feat(gds): implement GPUDirect Storage for efficient model loading

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Maifee Ul Asad 2025-10-08 14:38:49 +06:00
parent fab0954077
commit 5f24eb699c

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comfy/gds_loader.py Normal file
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# copyright 2025 Maifee Ul Asad @ github.com/maifeeulasad
# copyright under GNU GENERAL PUBLIC LICENSE, Version 3, 29 June 2007
"""
GPUDirect Storage (GDS) Integration for ComfyUI
Direct SSD-to-GPU model loading without RAM/CPU bottlenecks
Still there will be some CPU/RAM usage, mostly for safetensors parsing and small buffers.
This module provides GPUDirect Storage functionality to load models directly
from NVMe SSDs to GPU memory, bypassing system RAM and CPU.
"""
import os
import logging
import torch
import time
from typing import Optional, Dict, Any, Union
from pathlib import Path
import safetensors
import gc
import mmap
from dataclasses import dataclass
try:
import cupy
import cupy.cuda.runtime as cuda_runtime
CUPY_AVAILABLE = True
except ImportError:
CUPY_AVAILABLE = False
logging.warning("CuPy not available. GDS will use fallback mode.")
try:
import cudf # RAPIDS for GPU dataframes
RAPIDS_AVAILABLE = True
except ImportError:
RAPIDS_AVAILABLE = False
try:
import pynvml
pynvml.nvmlInit()
NVML_AVAILABLE = True
except ImportError:
NVML_AVAILABLE = False
logging.warning("NVIDIA-ML-Py not available. GPU monitoring disabled.")
@dataclass
class GDSConfig:
"""Configuration for GPUDirect Storage"""
enabled: bool = True
min_file_size_mb: int = 100 # Only use GDS for files larger than this
chunk_size_mb: int = 64 # Size of chunks to transfer
use_pinned_memory: bool = True
prefetch_enabled: bool = True
compression_aware: bool = True
max_concurrent_streams: int = 4
fallback_to_cpu: bool = True
class GDSError(Exception):
"""GDS-specific errors"""
pass
class GPUDirectStorage:
"""
GPUDirect Storage implementation for ComfyUI
Enables direct SSD-to-GPU transfers for model loading
"""
def __init__(self, config: Optional[GDSConfig] = None):
self.config = config or GDSConfig()
self.device = torch.cuda.current_device() if torch.cuda.is_available() else None
self.cuda_streams = []
self.pinned_buffers = {}
self.stats = {
'gds_loads': 0,
'fallback_loads': 0,
'total_bytes_gds': 0,
'total_time_gds': 0.0,
'avg_bandwidth_gbps': 0.0
}
# Initialize GDS if available
self._gds_available = self._check_gds_availability()
if self._gds_available:
self._init_gds()
else:
logging.warning("GDS not available, using fallback methods")
def _check_gds_availability(self) -> bool:
"""Check if GDS is available on the system"""
if not torch.cuda.is_available():
return False
if not CUPY_AVAILABLE:
return False
# Check for GPUDirect Storage support
try:
# Check CUDA version (GDS requires CUDA 11.4+)
cuda_version = torch.version.cuda
if cuda_version:
major, minor = map(int, cuda_version.split('.')[:2])
if major < 11 or (major == 11 and minor < 4):
logging.warning(f"CUDA {cuda_version} detected. GDS requires CUDA 11.4+")
return False
# Check if cuFile is available (part of CUDA toolkit)
try:
import cupy.cuda.cufile as cufile
# Try to initialize cuFile
cufile.initialize()
return True
except (ImportError, RuntimeError) as e:
logging.warning(f"cuFile not available: {e}")
return False
except Exception as e:
logging.warning(f"GDS availability check failed: {e}")
return False
def _init_gds(self):
"""Initialize GDS resources"""
try:
# Create CUDA streams for async operations
for i in range(self.config.max_concurrent_streams):
stream = torch.cuda.Stream()
self.cuda_streams.append(stream)
# Pre-allocate pinned memory buffers
if self.config.use_pinned_memory:
self._allocate_pinned_buffers()
logging.info(f"GDS initialized with {len(self.cuda_streams)} streams")
except Exception as e:
logging.error(f"Failed to initialize GDS: {e}")
self._gds_available = False
def _allocate_pinned_buffers(self):
"""Pre-allocate pinned memory buffers for staging"""
try:
# Allocate buffers of different sizes
buffer_sizes = [16, 32, 64, 128, 256] # MB
for size_mb in buffer_sizes:
size_bytes = size_mb * 1024 * 1024
