cuDNN Frontend API

Introduction

The cuDNN Frontend API is a C++ header-only library that demonstrates how to use the cuDNN C backend API. The cuDNN C backend API is documented in the cuDNN developer guide.

Usage

In order to include the entire library, include the cudnn_frontend header file cudnn_frontend.h into your compilation unit.

Organization

Each cudnnBackendDescriptorType_t documented in the enum is organized into its header file.

cudnn_frontend_Tensor.h -> CUDNN_BACKEND_TENSOR_DESCRIPTOR
cudnn_frontend_ConvDesc.h -> CUDNN_BACKEND_CONVOLUTION_DESCRIPTOR
cudnn_frontend_PointWiseDesc.h -> CUDNN_BACKEND_POINTWISE_DESCRIPTOR
cudnn_frontend_MatMulDesc.h -> CUDNN_BACKEND_MATMUL_DESCRIPTOR
cudnn_frontend_ReductionDesc.h -> CUDNN_BACKEND_REDUCTION_DESCRIPTOR
cudnn_frontend_Operation.h -> CUDNN_BACKEND_OPERATION_*_DESCRIPTOR
cudnn_frontend_OperationGraph.h -> CUDNN_BACKEND_OPERATIONGRAPH_DESCRIPTOR
cudnn_frontend_Heuristics.h -> CUDNN_BACKEND_ENGINEHEUR_DESCRIPTOR
cudnn_frontend_Engine.h -> CUDNN_BACKEND_ENGINE_DESCRIPTOR
cudnn_frontend_EngineConfig.h -> CUDNN_BACKEND_ENGINECFG_DESCRIPTOR
cudnn_frontend_ExecutionPlan.h -> CUDNN_BACKEND_EXECUTION_PLAN_DESCRIPTOR
cudnn_frontend_VariantPack.h -> CUDNN_BACKEND_VARIANT_PACK_DESCRIPTOR

Utility Functions

cudnn_frontend_find_plan.h -> Implements the cudnnFindPlan function
cudnn_frontend_get_plan.h -> Implements the cudnnGetPlan function
cudnn_frontend_Filters.h -> List of helpful utility functions to filter out execution plans

Error Handling

cudnn_frontend_utils.h

Fallback Lists

cudnn_frontend_EngineFallbackList.h -> Provides a fallback engine id if the heuristics do not provide an executable engine.

Samples

Multiple samples of convolution, dgrad, wgrad and convBiasAct are added in samples/test_list.cpp and samples/conv_sample.cpp.
Samples of runtime fusion are added in samples/test_list.cpp and samples/fusion_sample.cpp.

Sample tests are written using the Catch2 C++ test framework.

How to build samples:

 - CUDA_PATH has the cuda installation. 
    - Include files are in CUDA_PATH/include
    - Link files are in CUDA_PATH/lib64
 - CUDNN_WRAP_PATH has the wrapper header files.

 make CUDA_PATH=/usr/local/cuda CUDNN_WRAP_PATH=/usr/local/include/

cudnnFindPlan and cudnnGetPlan:

Prior to cuDNN V8, cuDNN provided cudnnFindConvolution* and cudnnGetConvolution* functions, which provided a way to sample all the algorithms for a given problem and study the run times. This can be further used to cache the best algorithms for a given problem. In cuDNN V8, this has been replaced with cudnnFindPlan and cudnnGetPlan.

In order to use cudnnFindPlan, a user needs to provide:

Source for a pruned list of engineConfigs for the given problem statement
Filter function to Filter out the execution plan based on the prerequisite conditions

The cudnnFindPlan in turn

Creates a set of execution plans that are supported
Execute each filtered plan and ranks them in order of the execution plan runtime

The most common engineConfig generation is the built-in heuristics of cuDNN V8. Generally, this is appended with the fallback list. An example of usage can be seen in run_from_cudnn_find(...) function in conv_sample.cpp.

Errata Filter:

Errata filter gives the cuDNN team an opportunity to block certain faulty kernels from being executed. cuDNN team can eitherprovide a json file which blocks certain engine configs from being executed. The users can augment to this list if they find certain characteristics to be undesirable (Eg. Bad memory access, Execution plan failure). Users can either declare the json file statically or load from a file during runtime using the environment variable "CUDNN_ERRATA_JSON_FILE".

Json format

version             : 1    - Mandatory. Tells the format version of the json.
rules               : []   - Mandatory. Array of rule object which identifies the engine config
rule_id             : ""   - Optional.  Used to uniquely identify a rule. Has no purpose other than being easy to debug.
operation           : ""   - Mandatory. Stringified version of the operation graph.
engine              : ""   - Mandatory. Stringified version of the engine ID.
knob                : ""   - Optional.  Stringified version of the knob. If specified only the engineConfig for the engine matching the knobs will be blocked. Else, all possible combination of knobs for the engine will be blocked.
cudnn_version_start : 0    - Optional. Denotes the cudnn version after which the engine started having issues.
cudnn_version_end   : -1   - Optional. Denotes the cudnn_version when the issue was fixed. "-1" denotes its an ongoing issue.
arch                : ""   - Optional. Architectures where this kernel might be faulty.

PS: The errata filter note is still in beta version. We may add/modify certain features as necessary.

Documentation

Documentation can be found at https://nvidia.github.io/cudnn-frontend/

Feedback

Support, resources, and information about cuDNN can be found online at https://developer.nvidia.com/cudnn.

For questions or to provide feedback, please contact cuDNN@nvidia.com.

jlebar / cudnn-frontend