What is Time schedule difference? between torch.sigmoid(torch.randn((bs,)) and timesteps[random.randint(0, 999)

[xilanhua12138]

In the file 3139864#diff-dcf224c4e9bbbf1401dce3c8338c64162c858fb21a9e8625e828637896adfcddR255

Why do you change:
t = torch.sigmoid(torch.randn((bs,), device=accelerator.device))
to:
t = torch.tensor([timesteps[random.randint(0, 999)]]).to(accelerator.device)

I found that in the first version, the training time is always near 0.5, and in the second version t has much wider span

[xilanhua12138]

@stazizov, @0xb1b1, @gradient-diffusion