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29_Softplusoptimized_softplus_cuda_base

Level 1 • Task 29
import torch
import torch.nn as nn
import torch.nn.functional as F


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

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

    Returns:
        torch.Tensor: Output tensor with Softplus applied, same shape as input.
    """
    return F.softplus(x)


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

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

        Returns:
            torch.Tensor: Output tensor with Softplus applied, same shape as input.
        """
        return torch.nn.functional.softplus(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 29 • 29_Softplus)

Rank Kernel Name Runtime (ms) Speedup Native Speedup Compile
🥇 softplus_modular_base_base 0.01 1.16 4.88
🥇 warp_and_alignment_optimized_softplus_edit_1 0.01 1.16 4.88
🥇 branchless_softplus_edit_1 0.01 1.16 4.88
🥇 warp_optimized_softplus_base 0.01 1.16 4.88
5 softplus_unrolled_base_base 0.01 0.99 4.18
5 softplus_coalesced_base 0.01 0.99 4.18
5 softplus_2d_block_thread_base 0.01 0.99 4.18
5 optimized_softplus_cuda_base 0.01 0.99 4.18
5 softplus_coalesced_memory_access_base 0.01 0.99 4.18
5 softplus_tuned_indexing_base_base 0.01 0.99 4.18
5 softplus_blockstride_base 0.01 0.99 4.18
5 softplus_loop_unroll_base_base 0.01 0.99 4.18
5 softplus_branchless_base 0.01 0.99 4.18
5 softplus_blocksize_experiment_base 0.01 0.99 4.18
5 softplus_unrolled_base 0.01 0.99 4.18
5 softplus_constant_memory_base_base 0.01 0.99 4.18
5 optimized_softplus_cuda_base 0.01 0.99 4.18
5 29_Softplus 0.01 0.99 4.18
5 softplus_constant_memory_base 0.01 0.99 4.18
5 optimized_softplus_base 0.01 0.99 4.18
#include <torch/extension.h>
#include <cuda.h>
#include <cuda_runtime.h>
#include <type_traits>

// Store threshold constants in constant memory
__constant__ float c_upper_threshold_float = 20.0f;
__constant__ float c_lower_threshold_float = -20.0f;
__constant__ double c_upper_threshold_double = 20.0;
__constant__ double c_lower_threshold_double = -20.0;

template <typename scalar_t>
__device__ __forceinline__ scalar_t compute_softplus(const scalar_t x) {
    if constexpr (std::is_same<scalar_t, float>::value) {
        if (x > c_upper_threshold_float) return x;
        if (x < c_lower_threshold_float) return expf(x);
        return log1pf(expf(x));
    } else {
        if (x > c_upper_threshold_double) return x;
        if (x < c_lower_threshold_double) return exp(x);
        return log1p(exp(x));
    }
}

template <typename scalar_t>
__global__ void softplus_kernel_optimized(
    const scalar_t* __restrict__ input,
    scalar_t* __restrict__ output,
    const int size) {
    
    int idx = blockIdx.x * blockDim.x + threadIdx.x;
    const int stride = blockDim.x * gridDim.x;

    // Process 4 elements per thread
    #pragma unroll
    for (; idx < size; idx += stride * 4) {
        scalar_t vals[4];
        
        // Coalesced loading of 4 values
        #pragma unroll
        for (int i = 0; i < 4 && idx + i * stride < size; i++) {
            vals[i] = input[idx + i * stride];
        }
        
        // Compute softplus while waiting for memory operations
        #pragma unroll
        for (int i = 0; i < 4 && idx + i * stride < size; i++) {
            output[idx + i * stride] = compute_softplus(vals[i]);
        }
    }
}

torch::Tensor softplus_cuda_forward(torch::Tensor input) {
    auto output = torch::empty_like(input);
    const int size = input.numel();
    const int threads = 256;
    const int blocks = std::min(65535, (size + threads * 4 - 1) / (threads * 4));

