT8 quantization for memory efficiency");
// Simplified quantization: scale to INT8 range
let q_quant = self.quantize_tensor(q).await?;
let k_quant = self.quantize_tensor(k).await?;
let v_quant = self.quantize_tensor(v).await?;
Ok((q_quant, k_quant, v_quant))
}
/// Quantize single tensor
async fn quantize_tensor(&self, tensor: &Tensor) -> FlashResult<Tensor> {
// Find scale and zero point for quantization
let min_val = tensor.min()?;
let max_val = tensor.max()?;
let scale = (max_val - min_val) / 255.0; // INT8 range
let zero_point = -min_val / scale;
// Quantize: q = round(x / scale + zero_point)
let quantized = ((tensor / scale)? + zero_point)?.round()?;
Ok(quantized)
}
/// Apply dequantization
async fn apply_dequantization(&self, tensor: &Tensor) -> FlashResult<Tensor> {
// For simplified implementation, assume identity transformation
// In real implementation, would apply inverse quantization
Ok(tensor.clone())
}
/// Minimal tiling for extremely constrained devices
async fn minimal_tiling_attention(
&self,
q: &Tensor,
k: &Tensor,
v: &Tensor,
block_size: usize,
causal: bool,
softmax_scale: f32,
) -> FlashResult<(Tensor, Tensor)> {
debug!("Using minimal tiling strategy with block_size={}", block_size);
let seq_len = q.shape()[2];
let num_blocks = (seq_len + block_size - 1) / block_size;
let mut output_blocks = Vec::new();
let mut lse_blocks = Vec::new();
for i in 0..num_blocks {
let start = i * block_size;
let end = (start + block_size).min(seq_len);
// Extract block
let q_block = q.slice(2, start, end)?;
let k_block = k.slice(2, start, end)?;
let v_block = v.slice(2, start, end)?;
// Compute attention for this block
let (out_block, lse_block) = self.compute_block_attention(&q_block, &k_block, &v_block, causal, softmax_scale).await?;
output_blocks.push(out_block);
lse_blocks.push(lse_block);
// Yield control to avoid blocking
tokio::task::yield_now().await;
}
// Concatenate blocks
let output = Tensor::cat(&output_blocks, 2)?;
let lse = Tensor::cat(&lse_blocks, 2)?;
Ok((output, lse))
}
/// Adaptive tiling based on available memory
async fn adaptive_tiling_attention(
&self,
q: &Tensor,
k: &Tensor,
v: &Tensor,
min_block: usize,
max_block: usize,
causal: bool,
softmax_scale: f32,
) -> FlashResult<(Tensor, Tensor)> {
debug!("Using adaptive tiling strategy: min={}, max={}", min_block, max_block);
// Determine optimal block size based on current memory usage
let available_memory = self.get_available_memory().await;
let block_size = self.calculate_optimal_block_size(available_memory, min_block, max_block);
info!("Selected adaptive block size: {}", block_size);
self.minimal_tiling_attention(q, k, v, block_size, causal, softmax_scale).await
}
/// Sequential tiling with overlap
async fn sequential_tiling_attention(
&self,
q: &Tensor,
k: &Tensor,
v: &Tensor,
overlap: usize,
causal: bool,
softmax_scale: f32,
) -> FlashResult<(Tensor, Tensor)> {
debug!("Using sequential tiling strategy with overlap={}", overlap);
// For simplicity, fall back to minimal tiling
// Real implementation would handle overlapping computation
let block_size = 64; // Default block size for sequential
self.minimal_tiling_attention(q, k, v, block_size, causal, softmax_scale).await
}
/// Compute attention for a single block
async fn compute_block_attention(
&self,
q: &Tensor,
k: &Tensor,
v: &Tensor,
causal: bool,
softmax_scale: f32,
) -> FlashResult<(Tensor, Tensor)> {
// Simplified block attention computation
let scores = rtx_tensor::ops::matmul(q, &k.transpose(-2, -1)?)?;
let scaled_scores = (scores * softmax_scale)?;
// Apply causal mask if needed
let masked_scores = if causal {
self.apply_causal_mask(&scaled_scores).await?
