[BUG] Computing result error in cutlass gemm with specfied shape
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Description
when I use cutlass template to write my own gemm kernel, I meet a Internal error, even I follow the settings provided by cutlass profiler.
The full code is as below:
#include <iostream>
#include "cutlass/cutlass.h"
#include "cutlass/gemm/device/gemm.h"
#include "cutlass/util/command_line.h"
#include "cutlass/util/host_tensor.h"
#include "cutlass/util/reference/device/gemm.h"
#include "cutlass/util/reference/host/tensor_compare.h"
#include "cutlass/util/reference/host/tensor_copy.h"
#include "cutlass/util/reference/host/tensor_fill.h"
#include "cutlass/util/tensor_view_io.h"
#include "helper.h"
/////////////////////////////////////////////////////////////////////////////////////////////////
/// Result structure
struct Result
{
double runtime_ms;
double gflops;
cutlass::Status status;
cudaError_t error;
bool passed;
//
// Methods
//
Result(
double runtime_ms = 0,
double gflops = 0,
cutlass::Status status = cutlass::Status::kSuccess,
cudaError_t error = cudaSuccess) : runtime_ms(runtime_ms), gflops(gflops), status(status), error(error), passed(true) {}
};
///////////////////////////////////////////////////////////////////////////////////////////////////
// Command line options parsing
struct Options {
bool help;
cutlass::gemm::GemmCoord problem_size;
int batch_count;
float alpha;
float beta;
bool reference_check;
int iterations;
Options() : help(false),
problem_size({32, 24576, 6144}),
batch_count(1),
reference_check(true),
iterations(20),
alpha(1),
beta() {}
bool valid() {
return true;
}
// Parses the command line
void parse(int argc, char const **args) {
cutlass::CommandLine cmd(argc, args);
if (cmd.check_cmd_line_flag("help")) {
help = true;
}
cmd.get_cmd_line_argument("m", problem_size.m());
cmd.get_cmd_line_argument("n", problem_size.n());
cmd.get_cmd_line_argument("k", problem_size.k());
cmd.get_cmd_line_argument("alpha", alpha);
cmd.get_cmd_line_argument("beta", beta);
cmd.get_cmd_line_argument("iterations", iterations);
}
/// Prints the usage statement.
std::ostream &print_usage(std::ostream &out) const {
out << "14_ampere_tf32_tensorop_gemm example\n\n"
<< "This example uses the CUTLASS Library to execute TF32 tensorop GEMM computations.\n\n"
<< "Options:\n\n"
<< " --help If specified, displays this usage statement.\n\n"
<< " --m=<int> GEMM M dimension\n"
<< " --n=<int> GEMM N dimension\n"
<< " --k=<int> GEMM K dimension\n"
<< " --alpha=<f32> Epilogue scalar alpha\n"
<< " --beta=<f32> Epilogue scalar beta\n"
<< " --iterations=<int> Number of profiling iterations to perform.\n\n";
out << "\nExamples:\n\n"
<< "$ ./examples/14_ampere_tf32_tensorop_gemm/14_ampere_tf32_tensorop_gemm --m=1024 --n=512 --k=1024 \\\n"
<< " --alpha=2 --beta=0.707 \n";
return out;
}
/// Compute performance in GFLOP/s
double gflops(double runtime_s) const {
// Number of real-valued multiply-adds
int64_t fmas = problem_size.product() * batch_count;
// Two flops per multiply-add
return 2.0 * double(fmas) / double(1.0e9) / runtime_s;
}
};
///////////////////////////////////////////////////////////////////////////////////////////////////
// The code section below describes datatype for input, output matrices and computation between
// elements in input matrices.
using ElementAccumulator = cutlass::half_t; // <- data type of accumulator
using ElementComputeEpilogue = ElementAccumulator; // <- data type of epilogue operations
using ElementInputA = cutlass::half_t; // <- data type of elements in input matrix A
using ElementInputB = cutlass::half_t; // <- data type of elements in input matrix B
using ElementOutput = cutlass::half_t; // <- data type of elements in output matrix D
// The code section below describes matrix layout of input and output matrices. Row Colume for A matrix, while Column Major for B and C matrix.
