Profile() feature addition (#1673)

utils/torch_utils.py

 # PyTorch utils
 
 import logging
+import math
 import os
 import time
 from contextlib import contextmanager
 from copy import deepcopy
 
-import math
 import torch
 import torch.backends.cudnn as cudnn
 import torch.nn as nn
 import torch.nn.functional as F
 import torchvision
 
+try:
+    import thop  # for FLOPS computation
+except ImportError:
+    thop = None
 logger = logging.getLogger(__name__)
 
 
@@ -66,10 +70,45 @@ def select_device(device='', batch_size=None):
 
 
 def time_synchronized():
+    # pytorch-accurate time
     torch.cuda.synchronize() if torch.cuda.is_available() else None
     return time.time()
 
 
+def profile(x, ops, n=100, device=torch.device('cuda:0' if torch.cuda.is_available() else 'cpu')):
+    # profile a pytorch module or list of modules. Example usage:
+    #     x = torch.randn(16, 3, 640, 640)  # input
+    #     m1 = lambda x: x * torch.sigmoid(x)
+    #     m2 = nn.SiLU()
+    #     profile(x, [m1, m2], n=100)  # profile speed over 100 iterations
+
+    x = x.to(device)
+    x.requires_grad = True
+    print(torch.__version__, device.type, torch.cuda.get_device_properties(0) if device.type == 'cuda' else '')
+    print(f"\n{'Params':>12s}{'FLOPS':>12s}{'forward (ms)':>16s}{'backward (ms)':>16s}{'input':>24s}{'output':>24s}")
+    for m in ops if isinstance(ops, list) else [ops]:
+        m = m.to(device) if hasattr(m, 'to') else m
+        dtf, dtb, t = 0., 0., [0., 0., 0.]  # dt forward, backward
+        try:
+            flops = thop.profile(m, inputs=(x,), verbose=False)[0] / 1E9 * 2  # GFLOPS
+        except:
+            flops = 0
+
+        for _ in range(n):
+            t[0] = time_synchronized()
+            y = m(x)
+            t[1] = time_synchronized()
+            _ = y.sum().backward()
+            t[2] = time_synchronized()
+            dtf += (t[1] - t[0]) * 1000 / n  # ms per op forward
+            dtb += (t[2] - t[1]) * 1000 / n  # ms per op backward
+
+        s_in = tuple(x.shape) if isinstance(x, torch.Tensor) else 'list'
+        s_out = tuple(y.shape) if isinstance(y, torch.Tensor) else 'list'
+        p = sum(list(x.numel() for x in m.parameters())) if isinstance(m, nn.Module) else 0  # parameters
+        print(f'{p:12.4g}{flops:12.4g}{dtf:16.4g}{dtb:16.4g}{str(s_in):>24s}{str(s_out):>24s}')
+
+
 def is_parallel(model):
     return type(model) in (nn.parallel.DataParallel, nn.parallel.DistributedDataParallel)