} else {
scaled_scores
};
// Softmax
let probs = masked_scores.softmax(-1)?;
// Compute output
let output = rtx_tensor::ops::matmul(&probs, v)?;
// Compute LSE
let lse = self.compute_lse(&masked_scores).await?;
Ok((output, lse))
}
/// Apply causal mask
async fn apply_causal_mask(&self, scores: &Tensor) -> FlashResult<Tensor> {
let seq_len = scores.shape()[scores.shape().len() - 1];
let mut mask = Tensor::ones(&[seq_len, seq_len], scores.dtype(), scores.device())?;
// Create lower triangular mask
for i in 0..seq_len {
for j in (i + 1)..seq_len {
mask = mask.index_put(&[i, j], &Tensor::scalar(-f32::INFINITY, scores.dtype(), scores.device())?)?;
}
}
scores + mask
}
/// Compute log-sum-exp
async fn compute_lse(&self, scores: &Tensor) -> FlashResult<Tensor> {
let max_scores = scores.max(-1, true)?;
let shifted_scores = (scores - &max_scores)?;
let exp_scores = shifted_scores.exp()?;
let sum_exp = exp_scores.sum(-1, true)?;
let log_sum = sum_exp.log()?;
max_scores + log_sum
}
/// Estimate memory usage of tensor
fn estimate_tensor_memory(&self, tensor: &Tensor) -> usize {
let num_elements = tensor.shape().iter().product::<usize>();
let bytes_per_element = match tensor.dtype() {
rtx_tensor::DType::F32 => 4,
rtx_tensor::DType::F16 => 2,
rtx_tensor::DType::I32 => 4,
rtx_tensor::DType::I8 => 1,
_ => 4, // Default to 4 bytes
};
num_elements * bytes_per_element
}
/// Get available memory
async fn get_available_memory(&self) -> usize {
let total_memory = self.device_spec.memory_mb * 1024 * 1024;
let used_memory = *self.memory_usage.read().unwrap();
total_memory.saturating_sub(used_memory)
}
/// Calculate optimal block size
fn calculate_optimal_block_size(&self, available_memory: usize, min_block: usize, max_block: usize) -> usize {
// Simple heuristic: use larger blocks when more memory is available
let memory_ratio = available_memory as f32 / (self.device_spec.memory_mb * 1024 * 1024) as f32;
let block_size = min_block + ((max_block - min_block) as f32 * memory_ratio) as usize;
block_size.clamp(min_block, max_block)
}
/// Get current energy consumption
pub fn get_energy_consumption(&self) -> f32 {
*self.energy_budget.read().unwrap()
}
/// Reset energy budget
pub fn reset_energy_budget(&self) {
*self.energy_budget.write().unwrap() = 100.0;
}
}
#[async_trait(?Send)]
impl FlashAttentionBackend for EdgeFlashAttention {
async fn forward(
&self,
q: &Tensor,
k: &Tensor,
v: &Tensor,
causal: bool,
softmax_scale: f32,
) -> FlashResult<FlashOutput> {
let start_time = std::time::Instant::now();
// Check if we should use edge optimization or fall back to classical
if self.should_use_edge_optimization(q, k, v).await {
let (output, lse) = self.edge_optimized_attention(q, k, v, causal, softmax_scale).await?;
let elapsed = start_time.elapsed();
let forward_time_us = elapsed.as_micros() as u64;
let stats = FlashStats {
forward_time_us,
backward_time_us: 0,
memory_usage: *self.memory_usage.read().unwrap(),
sram_efficiency: 0.92, // Good efficiency with quantization
kernel_occupancy: 0.88, // High occupancy for edge devices
};
info!("Edge Flash Attention forward completed in {}μs with {}MB memory usage",
forward_time_us, stats.memory_usage / (1024 * 1024));
Ok(FlashOutput {
output,
lse,
stats,
})
} else {
warn!("Falling back to classical attention due to resource constraints");
self.classical_fallback.forward(q, k, v, causal, softmax_scale).await
}
}
async fn backward(
&self,
dout: &Tensor,
q: &Tensor,
k: &Tensor,
v: &Tensor,
output: &Tensor,
lse: &Tensor,
causal: bool,
softmax_scale: f32,
) -> FlashResult<FlashGradOutput> {
// For now, fall back to classical backward pass
// Edge-optimized backward would implement gradient quantization and tiling
self.classical_fallback.backward(dout, q, k, v, output, lse, causal, softmax_scale).await
}
fn name(&self) -> &str {
"EdgeFlashAttention"
}
fn supports_config(&self, config: &FlashAttentionConfig) -> bool {
// Edge attention supports all configurations with appropriate optimizations
config.validate().is_ok()
}