    AT_DISPATCH_FLOATING_TYPES(input.scalar_type(), "softplus_forward_cuda", ([&] {
        softplus_kernel_optimized<scalar_t><<<blocks, threads>>>(
            input.data_ptr<scalar_t>(),
            output.data_ptr<scalar_t>(),
            size);
    }));

    return output;
}

PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
    m.def("forward", &softplus_cuda_forward, "Softplus forward (CUDA)");
}
Performance Metrics
Metric Value Unit Variance Samples
Executed Ipc Active 0.866 inst/cycle 0.000 5
Executed Ipc Elapsed 0.430 inst/cycle 0.000 5
Issue Slots Busy 22.506 % 0.122 5
Issued Ipc Active 0.902 inst/cycle 0.000 5
SM Busy 22.506 % 0.122 5
Memory Throughput 233535607385.644 byte/second 27874522734678573056.000 5
Mem Busy 11.086 % 0.075 5
Max Bandwidth 10.306 % 0.055 5
L1/TEX Hit Rate 0.000 % 0.000 5
L2 Hit Rate 67.982 % 0.009 5
Mem Pipes Busy 4.282 % 0.009 5
Warp Cycles Per Issued Instruction 16.540 cycle 0.015 5
Warp Cycles Per Executed Instruction 17.210 cycle 0.016 5
Avg. Active Threads Per Warp 32.000 0.000 5
Avg. Not Predicated Off Threads Per Warp 29.220 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 8.000 block 0.000 5
Block Limit Shared Mem 32.000 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 23.150 % 0.002 5
Achieved Active Warps Per SM 14.814 warp 0.001 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 595067.16 μs
Device Time 40.13 μs
Self CPU Time 39.21 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 595027.95 μs
Device Time 40.13 μs
Self CPU Time 87.34 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 613855.58 μs
Device Time 0.00 μs
Self CPU Time 19252.80 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 594016.16 μs
Device Time 0.00 μs
Self CPU Time 594016.16 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 484352.60 μs
Device Time 21867.05 μs
Self CPU Time 484352.60 μs
Self Device Time 21867.05 μs
CPU Memory Usage 0 B
Device Memory Usage 0 B
Self CPU Memory Usage 0 B
Self Device Memory Usage 0 B
void softplus_kernel_optimized<float>(float const*, float*, int)
CPU Time 0.00 μs
Device Time 35126.31 μs
Self CPU Time 0.00 μs
Self Device Time 35126.31 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 21956.48 μs
Device Time 42068.76 μs
Self CPU Time 21956.48 μs
Self Device Time 42068.76 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 64306.82 μs
Device Time 623313.86 μs
Self CPU Time 11935.58 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 52372.75 μs
Device Time 623313.86 μs
Self CPU Time 17035.89 μs
Self Device Time 623313.86 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 623313.86 μs
Self CPU Time 0.00 μs
Self Device Time 623313.86 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 45323 warnings (45276 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_29/b4_s2_optimized_softplus_cuda/base/base.cu:31:15 bugprone-narrowing-conversions
31 | int idx = blockIdx.x * blockDim.x + threadIdx.x;
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_29/b4_s2_optimized_softplus_cuda/base/base.cu:32:24: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
32 | const int stride = blockDim.x * gridDim.x;
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_29/b4_s2_optimized_softplus_cuda/base/base.cu:55:22: warning: narrowing conversion from 'int64_t' (aka 'long') to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
55 | const int size = input.numel();
| ^
/home/robert_sakana_ai/llm_cuda/experiments/20250202_optimize_b10_s4_e0_sweep/level_1/task_29/b4_s2_optimized_softplus_cuda/base/base.cu:59:5: 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]
59 | AT_DISPATCH_FLOATING_TYPES(input.scalar_type(), "softplus_forward_cuda", ([&] {
| ^
/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__, \
| ^