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3_ConvTranspose3d_Sum_LayerNorm_AvgPool_GELUwarp_optimized_layernorm_base_base

Level 2 • Task 3
import torch
import torch.nn as nn
import torch.nn.functional as F


def module_fn(
    x: torch.Tensor,
    conv_transpose_weight: torch.Tensor,
    conv_transpose_bias: torch.Tensor,
    sum_weight: torch.Tensor,
    norm_weight: torch.Tensor,
    norm_bias: torch.Tensor,
    stride: tuple,
    padding: tuple,
    output_padding: tuple,
    pool_kernel_size: tuple,
    norm_shape: tuple,
) -> torch.Tensor:
    """
    Functional implementation of a sequence of operations:
    1. 3D transposed convolution
    2. Addition with a learnable weight
    3. Layer normalization
    4. 3D average pooling
    5. GELU activation

    Args:
        x (torch.Tensor): Input tensor of shape (batch_size, in_channels, depth, height, width)
        conv_transpose_weight (torch.Tensor): Weight tensor for transposed convolution
        conv_transpose_bias (torch.Tensor): Bias tensor for transposed convolution
        sum_weight (torch.Tensor): Learnable weight for addition
        norm_weight (torch.Tensor): Weight tensor for layer normalization
        norm_bias (torch.Tensor): Bias tensor for layer normalization
        stride (tuple): Stride for transposed convolution, as (depth_stride, height_stride, width_stride)
        padding (tuple): Padding for transposed convolution, as (depth_pad, height_pad, width_pad)
        output_padding (tuple): Output padding for transposed convolution, as (depth_pad, height_pad, width_pad)
        pool_kernel_size (tuple): Kernel size for average pooling, as (depth_kernel, height_kernel, width_kernel)
        norm_shape (tuple): Shape for layer normalization

    Returns:
        torch.Tensor: Output tensor after applying all operations
    """
    x = F.conv_transpose3d(
        x,
        conv_transpose_weight,
        bias=conv_transpose_bias,
        stride=stride,
        padding=padding,
        output_padding=output_padding,
    )
    x = x + sum_weight
    x = F.layer_norm(x, norm_shape, norm_weight, norm_bias)
    x = F.avg_pool3d(x, kernel_size=pool_kernel_size)
    x = F.gelu(x)
    return x


class Model(nn.Module):
    """
    Model that performs a 3D transposed convolution, followed by a sum, layer normalization, average pooling, and GELU activation.
    """

    def __init__(
        self,
        in_channels,
        out_channels,
        kernel_size,
        stride,
        padding,
        output_padding,
        sum_weight,
        norm_shape,
        pool_kernel_size,
    ):
        super(Model, self).__init__()
        conv = nn.ConvTranspose3d(
            in_channels,
            out_channels,
            kernel_size,
            stride=stride,
            padding=padding,
            output_padding=output_padding,
        )
        self.conv_transpose_weight = nn.Parameter(conv.weight)
        self.conv_transpose_bias = nn.Parameter(conv.bias)
        self.sum_weight = nn.Parameter(torch.tensor(sum_weight))
        norm = nn.LayerNorm(norm_shape)
        self.norm_weight = nn.Parameter(norm.weight + torch.randn(norm_shape) * 0.02)
        self.norm_bias = nn.Parameter(norm.bias + torch.randn(norm_shape) * 0.02)

    def forward(
        self,
        x,
        stride,
        padding,
        output_padding,
        pool_kernel_size,
        norm_shape,
        fn=module_fn,
    ):
        return fn(
            x,
            self.conv_transpose_weight,
            self.conv_transpose_bias,
            self.sum_weight,
            self.norm_weight,
            self.norm_bias,
            stride,
            padding,
            output_padding,
            pool_kernel_size,
            norm_shape,
        )


batch_size = 128
in_channels = 32
out_channels = 64
depth, height, width = 16, 32, 32
kernel_size = (3, 3, 3)
stride = (2, 2, 2)
padding = (1, 1, 1)
output_padding = (1, 1, 1)
sum_weight = 1.0
norm_shape = (out_channels,)
pool_kernel_size = (2, 2, 2)


def get_inputs():
    return [
        torch.randn(batch_size, in_channels, depth, height, width),
        stride,
        padding,
        output_padding,
        pool_kernel_size,
        norm_shape,
    ]


def get_init_inputs():
    return [
        in_channels,
        out_channels,
        kernel_size,
        stride,
        padding,
        output_padding,
        sum_weight,
        norm_shape,
        pool_kernel_size,
    ]
import torch
import torch.nn as nn