# Allocate pinned memory using CuPy
if CUPY_AVAILABLE:
buffer = cupy.cuda.alloc_pinned_memory(size_bytes)
self.pinned_buffers[size_mb] = buffer
except Exception as e:
logging.warning(f"Failed to allocate pinned buffers: {e}")
def _get_file_size(self, file_path: str) -> int:
"""Get file size in bytes"""
return os.path.getsize(file_path)
def _should_use_gds(self, file_path: str) -> bool:
"""Determine if GDS should be used for this file"""
if not self._gds_available or not self.config.enabled:
return False
file_size_mb = self._get_file_size(file_path) / (1024 * 1024)
return file_size_mb >= self.config.min_file_size_mb
def _load_with_gds(self, file_path: str) -> Dict[str, torch.Tensor]:
"""Load model using GPUDirect Storage"""
start_time = time.time()
try:
if file_path.lower().endswith(('.safetensors', '.sft')):
return self._load_safetensors_gds(file_path)
else:
return self._load_pytorch_gds(file_path)
except Exception as e:
logging.error(f"GDS loading failed for {file_path}: {e}")
if self.config.fallback_to_cpu:
logging.info("Falling back to CPU loading")
self.stats['fallback_loads'] += 1
return self._load_fallback(file_path)
else:
raise GDSError(f"GDS loading failed: {e}")
finally:
load_time = time.time() - start_time
self.stats['total_time_gds'] += load_time
def _load_safetensors_gds(self, file_path: str) -> Dict[str, torch.Tensor]:
"""Load safetensors file using GDS"""
try:
import cupy.cuda.cufile as cufile
# Open file with cuFile for direct GPU loading
with cufile.CuFileManager() as manager:
# Memory-map the file for efficient access
with open(file_path, 'rb') as f:
# Use mmap for large files
with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as mmapped_file:
# Parse safetensors header
header_size = int.from_bytes(mmapped_file[:8], 'little')
header_bytes = mmapped_file[8:8+header_size]
import json
header = json.loads(header_bytes.decode('utf-8'))
# Load tensors directly to GPU
tensors = {}
data_offset = 8 + header_size
for name, info in header.items():
if name == "__metadata__":
continue
dtype_map = {
'F32': torch.float32,
'F16': torch.float16,
'BF16': torch.bfloat16,
'I8': torch.int8,
'I16': torch.int16,
'I32': torch.int32,
'I64': torch.int64,
'U8': torch.uint8,
}
dtype = dtype_map.get(info['dtype'], torch.float32)
shape = info['shape']
start_offset = data_offset + info['data_offsets'][0]
end_offset = data_offset + info['data_offsets'][1]
# Direct GPU allocation
tensor = torch.empty(shape, dtype=dtype, device=f'cuda:{self.device}')
# Use cuFile for direct transfer
tensor_bytes = end_offset - start_offset
# Get GPU memory pointer
gpu_ptr = tensor.data_ptr()
# Direct file-to-GPU transfer
cufile.copy_from_file(
gpu_ptr,
mmapped_file[start_offset:end_offset],
tensor_bytes
)
tensors[name] = tensor
self.stats['gds_loads'] += 1
self.stats['total_bytes_gds'] += self._get_file_size(file_path)
return tensors
except Exception as e:
logging.error(f"GDS safetensors loading failed: {e}")
raise
def _load_pytorch_gds(self, file_path: str) -> Dict[str, torch.Tensor]:
"""Load PyTorch file using GDS with staging"""
try:
# For PyTorch files, we need to use a staging approach
# since torch.load doesn't support direct GPU loading
# Load to pinned memory first
with open(file_path, 'rb') as f:
file_size = self._get_file_size(file_path)
# Choose appropriate buffer or allocate new one
buffer_size_mb = min(256, max(64, file_size // (1024 * 1024)))
if buffer_size_mb in self.pinned_buffers:
pinned_buffer = self.pinned_buffers[buffer_size_mb]
else:
# Allocate temporary pinned buffer
pinned_buffer = cupy.cuda.alloc_pinned_memory(file_size)
# Read file to pinned memory
f.readinto(pinned_buffer)
# Use torch.load with map_location to specific GPU
# This will be faster due to pinned memory
state_dict = torch.load(
f,
map_location=f'cuda:{self.device}',
weights_only=True
)
self.stats['gds_loads'] += 1
self.stats['total_bytes_gds'] += file_size
return state_dict
except Exception as e:
logging.error(f"GDS PyTorch loading failed: {e}")
raise
def _load_fallback(self, file_path: str) -> Dict[str, torch.Tensor]:
"""Fallback loading method using standard approaches"""
if file_path.lower().endswith(('.safetensors', '.sft')):
