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21_Sigmoidoptimized_sigmoid_limited_sync_base

Level 1 • Task 21
import torch
import torch.nn as nn
import torch.nn.functional as F


def module_fn(x: torch.Tensor) -> torch.Tensor:
    """
    Applies Sigmoid activation to the input tensor.

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

    Returns:
        torch.Tensor: Output tensor with Sigmoid applied, same shape as input.
    """
    return torch.sigmoid(x)


class Model(nn.Module):
    """
    Simple model that performs a Sigmoid activation.
    """

    def __init__(self):
        super(Model, self).__init__()

    def forward(self, x: torch.Tensor, fn=module_fn) -> torch.Tensor:
        return fn(x)


batch_size = 16
dim = 16384


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


def get_init_inputs():
    return []  # No special initialization inputs needed
import torch
import torch.nn as nn

class Model(nn.Module):
    """
    Simple model that performs a Sigmoid activation.
    """
    def __init__(self):
        super(Model, self).__init__()
    
    def forward(self, x: torch.Tensor) -> torch.Tensor:
        """
        Applies Sigmoid activation to the input tensor.

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

        Returns:
            torch.Tensor: Output tensor with Sigmoid applied, same shape as input.
        """
        return torch.sigmoid(x)

batch_size = 16
dim = 16384

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

def get_init_inputs():
    return []  # No special initialization inputs needed

Kernel Information

Related Kernels (Level 1, Task 21 • 21_Sigmoid)

Rank Kernel Name Runtime (ms) Speedup Native Speedup Compile
🥇 sigmoid_shared_mem_optimized_base 0.01 1.11 4.82
🥇 21_sigmoid_modular_device_base 0.01 1.11 4.82
🥇 sigmoid_unroll_optimized_base_base 0.01 1.11 4.82
🥇 sigmoid_min_sync_base_base 0.01 1.11 4.82
🥇 optimized_sigmoid_cuda_base 0.01 1.11 4.82
🥇 optimized_sigmoid_limited_sync_base 0.01 1.11 4.82
🥇 sigmoid_ldg_vectorized_base 0.01 1.11 4.82
🥇 optimized_sigmoid_cuda_base 0.01 1.11 4.82
🥇 optimized_sigmoid_vectorized_combined_edit_1 0.01 1.11 4.82
🥇 21_Sigmoid_optimized_memory_base 0.01 1.11 4.82
🥇 sigmoid_minimal_sync_base_base 0.01 1.11 4.82
🥇 vectorized_ldg_aligned_edit_1 0.01 1.11 4.82
🥇 nondivergent_vectorized_sigmoid_base 0.01 1.11 4.82
🥇 vectorized_no_sync_base 0.01 1.11 4.82
🥇 vectorized_sigmoid_base 0.01 1.11 4.82
🥇 syncthreads_minimal_sigmoid_base 0.01 1.11 4.82
🥇 vectorized_ldg_aligned_base 0.01 1.11 4.82
🥇 optimized_sigmoid_vectorized_combined_base 0.01 1.11 4.82
🥇 optimized_sigmoid_blocksize_tuning_edit_1 0.01 1.11 4.82
🥇 optimized_sigmoid_blocksize_tuning_base 0.01 1.11 4.82
#include <torch/extension.h>
#include <cuda.h>
#include <cuda_runtime.h>

const int THREADS = 256;
const int ELEMENTS_PER_THREAD = 4;
const int SHARED_MEM_SIZE = THREADS * ELEMENTS_PER_THREAD;

