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31_ELU31_elu_shared_base

Level 1 • Task 31
import torch
import torch.nn as nn
import torch.nn.functional as F


def module_fn(x: torch.Tensor, alpha: float) -> torch.Tensor:
    """
    Applies ELU activation to the input tensor.

    Args:
        x (torch.Tensor): Input tensor of any shape.
        alpha (float): The alpha parameter for the ELU function.

    Returns:
        torch.Tensor: Output tensor with ELU applied, same shape as input.
    """
    return F.elu(x, alpha=alpha)


class Model(nn.Module):
    """
    Simple model that performs an ELU activation.
    """

    def __init__(self, alpha):
        """
        Initializes the ELU model.

        Args:
            alpha (float): The alpha parameter for the ELU function.
        """
        super(Model, self).__init__()
        self.alpha = alpha

    def forward(self, x: torch.Tensor, fn=module_fn) -> torch.Tensor:
        """
        Applies ELU activation to the input tensor.

        Args:
            x (torch.Tensor): Input tensor of any shape.

        Returns:
            torch.Tensor: Output tensor with ELU applied, same shape as input.
        """
        return fn(x, self.alpha)


batch_size = 16
dim = 16384
alpha = 1.0


def get_inputs():
    x = torch.randn(batch_size, dim)
    return [x]


def get_init_inputs():
    return [alpha]
import torch
import torch.nn as nn
import torch.nn.functional as F

class Model(nn.Module):
    """
    Simple model that performs an ELU activation.
    """
    def __init__(self, alpha: float = 1.0):
        """
        Initializes the ELU model.

        Args:
            alpha (float, optional): The alpha parameter for the ELU function. Defaults to 1.0.
        """
        super(Model, self).__init__()
        self.alpha = alpha
    
    def forward(self, x: torch.Tensor) -> torch.Tensor:
        """
        Applies ELU activation to the input tensor.

        Args:
            x (torch.Tensor): Input tensor of any shape.

        Returns:
            torch.Tensor: Output tensor with ELU applied, same shape as input.
        """
        return F.elu(x, alpha=self.alpha)

batch_size = 16
dim = 16384

def get_inputs():
    x = torch.randn(batch_size, dim)
    return [x]

def get_init_inputs():
    return [1.0]  # Provide alpha value for initialization

Kernel Information

Related Kernels (Level 1, Task 31 • 31_ELU)

Rank Kernel Name Runtime (ms) Speedup Native Speedup Compile
🥇 31_elu_shared_base 0.01 1.14 4.80
🥇 hybrid_elu_optimized_base 0.01 1.14 4.80
🥇 31_elu_vectorized_base 0.01 1.14 4.80
🥇 vec_shared_elu_base 0.01 1.14 4.80
🥇 31_elu_grid_stride_base_base 0.01 1.14 4.80
🥇 31_elu_vectorized_edit_1 0.01 1.14 4.80
🥇 elu_unroll_kernel_base 0.01 1.14 4.80
🥇 ldg_elu_128_base 0.01 1.14 4.80
9 31_ELU 0.01 0.97 4.12
9 31_elu_aligned_coalesced_base 0.01 0.97 4.12
9 hybrid_elu_base 0.01 0.97 4.12
9 31_elu_optimized_indexing_base 0.01 0.97 4.12
9 31_elu_reduced_divergence_base 0.01 0.97 4.12
9 elu_hybrid_base 0.01 0.97 4.12
9 31_elu_coalesced_base 0.01 0.97 4.12
9 31_elu_shared_mem_base 0.01 0.97 4.12
9 modular_elu_base 0.01 0.97 4.12
9 elu_vec4_shared_base 0.01 0.97 4.12
9 elu_tuned_blocksize_base 0.01 0.97 4.12
9 branchless_elu_vectorized_base 0.01 0.97 4.12
#include <torch/extension.h>
#include <cuda.h>
#include <cuda_runtime.h>
#include <math.h>

#define CHECK_CUDA(x) TORCH_CHECK(x.is_cuda(), #x " must be a CUDA tensor")
#define CHECK_CONTIGUOUS(x) TORCH_CHECK(x.is_contiguous(), #x " must be contiguous")
#define CHECK_INPUT(x) CHECK_CUDA(x); CHECK_CONTIGUOUS(x)

// CUDA kernel leveraging shared memory to preload a tile of input data
__global__ void elu_kernel_shared(const float* x, float* out, float alpha, int n) {
    extern __shared__ float tile[]; // dynamically allocated shared memory
    int tid = threadIdx.x;
    int globalIdx = blockIdx.x * blockDim.x + tid;

    // Load input data from global memory to shared memory if within bounds
    if (globalIdx < n) {
        tile[tid] = x[globalIdx];
    }
    __syncthreads(); // Ensure all threads have loaded data to shared memory before processing

    // Compute the ELU activation using data from shared memory
    if (globalIdx < n) {
        float val = tile[tid];
        out[globalIdx] = (val > 0.0f) ? val : alpha * (expf(val) - 1.0f);
    }
}

// Interface function called from Python
torch::Tensor elu_cuda_shared(torch::Tensor x, float alpha) {
    CHECK_INPUT(x);

    auto out = torch::empty_like(x);
    int n = x.numel();
    
    // Use block size of 256 threads
    const int threads = 256;
    const int blocks = (n + threads - 1) / threads;
    