using LayoutInputA = cutlass::layout::RowMajor;
using LayoutInputB = cutlass::layout::RowMajor;
using LayoutOutput = cutlass::layout::ColumnMajor;
// This code section describes whether you want to use tensor cores or regular SIMT cores on GPU SM
using MMAOp = cutlass::arch::OpClassTensorOp;
// This code section describes CUDA SM architecture number
using SmArch = cutlass::arch::Sm80;
// This code section describes the tile size a thread block will compute
using ShapeMMAThreadBlock = cutlass::gemm::GemmShape<256, 128, 32>; // <- threadblock tile M = 128, N = 128, K = 32
// This code section describes tile size a warp will compute
using ShapeMMAWarp = cutlass::gemm::GemmShape<64, 64, 32>; // <- warp tile M = 64, N = 64, K = 32
// This code section describes the size of MMA op
using ShapeMMAOp = cutlass::gemm::GemmShape<16, 8, 8>; // <- MMA Op tile M = 16, N = 8, K = 8
// This code section describes how threadblocks are scheduled on GPU
using SwizzleThreadBlock = cutlass::gemm::threadblock::GemmIdentityThreadblockSwizzle<>;
// This code section describes the epilogue part of the kernel
using EpilogueOp = cutlass::epilogue::thread::LinearCombination<
ElementOutput, // <- data type of output matrix
128 / cutlass::sizeof_bits<ElementOutput>::value, // <- the number of elements per vectorized
// memory access. For a byte, it's 16
// elements. This becomes the vector width of
// math instructions in the epilogue too
ElementAccumulator, // <- data type of accumulator
ElementComputeEpilogue>; // <- data type for alpha/beta in linear combination function
// Number of pipelines you want to use
constexpr int NumStages = 2;
using Gemm = cutlass::gemm::device::Gemm<ElementInputA,
LayoutInputA,
ElementInputB,
LayoutInputB,
ElementOutput,
LayoutOutput,
ElementAccumulator,
MMAOp,
SmArch,
ShapeMMAThreadBlock,
ShapeMMAWarp,
ShapeMMAOp,
EpilogueOp,
SwizzleThreadBlock,
NumStages,
8, // AlignmentA
8>; //AlignmentB
int run(Options &options) {
// Create a tuple of problem size for matrix multiplication
cutlass::gemm::GemmCoord problem_size = options.problem_size;
// Initialize tensors using CUTLASS helper functions
cutlass::HostTensor<ElementInputA, LayoutInputA> tensor_a(
problem_size.mk()); // <- Create matrix A with dimensions M x K
cutlass::HostTensor<ElementInputB, LayoutInputB> tensor_b(
problem_size.kn()); // <- Create matrix B with dimensions K x N
cutlass::HostTensor<ElementOutput, LayoutOutput> tensor_c(
problem_size.mn()); // <- Create matrix C with dimensions M x N
cutlass::HostTensor<ElementOutput, LayoutOutput> tensor_d(
problem_size.mn()); // <- Create matrix D with dimensions M x N used to store output from
// CUTLASS kernel
cutlass::HostTensor<ElementOutput, LayoutOutput> tensor_ref_d(
problem_size.mn()); // <- Create matrix D with dimensions M x N used to store output from
// reference kernel
// Fill input and output matrices on host using CUTLASS helper functions
cutlass::reference::host::TensorFillRandomUniform(
tensor_a.host_view(),
1,
ElementInputA(4),
ElementInputA(-4),
0); // <- Fill matrix A on host with uniform-distribution random data
cutlass::reference::host::TensorFillRandomUniform(
tensor_b.host_view(),
1,
ElementInputB(4),
ElementInputB(-4),
0); // <- Fill matrix B on host with uniform-distribution random data
cutlass::reference::host::TensorFillRandomUniform(
tensor_c.host_view(),
1,
ElementOutput(4),
ElementOutput(-4),
0); // <- Fill matrix C on host with uniform-distribution random data
cutlass::reference::host::TensorFill(
tensor_d.host_view()); // <- fill matrix D on host with zeros
cutlass::reference::host::TensorFill(
tensor_ref_d.host_view()); // <- fill matrix D for reference on host with zeros
// Copy data from host to GPU
tensor_a.sync_device();
tensor_b.sync_device();
tensor_c.sync_device();
tensor_d.sync_device();
tensor_ref_d.sync_device();
// Initialize alpha and beta for dot product computation
ElementComputeEpilogue alpha = ElementComputeEpilogue(options.alpha);
ElementComputeEpilogue beta = ElementComputeEpilogue(options.beta);
// Split K dimension into 1 partitions
int split_k_slices = 1;
// Create a tuple of gemm kernel arguments. This is later passed as arguments to launch
// instantiated CUTLASS kernel
