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21_Sigmoidsigmoid_min_sync_base_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 __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] = 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]);
            }
        }
    }
    // Synchronize only after loading data into shared memory
    __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;
        }
    }
    // Synchronize only if data is needed by other threads
    __syncthreads();
    
    if (block_offset + tid * 4 + 3 < size) {
        Vec4T out_vec;
        out_vec.x = shared_data[tid * 4];
        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 0.482 inst/cycle 0.000 5
Executed Ipc Elapsed 0.200 inst/cycle 0.000 5
Issue Slots Busy 12.694 % 0.075 5
Issued Ipc Active 0.508 inst/cycle 0.000 5
SM Busy 12.694 % 0.075 5
Memory Throughput 281184284693.810 byte/second 2310912917160634880.000 5
Mem Busy 13.300 % 0.011 5
Max Bandwidth 12.294 % 0.003 5
L1/TEX Hit Rate 0.000 % 0.000 5
L2 Hit Rate 67.106 % 0.056 5
Mem Pipes Busy 4.686 % 0.001 5
Warp Cycles Per Issued Instruction 28.618 cycle 0.138 5
Warp Cycles Per Executed Instruction 30.124 cycle 0.150 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 23.104 % 0.001 5
Achieved Active Warps Per SM 14.790 warp 0.000 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 (23.1%) 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::to
CPU Time 234113.69 μs
Device Time 39.94 μs
Self CPU Time 37.56 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 234076.13 μs
Device Time 39.94 μs
Self CPU Time 82.83 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 253023.89 μs
Device Time 0.00 μs
Self CPU Time 19388.69 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 233450.54 μs
Device Time 0.00 μs
Self CPU Time 233450.54 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 496471.05 μs
Device Time 22182.02 μs
Self CPU Time 496471.05 μs
Self Device Time 22182.02 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 31239.57 μs
Self CPU Time 0.00 μs
Self Device Time 31239.57 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 19938.90 μs
Device Time 42801.13 μs
Self CPU Time 19938.90 μs
Self Device Time 42801.13 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 63797.97 μs
Device Time 634067.95 μs
Self CPU Time 14060.89 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 49738.76 μs
Device Time 634067.95 μs
Self CPU Time 15607.02 μs
Self Device Time 634067.95 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 634067.95 μs
Self CPU Time 0.00 μs
Self Device Time 634067.95 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 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/b5_s3_sigmoid_min_sync_base/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/b5_s3_sigmoid_min_sync_base/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/b5_s3_sigmoid_min_sync_base/base/base.cu:26:9: warning: result of multiplication in type 'int' is used as a pointer offset after an implicit widening conversion to type 'ptrdiff_t' [bugprone-implicit-widening-of-multiplication-result]
26 | shared_data[tid * 4] = in_vec.x;
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_21/b5_s3_sigmoid_min_sync_base/base/base.cu:26:21: note: make conversion explicit to silence this warning
4 | shared_data[tid * 4] = in_vec.x;
| ^~~~~~~
| static_cast<ptrdiff_t>( )
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_21/b5_s3_sigmoid_min_sync_base/base/base.cu:26:21: note: perform multiplication in a wider type
26 | shared_data[tid * 4] = in_vec.x;
| ^~~
| static_cast<ptrdiff_t>( )
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_21/b5_s3_sigmoid_min_sync_base/base/base.cu:57:21: warning: result of multiplication in type 'int' is used as a pointer offset after an implicit widening conversion to type 'ptrdiff_t' [bugprone-implicit-widening-of-multiplication-result]
57 | out_vec.x = shared_data[tid * 4];
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_21/b5_s3_sigmoid_min_sync_base/base/base.cu:57:33: note: make conversion explicit to silence this warning
57 | out_vec.x = shared_data[tid * 4];
| ^~~~~~~
| static_cast<ptrdiff_t>( )
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_21/b5_s3_sigmoid_min_sync_base/base/base.cu:57:33: note: perform multiplication in a wider type
57 | out_vec.x = shared_data[tid * 4];
| ^~~
| static_cast<ptrdiff_t>( )
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_21/b5_s3_sigmoid_min_sync_base/base/base.cu:77:24: warning: narrowing conversion from 'int64_t' (aka 'long') to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
77 | 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/b5_s3_sigmoid_min_sync_base/base/base.cu:79:5: 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]
79 | 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__, \
| ^