    // Allocate shared memory per block
    size_t sharedMemSize = threads * sizeof(float);
    
    elu_kernel_shared<<<blocks, threads, sharedMemSize>>>(x.data_ptr<float>(), out.data_ptr<float>(), alpha, n);
    
    return out;
}

PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def("forward", &elu_cuda_shared, "ELU activation with shared memory (CUDA)");
}
Performance Metrics
Metric Value Unit Variance Samples
Executed Ipc Active 0.742 inst/cycle 0.001 5
Executed Ipc Elapsed 0.296 inst/cycle 0.000 5
Issue Slots Busy 20.962 % 0.937 5
Issued Ipc Active 0.838 inst/cycle 0.002 5
SM Busy 20.962 % 0.937 5
Memory Throughput 272954988986.316 byte/second 17600545736449437696.000 5
Mem Busy 13.008 % 0.033 5
Max Bandwidth 12.060 % 0.034 5
L1/TEX Hit Rate 0.000 % 0.000 5
L2 Hit Rate 66.082 % 0.219 5
Mem Pipes Busy 16.202 % 0.062 5
Warp Cycles Per Issued Instruction 60.728 cycle 0.023 5
Warp Cycles Per Executed Instruction 68.514 cycle 0.029 5
Avg. Active Threads Per Warp 32.000 0.000 5
Avg. Not Predicated Off Threads Per Warp 28.140 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 16.000 block 0.000 5
Block Limit Shared Mem 16.000 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 82.532 % 0.686 5
Achieved Active Warps Per SM 52.820 warp 0.280 5
Analysis Rules
Rule Description
WRN HighPipeUtilization All compute pipelines are under-utilized. Either this kernel is very small or it doesn't issue enough warps per scheduler. Check the Launch Statistics and Scheduler Statistics sections for further details.
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 (84.2%) 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::to
CPU Time 642168.55 μs
Device Time 40.16 μs
Self CPU Time 31.07 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::_to_copy
CPU Time 642137.48 μs
Device Time 40.16 μs
Self CPU Time 81.48 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::empty_strided
CPU Time 658447.52 μs
Device Time 0.00 μs
Self CPU Time 16744.01 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
cudaDeviceGetStreamPriorityRange
CPU Time 641464.79 μs
Device Time 0.00 μs
Self CPU Time 641464.79 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 406572.36 μs
Device Time 18483.25 μs
Self CPU Time 406572.36 μs
Self Device Time 18483.25 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
elu_kernel_shared(float const*, float*, float, int)
CPU Time 0.00 μs
Device Time 26032.53 μs
Self CPU Time 0.00 μs
Self Device Time 26032.53 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
cudaEventRecord
CPU Time 19293.87 μs
Device Time 35635.29 μs
Self CPU Time 19293.87 μs
Self Device Time 35635.29 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
aten::zero_
CPU Time 57360.72 μs
Device Time 529649.91 μs
Self CPU Time 10151.61 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::fill_
CPU Time 47211.03 μs
Device Time 529649.91 μs
Self CPU Time 12744.75 μs
Self Device Time 529649.91 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
void at::native::vectorized_elementwise_kernel<4, at::native::FillFunctor<int>, at::detail::Array<char*, 1> >(int, at::native::FillFunctor<int>, at::detail::Array<char*, 1>)
CPU Time 0.00 μs
Device Time 529728.66 μs
Self CPU Time 0.00 μs
Self Device Time 529728.66 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
45282 warnings generated when compiling for host.
Suppressed 45322 warnings (45275 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/20250202_optimize_b10_s4_e0_sweep/level_1/task_31/b2_s2_31_elu_shared/base/base.cu:6:35 bugprone-macro-parentheses
6 | #define CHECK_CUDA(x) TORCH_CHECK(x.is_cuda(), #x " must be a CUDA tensor")
| ^
| ()
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_31/b2_s2_31_elu_shared/base/base.cu:7:41: warning: macro argument should be enclosed in parentheses [bugprone-macro-parentheses]
7 | #define CHECK_CONTIGUOUS(x) TORCH_CHECK(x.is_contiguous(), #x " must be contiguous")
| ^
| ()
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_31/b2_s2_31_elu_shared/base/base.cu:11:63: warning: 2 adjacent parameters of 'elu_kernel_shared' of convertible types are easily swapped by mistake [bugprone-easily-swappable-parameters]
11 | __global__ void elu_kernel_shared(const float* x, float* out, float alpha, int n) {
| ^~~~~~~~~~~~~~~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_31/b2_s2_31_elu_shared/base/base.cu:11:69: note: the first parameter in the range is 'alpha'
11 | __global__ void elu_kernel_shared(const float* x, float* out, float alpha, int n) {
| ^~~~~
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_31/b2_s2_31_elu_shared/base/base.cu:11:80: note: the last parameter in the range is 'n'
11 | __global__ void elu_kernel_shared(const float* x, float* out, float alpha, int n) {
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_31/b2_s2_31_elu_shared/base/base.cu:11:76: note: 'float' and 'int' may be implicitly converted
11 | __global__ void elu_kernel_shared(const float* x, float* out, float alpha, int n) {
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_31/b2_s2_31_elu_shared/base/base.cu:13:15: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
13 | int tid = threadIdx.x;
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_31/b2_s2_31_elu_shared/base/base.cu:14:21: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
14 | int globalIdx = blockIdx.x * blockDim.x + tid;
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_31/b2_s2_31_elu_shared/base/base.cu:30:45: warning: the parameter 'x' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param]
30 | torch::Tensor elu_cuda_shared(torch::Tensor x, float alpha) {
| ^
| const &
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_31/b2_s2_31_elu_shared/base/base.cu:34:13: warning: narrowing conversion from 'int64_t' (aka 'long') to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
34 | int n = x.numel();
| ^