typename Gemm::Arguments arguments{problem_size, // <- problem size of matrix multiplication
tensor_a.device_ref(), // <- reference to matrix A on device
tensor_b.device_ref(), // <- reference to matrix B on device
tensor_c.device_ref(), // <- reference to matrix C on device
tensor_d.device_ref(), // <- reference to matrix D on device
{alpha, beta}, // <- tuple of alpha and beta
split_k_slices}; // <- k-dimension split factor
// Using the arguments, query for extra workspace required for matrix multiplication computation
size_t workspace_size = Gemm::get_workspace_size(arguments);
// Allocate workspace memory
cutlass::device_memory::allocation<uint8_t> workspace(workspace_size);
// Instantiate CUTLASS kernel depending on templates
Gemm gemm_op;
// Check the problem size is supported or not
cutlass::Status status = gemm_op.can_implement(arguments);
CUTLASS_CHECK(status);
// Initialize CUTLASS kernel with arguments and workspace pointer
status = gemm_op.initialize(arguments, workspace.get());
CUTLASS_CHECK(status);
// warmup loop
for (int iter = 0; iter < 5; ++iter) {
// Launch initialized CUTLASS kernel
status = gemm_op();
CUTLASS_CHECK(status);
}
// Result structure
Result result;
// Construct events
cudaEvent_t events[2];
for (auto &event : events) {
result.error = cudaEventCreate(&event);
if (result.error != cudaSuccess) {
std::cerr << "cudaEventCreate() failed: " << cudaGetErrorString(result.error) << std::endl;
return -1;
}
}
// Record an event at the start of a series of GEMMs
result.error = cudaEventRecord(events[0]);
if (result.error != cudaSuccess) {
std::cerr << "cudaEventRecord() failed: " << cudaGetErrorString(result.error) << std::endl;
return -1;
}
// Run profiling loop
for (int iter = 0; iter < options.iterations; ++iter) {
// Launch initialized CUTLASS kernel
status = gemm_op();
// CUDA_CHECK(cudaDeviceSynchronize());
CUTLASS_CHECK(status);
}
// Stop profiling loop
// Record an event when the GEMMs are complete
result.error = cudaEventRecord(events[1]);
if (result.error != cudaSuccess) {
std::cerr << "cudaEventRecord() failed: " << cudaGetErrorString(result.error) << std::endl;
return -1;
}
// Wait for work on the device to complete.
result.error = cudaEventSynchronize(events[1]);
if (result.error != cudaSuccess) {
std::cerr << "cudaEventSynchronize() failed: " << cudaGetErrorString(result.error) << std::endl;
return -1;
}
// Measure elapsed runtime
float runtime_ms = 0;
result.error = cudaEventElapsedTime(&runtime_ms, events[0], events[1]);
if (result.error != cudaSuccess) {
std::cerr << "cudaEventElapsed() failed: " << cudaGetErrorString(result.error) << std::endl;
return -1;
}
// Compute average runtime and GFLOPs.
result.runtime_ms = double(runtime_ms) / double(options.iterations);
result.gflops = options.gflops(result.runtime_ms / 1000.0);
// Cleanup
for (auto event : events) {
(void)cudaEventDestroy(event);
}
// Create instantiation for device reference gemm kernel
cutlass::reference::device::Gemm<ElementInputA,
LayoutInputA,
ElementInputB,
LayoutInputB,
ElementOutput,
LayoutOutput,
ElementComputeEpilogue,
ElementComputeEpilogue> gemm_device;
// Launch device reference gemm kernel
gemm_device(problem_size,
alpha,
tensor_a.device_ref(),
tensor_b.device_ref(),
beta,
tensor_c.device_ref(),
tensor_ref_d.device_ref());
// Wait for kernels to finish
CUDA_CHECK(cudaDeviceSynchronize());
// Copy output data from CUTLASS and reference kernel to host for comparison
tensor_d.sync_host();
tensor_ref_d.sync_host();
// Check if output from CUTLASS kernel and reference kernel are equal or not
bool passed = cutlass::reference::host::TensorEquals(
tensor_d.host_view(),
tensor_ref_d.host_view());
std::cout << "Runtime: " << result.runtime_ms * 1000 << " us" << std::endl;
std::cout << " GFLOPs: " << result.gflops << std::endl;
// if (passed) {
// std::cout << "Runtime: " << result.runtime_ms * 1000 << " us" << std::endl;
// std::cout << " GFLOPs: " << result.gflops << std::endl;
// }
std::cout << (passed ? "Passed" : "Failed") << std::endl;
return (passed ? 0 : -1);
}
int main(int argc, const char **argv) {
bool notSupported = false;
// Ampere Tensor Core operations exposed with mma.sync and ldmatrix are first available
// in CUDA 11.0.