// Kernel optimized by minimizing unnecessary __syncthreads() usage

template <typename scalar_t>
__global__ void sigmoid_kernel(const scalar_t* __restrict__ input,
                             scalar_t* __restrict__ output,
                             const int64_t size) {
    __shared__ float shared_data[SHARED_MEM_SIZE];
    
    const int tid = threadIdx.x;
    const int block_offset = blockIdx.x * SHARED_MEM_SIZE;
    
    using Vec4T = float4;
    const Vec4T* input_vec = reinterpret_cast<const Vec4T*>(input + block_offset);
    Vec4T* output_vec = reinterpret_cast<Vec4T*>(output + block_offset);
    
    if (block_offset + tid * 4 + 3 < size) {
        Vec4T in_vec = input_vec[tid];
        shared_data[tid * 4 + 0] = in_vec.x;
        shared_data[tid * 4 + 1] = in_vec.y;
        shared_data[tid * 4 + 2] = in_vec.z;
        shared_data[tid * 4 + 3] = in_vec.w;
    } else {
        #pragma unroll
        for (int i = 0; i < 4; i++) {
            int idx = block_offset + tid * 4 + i;
            if (idx < size) {
                shared_data[tid * 4 + i] = static_cast<float>(input[idx]);
            }
        }
    }
    __syncthreads();
    
    #pragma unroll
    for (int i = 0; i < 4; i++) {
        const int idx = block_offset + tid * 4 + i;
        if (idx < size) {
            float val = -shared_data[tid * 4 + i];
            float exp_val = __expf(val);
            float r = __fdividef(1.0f, (1.0f + exp_val));
            shared_data[tid * 4 + i] = r;
        }
    }
    
    if (block_offset + tid * 4 + 3 < size) {
        Vec4T out_vec;
        out_vec.x = shared_data[tid * 4 + 0];
        out_vec.y = shared_data[tid * 4 + 1];
        out_vec.z = shared_data[tid * 4 + 2];
        out_vec.w = shared_data[tid * 4 + 3];
        output_vec[tid] = out_vec;
    } else {
        #pragma unroll
        for (int i = 0; i < 4; i++) {
            int idx = block_offset + tid * 4 + i;
            if (idx < size) {
                output[idx] = static_cast<scalar_t>(shared_data[tid * 4 + i]);
            }
        }
    }
}

torch::Tensor forward(torch::Tensor input) {
    auto output = torch::empty_like(input);
    const int64_t size = input.numel();
    
    const int blocks = (size + SHARED_MEM_SIZE - 1) / SHARED_MEM_SIZE;
    
    AT_DISPATCH_FLOATING_TYPES(input.scalar_type(), "sigmoid_kernel", [&] {
        const auto* input_data = input.data_ptr<scalar_t>();
        auto* output_data = output.data_ptr<scalar_t>();
        
        sigmoid_kernel<scalar_t><<<blocks, THREADS>>>(input_data, output_data, size);
    });
    