class Model(nn.Module):
    """
    Model that performs a 3D transposed convolution, followed by a sum, layer normalization, average pooling, and GELU activation.
    """
    def __init__(self, in_channels, out_channels, kernel_size, stride, padding, output_padding, sum_weight, norm_shape, pool_kernel_size):
        super(Model, self).__init__()
        self.conv_transpose = nn.ConvTranspose3d(in_channels, out_channels, kernel_size, stride=stride, padding=padding, output_padding=output_padding)
        self.sum_weight = nn.Parameter(torch.tensor(sum_weight))
        self.norm = nn.LayerNorm(norm_shape)
        self.norm.weight = nn.Parameter(self.norm.weight + torch.randn(norm_shape)*0.02)
        self.norm.bias = nn.Parameter(self.norm.bias + torch.randn(norm_shape)*0.02)
        self.avg_pool = nn.AvgPool3d(kernel_size=pool_kernel_size)
        self.gelu = nn.GELU()

    def forward(self, x):
        x = self.conv_transpose(x)
        x = x + self.sum_weight
        x = self.norm(x)
        x = self.avg_pool(x)
        x = self.gelu(x)
        return x

batch_size = 128
in_channels = 32
out_channels = 64
depth, height, width = 16, 32, 32
kernel_size = (3, 3, 3)
stride = (2, 2, 2)
padding = (1, 1, 1)
output_padding = (1, 1, 1)
sum_weight = 1.0
norm_shape = (out_channels,)
pool_kernel_size = (2, 2, 2)

def get_inputs():
    return [torch.randn(batch_size, in_channels, depth, height, width)]

def get_init_inputs():
    return [in_channels, out_channels, kernel_size, stride, padding, output_padding, sum_weight, norm_shape, pool_kernel_size]

Kernel Information

Related Kernels (Level 2, Task 3 • 3_ConvTranspose3d_Sum_LayerNorm_AvgPool_GELU)

#include <torch/extension.h>
#include <ATen/ATen.h>
#include <cuda_runtime.h>
#include <vector>

#define BLOCK_SIZE 256
#define WARP_SIZE 32
#define WARPS_PER_BLOCK (BLOCK_SIZE/WARP_SIZE)

template <typename T>
__global__ void warp_optimized_layernorm_kernel(
    const T* __restrict__ input,
    const T* __restrict__ gamma,
    const T* __restrict__ beta,
    T* __restrict__ output,
    const int n1,
    const int n2
) {
    __shared__ float s_mean[WARPS_PER_BLOCK];
    __shared__ float s_var[WARPS_PER_BLOCK];
    
    const unsigned int tid = threadIdx.x;
    const unsigned int lane_id = tid % WARP_SIZE;
    const unsigned int warp_id = tid / WARP_SIZE;
    const unsigned int bid = blockIdx.x;
    
    float local_sum = 0.0f;
    float local_sq_sum = 0.0f;
    
    const int offset = bid * n2;
    
    #pragma unroll 4
    for (int i = tid; i < n2; i += BLOCK_SIZE) {
        float val = __ldg(&input[offset + i]);
        local_sum += val;
        local_sq_sum += val * val;
    }
    
    #pragma unroll
    for (int delta = WARP_SIZE/2; delta > 0; delta >>= 1) {
        local_sum += __shfl_xor_sync(0xffffffff, local_sum, delta);
        local_sq_sum += __shfl_xor_sync(0xffffffff, local_sq_sum, delta);
    }
    
    if (lane_id == 0) {
        s_mean[warp_id] = local_sum;
        s_var[warp_id] = local_sq_sum;
    }
    __syncthreads();
    
    if (warp_id == 0) {
        local_sum = (lane_id < WARPS_PER_BLOCK) ? s_mean[lane_id] : 0.0f;
        local_sq_sum = (lane_id < WARPS_PER_BLOCK) ? s_var[lane_id] : 0.0f;
        
        #pragma unroll
        for (int delta = WARP_SIZE/2; delta > 0; delta >>= 1) {
            local_sum += __shfl_xor_sync(0xffffffff, local_sum, delta);
            local_sq_sum += __shfl_xor_sync(0xffffffff, local_sq_sum, delta);
        }
        
        if (lane_id == 0) {
            s_mean[0] = local_sum / n2;
            s_var[0] = (local_sq_sum / n2) - (s_mean[0] * s_mean[0]);
        }
    }
    __syncthreads();
    
    const float mean = s_mean[0];
    const float inv_std = rsqrtf(s_var[0] + 1e-5f);
    