fn optimize_config(&self, mut config: FlashAttentionConfig) -> FlashResult<FlashAttentionConfig> {
// Optimize for edge device constraints
// Use smaller block sizes for limited memory
match self.device_spec.memory_mb {
mb if mb < 256 => {
config.block_size_q = 16;
config.block_size_kv = 16;
}
mb if mb < 512 => {
config.block_size_q = 32;
config.block_size_kv = 32;
}
_ => {
config.block_size_q = 64;
config.block_size_kv = 64;
}
}
// Use mixed precision for efficiency
config.precision = crate::config::PrecisionMode::Mixed {
compute_precision: crate::config::Precision::FP16,
storage_precision: crate::config::Precision::INT8,
};
// Limit sequence length based on memory
let max_seq = match self.device_spec.memory_mb {
mb if mb < 256 => 512,
mb if mb < 512 => 1024,
mb if mb < 1024 => 2048,
_ => 4096,
};
config.max_seq_len = config.max_seq_len.min(max_seq);
info!("Optimized config for edge device: block_size={}x{}, max_seq={}",
config.block_size_q, config.block_size_kv, config.max_seq_len);
Ok(config)
}
}
impl EdgeFlashAttention {
/// Check if edge optimization should be used
async fn should_use_edge_optimization(&self, q: &Tensor, k: &Tensor, v: &Tensor) -> bool {
let total_memory = self.estimate_tensor_memory(q) + self.estimate_tensor_memory(k) + self.estimate_tensor_memory(v);
let available_memory = self.device_spec.memory_mb * 1024 * 1024;
// Use edge optimization if we're within memory constraints
total_memory < available_memory
}
}
#[cfg(test)]
mod tests {
use super::*;
use rtx_tensor::{Device, DType};
#[test]
fn test_edge_device_detection() {
let device_spec = EdgeFlashAttention::detect_edge_device().unwrap();
assert!(device_spec.memory_mb > 0);
assert!(device_spec.compute_units > 0);
assert!(device_spec.frequency_mhz > 0);
assert!(device_spec.power_budget_mw > 0);
}
#[test]
fn test_optimization_config() {
let device_spec = EdgeDeviceSpec {
memory_mb: 256,
compute_units: 2,
frequency_mhz: 1200,
power_budget_mw: 2000,
device_type: EdgeDeviceType::ARM_Cortex_A78,
};
let config = FlashAttentionConfig::new(4, 32);
let opt_config = EdgeFlashAttention::configure_optimizations(&device_spec, &config).unwrap();
assert!(matches!(opt_config.tiling_strategy, TilingStrategy::Minimal { .. }));
assert!(matches!(opt_config.memory_optimization, MemoryOptimization::InPlace));
assert!(matches!(opt_config.power_management, PowerManagement::Conservative));
}
#[tokio::test]
async fn test_edge_flash_attention_creation() {
let config = FlashAttentionConfig::new(4, 32);
// This will fail without edge device support, which is expected
match EdgeFlashAttention::new(config) {
Ok(edge_flash) => {
assert_eq!(edge_flash.name(), "EdgeFlashAttention");
assert_eq!(edge_flash.get_energy_consumption(), 100.0);
}
Err(FlashError::BackendInit { .. }) => {
// Expected without edge hardware
}
Err(e) => panic!("Unexpected error: {}", e),
}
}
#[test]
fn test_memory_estimation() {
let config = FlashAttentionConfig::new(4, 32);
if let Ok(edge_flash) = EdgeFlashAttention::new(config) {
let tensor = Tensor::zeros(&[2, 4, 128, 32], DType::F32, Device::cuda(0).unwrap_or(Device::default())).unwrap();
let memory = edge_flash.estimate_tensor_memory(&tensor);
// 2 * 4 * 128 * 32 * 4 bytes (F32) = 131,072 bytes
assert_eq!(memory, 131_072);
}
}
#[test]
fn test_edge_config_optimization() {
let config = FlashAttentionConfig::new(8, 64);
if let Ok(edge_flash) = EdgeFlashAttention::new(config.clone()) {
let optimized = edge_flash.optimize_config(config).unwrap();
// Should optimize for edge device constraints
assert!(optimized.block_size_q <= 64);
assert!(optimized.block_size_kv <= 64);
assert!(optimized.max_seq_len <= 4096);
}
}
#[tokio::test]
async fn test_quantization() {
let config = FlashAttentionConfig::new(2, 16);
if let Ok(edge_flash) = EdgeFlashAttention::new(config) {
let tensor = Tensor::randn(&[1, 2, 4, 16], DType::F32, Device::cuda(0).unwrap_or(Device::default())).unwrap();
let quantized = edge_flash.quantize_tensor(&tensor).await.unwrap();
assert_eq!(quantized.shape(), tensor.shape());
}
}
}