    return output;
}

PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def("forward", &forward, "Optimized Sigmoid forward (CUDA)");
}
Performance Metrics
Metric Value Unit Variance Samples
Executed Ipc Active 0.470 inst/cycle 0.001 5
Executed Ipc Elapsed 0.194 inst/cycle 0.000 5
Issue Slots Busy 12.408 % 0.398 5
Issued Ipc Active 0.498 inst/cycle 0.001 5
SM Busy 12.408 % 0.398 5
Memory Throughput 275131175063.508 byte/second 22144518040700616704.000 5
Mem Busy 13.062 % 0.063 5
Max Bandwidth 12.046 % 0.056 5
L1/TEX Hit Rate 0.000 % 0.000 5
L2 Hit Rate 67.252 % 0.032 5
Mem Pipes Busy 4.092 % 0.005 5
Warp Cycles Per Issued Instruction 29.272 cycle 0.804 5
Warp Cycles Per Executed Instruction 30.836 cycle 0.886 5
Avg. Active Threads Per Warp 32.000 0.000 5
Avg. Not Predicated Off Threads Per Warp 32.000 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 20.000 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 22.942 % 0.008 5
Achieved Active Warps Per SM 14.684 warp 0.003 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 (22.9%) 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 470833.33 μs
Device Time 39.90 μs
Self CPU Time 36.90 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 470796.43 μs
Device Time 39.90 μs
Self CPU Time 79.33 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 490207.62 μs
Device Time 0.00 μs
Self CPU Time 19823.43 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 466278.42 μs
Device Time 0.00 μs
Self CPU Time 466278.42 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 504310.15 μs
Device Time 22649.36 μs
Self CPU Time 504310.15 μs
Self Device Time 22649.36 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
void sigmoid_kernel<float>(float const*, float*, long)
CPU Time 0.00 μs
Device Time 31793.16 μs
Self CPU Time 0.00 μs
Self Device Time 31793.16 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 20027.04 μs
Device Time 43648.30 μs
Self CPU Time 20027.04 μs
Self Device Time 43648.30 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 64259.55 μs
Device Time 646213.72 μs
Self CPU Time 13402.30 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 50858.38 μs
Device Time 646213.72 μs
Self CPU Time 16440.52 μs
Self Device Time 646213.72 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 646213.72 μs
Self CPU Time 0.00 μs
Self Device Time 646213.72 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
45280 warnings generated when compiling for host.
Suppressed 45321 warnings (45274 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_21/b7_s1_optimized_sigmoid_limited_sync/base/base.cu:17:21 bugprone-narrowing-conversions
17 | const int tid = threadIdx.x;
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_21/b7_s1_optimized_sigmoid_limited_sync/base/base.cu:18:30: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
18 | const int block_offset = blockIdx.x * SHARED_MEM_SIZE;
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_21/b7_s1_optimized_sigmoid_limited_sync/base/base.cu:74:24: warning: narrowing conversion from 'int64_t' (aka 'long') to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
74 | const int blocks = (size + SHARED_MEM_SIZE - 1) / SHARED_MEM_SIZE;
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_21/b7_s1_optimized_sigmoid_limited_sync/base/base.cu:76:5: warning: inside a lambda, '__func__' expands to the name of the function call operator; consider capturing the name of the enclosing function explicitly [bugprone-lambda-function-name]
76 | AT_DISPATCH_FLOATING_TYPES(input.scalar_type(), "sigmoid_kernel", [&] {
| ^
/home/robert_sakana_ai/miniconda3/envs/llm2cuda/lib/python3.11/site-packages/torch/include/ATen/Dispatch.h:237:34: note: expanded from macro 'AT_DISPATCH_FLOATING_TYPES'
237 | AT_DISPATCH_SWITCH(TYPE, NAME, AT_DISPATCH_CASE_FLOATING_TYPES(__VA_ARGS__))
| ^
/home/robert_sakana_ai/miniconda3/envs/llm2cuda/lib/python3.11/site-packages/torch/include/ATen/Dispatch.h:233:3: note: expanded from macro 'AT_DISPATCH_CASE_FLOATING_TYPES'
233 | AT_DISPATCH_CASE(at::ScalarType::Double, __VA_ARGS__) \
| ^
/home/robert_sakana_ai/miniconda3/envs/llm2cuda/lib/python3.11/site-packages/torch/include/ATen/Dispatch.h:74:3: note: expanded from macro 'AT_DISPATCH_CASE'
74 | AT_PRIVATE_CASE_TYPE_USING_HINT(enum_type, scalar_t, __VA_ARGS__)
| ^
note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/home/robert_sakana_ai/miniconda3/envs/llm2cuda/lib/python3.11/site-packages/torch/include/ATen/Dispatch.h:58:7: note: expanded from macro 'AT_PRIVATE_CHECK_SELECTIVE_BUILD'
58 | AT_ERROR( \
| ^
/home/robert_sakana_ai/miniconda3/envs/llm2cuda/lib/python3.11/site-packages/torch/include/c10/util/Exception.h:711:32: note: expanded from macro 'AT_ERROR'
711 | C10_EXPAND_MSVC_WORKAROUND(TORCH_CHECK(false, ::c10::str(__VA_ARGS__))); \
| ^
/home/robert_sakana_ai/miniconda3/envs/llm2cuda/lib/python3.11/site-packages/torch/include/c10/util/Exception.h:536:9: note: expanded from macro 'TORCH_CHECK'
536 | __func__, \
| ^