    #pragma unroll 4
    for (int i = tid; i < n2; i += BLOCK_SIZE) {
        const int idx = offset + i;
        const float normalized = (input[idx] - mean) * inv_std;
        output[idx] = gamma[i] * normalized + beta[i];
    }
}

torch::Tensor forward(
    torch::Tensor x,
    torch::Tensor conv_transpose_weight,
    torch::Tensor conv_transpose_bias,
    torch::Tensor sum_weight,
    torch::Tensor norm_weight,
    torch::Tensor norm_bias,
    std::vector<int64_t> stride,
    std::vector<int64_t> padding,
    std::vector<int64_t> output_padding,
    std::vector<int64_t> pool_kernel_size,
    std::vector<int64_t> norm_shape
) {
    x = x.contiguous();
    conv_transpose_weight = conv_transpose_weight.contiguous();
    sum_weight = sum_weight.contiguous();
    norm_weight = norm_weight.contiguous();
    norm_bias = norm_bias.contiguous();
    
    at::IntArrayRef strideRef(stride);
    at::IntArrayRef paddingRef(padding);
    at::IntArrayRef outputPaddingRef(output_padding);
    at::IntArrayRef poolKernelRef(pool_kernel_size);
    
    auto out = at::conv_transpose3d(
        x,
        conv_transpose_weight,
        conv_transpose_bias,
        strideRef,
        paddingRef,
        outputPaddingRef,
        1,
        1
    );
    
    out.add_(sum_weight);
    
    auto out_size = out.sizes();
    int64_t n1 = 1;
    for (int i = 0; i < out.dim() - norm_shape.size(); ++i) {
        n1 *= out_size[i];
    }
    int64_t n2 = 1;
    for (size_t i = 0; i < norm_shape.size(); ++i) {
        n2 *= norm_shape[i];
    }
    
    auto output = torch::empty_like(out);
    dim3 grid(n1);
    dim3 block(BLOCK_SIZE);
    
    warp_optimized_layernorm_kernel<<<grid, block>>>(
        out.data_ptr<float>(),
        norm_weight.data_ptr<float>(),
        norm_bias.data_ptr<float>(),
        output.data_ptr<float>(),
        n1,
        n2
    );
    
    output = at::gelu(at::avg_pool3d(
        output,
        poolKernelRef,
        poolKernelRef,
        {0,0,0},
        false,
        true
    ));
    
