Putting all the tensors on one device
I am using ViViT in my model. Although I moved the input and the my whole model to the cuda, the train process shows an error in the line of position embedding:
class ViViTBackbone(nn.Module):
    &quot;&quot;&quot; Model-3 backbone of ViViT &quot;&quot;&quot;

    def __init__(self, t, h, w, patch_t, patch_h, patch_w, num_classes, dim, depth, heads, mlp_dim, dim_head=3,
                 channels=3, mode='tubelet', emb_dropout=0., dropout=0., model=3):
        super().__init__()

        assert t % patch_t == 0 and h % patch_h == 0 and w % patch_w == 0, &quot;Video dimensions should be divisible by &quot; \
                                                                           &quot;tubelet size &quot;

        self.T = t
        self.H = h
        self.W = w
        self.channels = channels
        self.t = patch_t
        self.h = patch_h
        self.w = patch_w
        self.mode = mode

        self.nt = self.T // self.t
        self.nh = self.H // self.h
        self.nw = self.W // self.w

        tubelet_dim = self.t * self.h * self.w * channels

        self.to_tubelet_embedding = nn.Sequential(
            Rearrange('b c (t pt) (h ph) (w pw) -&gt; b t (h w) (pt ph pw c)', pt=self.t, ph=self.h, pw=self.w),
            nn.Linear(tubelet_dim, dim)
        )

        # repeat same spatial position encoding temporally
        self.pos_embedding = nn.Parameter(torch.randn(1, 1, self.nh * self.nw, dim)).repeat(1, self.nt, 1, 1)

        self.dropout = nn.Dropout(emb_dropout)

        if model == 3:
            self.transformer = FSATransformerEncoder(dim, depth, heads, dim_head, mlp_dim,
                                                     self.nt, self.nh, self.nw, dropout)
        elif model == 4:
            assert heads % 2 == 0, &quot;Number of heads should be even&quot;
            self.transformer = FDATransformerEncoder(dim, depth, heads, dim_head, mlp_dim,
                                                     self.nt, self.nh, self.nw, dropout)

        self.to_latent = nn.Identity()

        self.mlp_head = nn.Sequential(
            nn.LayerNorm(dim),
            nn.Linear(dim, num_classes)
        )

    def forward(self, x):
        &quot;&quot;&quot; x is a video: (b, C, T, H, W) &quot;&quot;&quot;


        tokens = self.to_tubelet_embedding(x)

        tokens += self.pos_embedding   #The error is because of this line
        tokens = self.dropout(tokens)

        x = self.transformer(tokens)
        return x

This is the error:

I create the ViViT according to the following method inside my model class:
self.vivit_FSA_F_8 = ViViTBackbone(t=8, h=16, w=24,   patch_t=1,   patch_h=16,   patch_w=24,  num_classes=10,  dim=128,
                            depth=6,  heads=10,  mlp_dim=8,   model=3)


How can I fix that?

There are multiple ways:
Instead of creating parameters like:
self.T = t

do:
self.T = nn.Parameter(t)

then model.to(device) will push all the parameters to the correct device too.
An alternative is to use the device parameter whenever you create a tensor
some_tensor = torch.tensor(1.0,device=self.device)

or
some_tensor = torch.ones([3,4],device=self.device)