// CUTLASS must be compiled with CUDA 11.0 Toolkit to run these examples.
if (!(__CUDACC_VER_MAJOR__ >= 11)) {
std::cerr << "Ampere Tensor Core operations must be compiled with CUDA 11.0 Toolkit or later." << std::endl;
notSupported = true;
}
cudaDeviceProp props;
cudaError_t error = cudaGetDeviceProperties(&props, 0);
if (error != cudaSuccess) {
std::cerr << "cudaGetDeviceProperties() returned an error: " << cudaGetErrorString(error) << std::endl;
return -1;
}
if (!((props.major * 10 + props.minor) >= 80)) {
std::cerr << "Ampere Tensor Core operations must be run on a machine with compute capability at least 80."
<< std::endl;
notSupported = true;
}
if (notSupported) {
// Returning zero so this test passes on older Toolkits. Its actions are no-op.
return 0;
}
std::cout << "Device Name: " << props.name << std::endl;
std::cout << "Number of Streaming Multiprocessors: " << props.multiProcessorCount << std::endl;
Options options;
options.parse(argc, argv);
if (options.help) {
options.print_usage(std::cout) << std::endl;
return 0;
}
printf("%d x %d x %d Half tensor op Matrix Multiply\n", options.problem_size.m(), options.problem_size.n(), options.problem_size.k());
if (!options.valid()) {
std::cerr << "Invalid problem." << std::endl;
return -1;
}
return run(options);
}
The above setting is provided by cutlass profiler:
Problem ID: 1
Provider: CUTLASS
OperationKind: gemm
Operation: cutlass_tensorop_h1688gemm_256x128_32x2_tt_align8
Status: Success
Verification: ON
Disposition: Passed
reference_device: Passed
cuBLAS: Not run
cuDNN: Not run
Arguments: --gemm_kind=universal --m=32 --n=24576 --k=6144 --A=f16:row --B=f16:row --C=f16:column --D=f16:column \
--alpha=1 --beta=0 --split_k_mode=serial --split_k_slices=1 --batch_count=1 --raster_order=heuristic \
--swizzle_size=1 --op_class=tensorop --accum=f16 --cta_m=256 --cta_n=128 --cta_k=32 --cluster_m=1 --cluster_n=1 \
--cluster_k=1 --stages=2 --warps_m=4 --warps_n=2 --warps_k=1 --inst_m=16 --inst_n=8 --inst_k=8 --min_cc=75 \
--max_cc=1024
Bytes: 303955968 bytes
FLOPs: 9665249280 flops
FLOPs/Byte: 31
Runtime: 0.328755 ms
Memory: 861.069 GiB/s
Math: 29399.5 GFLOP/s
I compiled it with nvcc -std=c++17 -arch=sm_80 -I/xxx/third_party/cutlass/include -I/xxx/third_party/cutlass/tools/util/include -I/xxx/third_party/cutlass/tools/library/include -I/xxx/third_party/cutlass/examples/common -lcublas ./cutlass_gemm.cu --expt-relaxed-constexpr -o cutlass_gemm_example. I use cuda12.6 and RTX 6000 ada GPU.
I'd like to know if this is an issue with the way I'm using it?
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the provided reproducer and the 14_ampere_tf32_tensorop_gemm entry point shown in its usage text, using the specified GEMM shape and CUTLASS configuration. Capture the full internal error and compare the result with the profiler settings; done means the reproducer no longer fails or the failure is isolated to a documented CUTLASS limitation.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- hpc
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 30/100