    return output;
}

PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def("forward", &forward, "Warp optimized module_fn forward (CUDA)");
}
Performance Metrics
Metric Value Unit Variance Samples
Executed Ipc Active 2.290 inst/cycle 0.000 5
Executed Ipc Elapsed 2.290 inst/cycle 0.000 5
Issue Slots Busy 58.154 % 0.000 5
Issued Ipc Active 2.330 inst/cycle 0.000 5
SM Busy 58.154 % 0.000 5
Memory Throughput 382499820595.464 byte/second 925873378621357.000 5
Mem Busy 52.562 % 0.000 5
Max Bandwidth 47.062 % 0.000 5
L1/TEX Hit Rate 59.950 % 0.000 5
L2 Hit Rate 50.044 % 0.000 5
Mem Pipes Busy 49.918 % 0.000 5
Warp Cycles Per Issued Instruction 22.640 cycle 0.000 5
Warp Cycles Per Executed Instruction 22.960 cycle 0.000 5
Avg. Active Threads Per Warp 27.400 0.000 5
Avg. Not Predicated Off Threads Per Warp 26.330 0.000 5
Max Active Clusters 0.000 cluster 0.000 5
Max Cluster Size 8.000 block 0.000 5
Overall GPU Occupancy 0.000 % 0.000 5
Cluster Occupancy 0.000 % 0.000 5
Block Limit SM 32.000 block 0.000 5
Block Limit Registers 10.000 block 0.000 5
Block Limit Shared Mem 28.000 block 0.000 5
Block Limit Warps 8.000 block 0.000 5
Theoretical Active Warps per SM 64.000 warp 0.000 5
Theoretical Occupancy 100.000 % 0.000 5
Achieved Occupancy 83.140 % 0.000 5
Achieved Active Warps Per SM 53.210 warp 0.000 5
Analysis Rules
Rule Description
INF HighPipeUtilization ALU is the highest-utilized pipeline (28.7%) based on active cycles, taking into account the rates of its different instructions. It executes integer and logic operations. It is well-utilized, but should not be a bottleneck.
INF CPIStall Check the Warp Stall Sampling (All Cycles) table for the top stall locations in your source based on sampling data. The Kernel Profiling Guide (https://docs.nvidia.com/nsight-compute/ProfilingGuide/index.html#metrics-reference) provides more details on each stall reason.
WRN Occupancy This kernel's theoretical occupancy is not impacted by any block limit. The difference between calculated theoretical (100.0%) and measured achieved occupancy (83.1%) can be the result of warp scheduling overheads or workload imbalances during the kernel execution. Load imbalances can occur between warps within a block as well as across blocks of the same kernel. See the CUDA Best Practices Guide (https://docs.nvidia.com/cuda/cuda-c-best-practices-guide/index.html#occupancy) for more details on optimizing occupancy.
Operation / Metric Value Unit
aten::conv_transpose3d
CPU Time 1364391.02 μs
Device Time 2588067.38 μs
Self CPU Time 667.01 μs
Self Device Time 0.00 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
aten::convolution
CPU Time 1363724.01 μs
Device Time 2588067.38 μs
Self CPU Time 894.85 μs
Self Device Time 0.00 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
aten::_convolution
CPU Time 1362829.16 μs
Device Time 2588067.38 μs
Self CPU Time 1852.74 μs
Self Device Time 0.00 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
cudaLaunchKernel
CPU Time 7603619.02 μs
Device Time 6466.66 μs
Self CPU Time 7603619.02 μs
Self Device Time 6466.66 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
aten::add_
CPU Time 1924685.43 μs
Device Time 1951129.88 μs
Self CPU Time 4611.63 μs
Self Device Time 1951129.88 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
void warp_optimized_layernorm_kernel<float>(float const*, float const*, float const*, float*, int, int)
CPU Time 0.00 μs
Device Time 5597026.19 μs
Self CPU Time 0.00 μs
Self Device Time 5597026.19 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
aten::avg_pool3d
CPU Time 4922730.33 μs
Device Time 801301.25 μs
Self CPU Time 3534.69 μs
Self Device Time 801301.25 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
cudaDeviceSynchronize
CPU Time 2390095.57 μs
Device Time 3720.40 μs
Self CPU Time 2390095.57 μs
Self Device Time 3720.40 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
Status: Completed
45298 warnings generated when compiling for host.
Suppressed 45331 warnings (45284 in non-user code, 47 NOLINT).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:12:5 bugprone-easily-swappable-parameters
12 | const T* __restrict__ input,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
13 | const T* __restrict__ gamma,
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:12:27: note: the first parameter in the range is 'input'
12 | const T* __restrict__ input,
| ^~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:13:27: note: the last parameter in the range is 'gamma'
13 | const T* __restrict__ gamma,
| ^~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:30:24: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
30 | const int offset = bid * n2;
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:33:18: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
33 | for (int i = tid; i < n2; i += BLOCK_SIZE) {
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:62:37: warning: narrowing conversion from 'int' to 'float' [bugprone-narrowing-conversions]
62 | s_mean[0] = local_sum / n2;
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:63:40: warning: narrowing conversion from 'int' to 'float' [bugprone-narrowing-conversions]
63 | s_var[0] = (local_sq_sum / n2) - (s_mean[0] * s_mean[0]);
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:72:18: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
72 | for (int i = tid; i < n2; i += BLOCK_SIZE) {
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:82:5: warning: 2 adjacent parameters of 'forward' of similar type ('torch::Tensor') are easily swapped by mistake [bugprone-easily-swappable-parameters]
82 | torch::Tensor conv_transpose_bias,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
83 | torch::Tensor sum_weight,
| ~~~~~~~~~~~~~~~~~~~~~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:82:19: note: the first parameter in the range is 'conv_transpose_bias'
82 | torch::Tensor conv_transpose_bias,
| ^~~~~~~~~~~~~~~~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:83:19: note: the last parameter in the range is 'sum_weight'
83 | torch::Tensor sum_weight,
| ^~~~~~~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:86:5: warning: 5 adjacent parameters of 'forward' of similar type ('std::vector<int64_t>') are easily swapped by mistake [bugprone-easily-swappable-parameters]
86 | std::vector<int64_t> stride,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
87 | std::vector<int64_t> padding,
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
88 | std::vector<int64_t> output_padding,
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
89 | std::vector<int64_t> pool_kernel_size,
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
90 | std::vector<int64_t> norm_shape
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:86:26: note: the first parameter in the range is 'stride'
86 | std::vector<int64_t> stride,
| ^~~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:90:26: note: the last parameter in the range is 'norm_shape'
90 | std::vector<int64_t> norm_shape
| ^~~~~~~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:86:26: warning: the parameter 'stride' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param]
86 | std::vector<int64_t> stride,
| ^
| const &
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:87:26: warning: the parameter 'padding' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param]
87 | std::vector<int64_t> padding,
| ^
| const &
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:88:26: warning: the parameter 'output_padding' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param]
88 | std::vector<int64_t> output_padding,
| ^
| const &
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:89:26: warning: the parameter 'pool_kernel_size' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param]
89 | std::vector<int64_t> pool_kernel_size,
| ^
| const &
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:135:9: warning: narrowing conversion from 'int64_t' (aka 'long') to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
135 | n1,
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250203_optimize_b10_s4_e0_sweep/level_2/task_3/b5_s1_warp_optimized_layernorm_base/base/base.cu:136:9: warning: narrowing conversion from 'int64_t' (aka 'long') to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
136 | n2
| ^