# Use safetensors with device parameter
with safetensors.safe_open(file_path, framework="pt", device=f'cuda:{self.device}') as f:
return {k: f.get_tensor(k) for k in f.keys()}
else:
# Standard PyTorch loading
return torch.load(file_path, map_location=f'cuda:{self.device}', weights_only=True)
def load_model(self, file_path: str, device: Optional[torch.device] = None) -> Dict[str, torch.Tensor]:
"""
Main entry point for loading models with GDS
Args:
file_path: Path to the model file
device: Target device (if None, uses current CUDA device)
Returns:
Dictionary of tensors loaded directly to GPU
"""
if device is not None and device.type == 'cuda':
self.device = device.index or 0
if self._should_use_gds(file_path):
logging.info(f"Loading {file_path} with GDS")
return self._load_with_gds(file_path)
else:
logging.info(f"Loading {file_path} with standard method")
self.stats['fallback_loads'] += 1
return self._load_fallback(file_path)
def prefetch_model(self, file_path: str) -> bool:
"""
Prefetch model to GPU memory cache (if supported)
Args:
file_path: Path to the model file
Returns:
True if prefetch was successful
"""
if not self.config.prefetch_enabled or not self._gds_available:
return False
try:
# Basic prefetch implementation
# This would ideally use NVIDIA's GPUDirect Storage API
# to warm up the storage cache
file_size = self._get_file_size(file_path)
logging.info(f"Prefetching {file_path} ({file_size // (1024*1024)} MB)")
# Read file metadata to warm caches
with open(file_path, 'rb') as f:
# Read first and last chunks to trigger prefetch
f.read(1024 * 1024) # First 1MB
f.seek(-min(1024 * 1024, file_size), 2) # Last 1MB
f.read()
return True
except Exception as e:
logging.warning(f"Prefetch failed for {file_path}: {e}")
return False
def get_stats(self) -> Dict[str, Any]:
"""Get loading statistics"""
total_loads = self.stats['gds_loads'] + self.stats['fallback_loads']
if self.stats['total_time_gds'] > 0 and self.stats['total_bytes_gds'] > 0:
bandwidth_gbps = (self.stats['total_bytes_gds'] / (1024**3)) / self.stats['total_time_gds']
self.stats['avg_bandwidth_gbps'] = bandwidth_gbps
return {
**self.stats,
'total_loads': total_loads,
'gds_usage_percent': (self.stats['gds_loads'] / max(1, total_loads)) * 100,
'gds_available': self._gds_available,
'config': self.config.__dict__
}
def cleanup(self):
"""Clean up GDS resources"""
try:
# Clear CUDA streams
for stream in self.cuda_streams:
stream.synchronize()
self.cuda_streams.clear()
# Free pinned buffers
for buffer in self.pinned_buffers.values():
if CUPY_AVAILABLE:
cupy.cuda.free_pinned_memory(buffer)
self.pinned_buffers.clear()
# Force garbage collection
gc.collect()
torch.cuda.empty_cache()
except Exception as e:
logging.warning(f"GDS cleanup failed: {e}")
def __del__(self):
"""Destructor to ensure cleanup"""
self.cleanup()
# Global GDS instance
_gds_instance: Optional[GPUDirectStorage] = None
def get_gds_instance(config: Optional[GDSConfig] = None) -> GPUDirectStorage:
"""Get or create the global GDS instance"""
global _gds_instance
if _gds_instance is None:
_gds_instance = GPUDirectStorage(config)
return _gds_instance
def load_torch_file_gds(ckpt: str, safe_load: bool = False, device: Optional[torch.device] = None) -> Dict[str, torch.Tensor]:
"""
GDS-enabled replacement for comfy.utils.load_torch_file
Args:
ckpt: Path to checkpoint file
safe_load: Whether to use safe loading (for compatibility)
device: Target device
Returns:
Dictionary of loaded tensors
"""
gds = get_gds_instance()
try:
# Load with GDS
return gds.load_model(ckpt, device)
except Exception as e:
logging.error(f"GDS loading failed, falling back to standard method: {e}")
# Fallback to original method
import comfy.utils
return comfy.utils.load_torch_file(ckpt, safe_load=safe_load, device=device)
def prefetch_model_gds(file_path: str) -> bool:
"""Prefetch model for faster loading"""
gds = get_gds_instance()
return gds.prefetch_model(file_path)
def get_gds_stats() -> Dict[str, Any]:
"""Get GDS statistics"""
gds = get_gds_instance()
return gds.get_stats()
def configure_gds(config: GDSConfig):
"""Configure GDS settings"""
global _gds_instance
_gds_instance = GPUDirectStorage(config)