CUTLASS 4.3.0

[hwu36]

CUTLASS 4.3.1 will be out to fix some CuTe DSL issues very soon.

CuTe DSL

• New features:
  • Supported Apache TVM-FFI for further reduced host runtime overhead for JIT functions, better PyTorch and ML frameworks interopability
  • Added fake tensor and stream to decouple compile jit function with "from_dlpack" flow. Now we no longer require users to have real tensor when compile jit function.
  • Added FastDivmodDivisor with Python operator overloads, new APIs, Cute dialect integration, and optimized static tile scheduler performance for faster index mapping.
  • Added l2 cache evict priority for tma related ops. Users could do fine-grain l2 cache control.
• Debuggability improvements:
  • Supported source location tracking for DSL APIs (Allow tools like nsight profiling to correlate perf metrics with Python source code)
  • Supported dumping PTX and CUBIN code: Hello World Example
• More examples and notebooks to get started with CuTe DSL:
  • Improved performance of elementwise example:
    • Generalize code to handle list of input tensors
    • Generalize TV layout computation to handle different data types
  • Improved Blackwell SM100 persistent dense GEMM with static scheduling:
    • To demonstrate usage of new Pipeline APIs PipelineProducer and PipelineConsumer to simplify code without explicit pipeline state management (Exiting APIs are still maintained)
    • Separated epilogue code for non-TMA and TMA implementation
  • Tutorial for Blackwell GEMM: Basic Blackwell SM100 GEMM
    • Baseline Blackwell GEMM achieves 84% SOL performance with MNK 8K
    • More examples are coming for demo of optimization: Baseline + X
  • Tutorial for Async Pipeline API
  • Reworked elementwise add notebook with more details and detailed explanation about TV layout
    • Updated implementation to handle general data type and multiple inputs
    • Updated explanation for TV layout in simpler language
    • Added visualization of TV Layout with 3rd party utils
  • Benchmark and autotune demonstration
• More examples of authorizing peak-performance kernels:
  • Blackwell SM100 mixed-input GEMM
  • Blackwell SM100 persistent blockwise dense GEMM
  • Blackwell SM100 persistent blockwise contiguous grouped dense GEMM
  • Blackwell SM100 persistent blockwise masked grouped dense GEMM
  • Blackwell SM100 fmha bwd
  • Blackwell SM100 mla
  • Hopper SM90 persistent dense GEMM with static scheduling
  • Blackwell GeForce batched dense GEMM
  • Ampere HSTU Attention
• API updates:
  • Please refer to DSL API changelog for details
• Bug fixings and improvements
  • Add mma_tiler_n=64 and mma_tiler_n=192 support in Blackwell SM100 persistent dense blockscaled GEMM with static scheduling.
  • Fixed TensorSSA.reduce to support static value as initial value
  • Updated docstring for following APIs to be more concise and easier to understand:
    • make_layout_tv
    • is_static
    • PipelineAsync
    • SmemAllocator
  • Fixed documentation for pipeline, utils and cute.math
  • Added overlapping accumulator optimization for block tile N = 256 case for better epilogue latency hiding in Blackwell SM100 persistent dense blockscaled GEMM with static scheduling.
  • Fixed TensorSSA.getitem indexing to match CuTe's indexing convention
  • Fixed an issue with cutlass.max and cutlass.min
  • Fixed an issue with mark_compact_shape_dynamic

CUTLASS C++

• Further enhance Blackwell SM100 Attention kernels in example 77.
  • Add softmax skip correction.
  • Fix a shared memory allocation bug where it needs to opt in maximum dynamics shared memory explicitly once it exceeds 48KB.
  • Fix a dead hang issue caused by early return warp.
• Add support through cmdline argument lists for batch, no_verif, cluster_shape and cluster_shape_fallback in example 89.
• Add Ragged Contiguous Grouped gemm kernel in example 92.
  • This kernel uses a TMA 3D load to load the weights matrix and use the tensormap update method to load activations.
• Add 256x128 tile size support for Hopper SM90 deepgemm in example 67.
  • Performance is optimized to align with Deepseek implementation.
• Simplification of API for MoE gemms.
  • Instead of requiring users to call several cute utilities to set up the stride, API moe_stride_utils is introduced to help setup strides in the kernel.
  • Instead of requiring users to set vectors like problem_shapes_device and problem_shapes_hosts, a new problem shape struct called MoEProblemShape is introduced which takes in max_m, max_n, max_k and counts vector as input and deduce problem shapes internally whenever required.
• Enable GEMM_K = 0 in grouped gemm.
• Optimize group gemm kernels by enabling async TMA desc update.
• Support Blackwell SM100 convolution stream-K kernel.
  • Unit tests: fprop_streamK, dgrad_streamK, wgrad_streamK.
• Add Blackwell SM100 sparse gemm compressor unit tests.
  • Unit tests: compressor_fp16.
  • Add sub-bytes and runtime data type support in compressor unit test testbed.
• Add profiler support for:
  • Blackwell SM100 and SM120 blockscaled sparse kernels.
  • New MoE grouped gemm API.
  • Blackwell SM100 cpasync kernel.
• Fix some kernel issues:
  • Fix a race check issue of Blackwell SM103 kernels by adding missing elect one for prefetch barrier initialization.
  • Allow user to directly specify the number of stages for Hopper sm90 mixed input gemm.
  • Remove warnings caused by cuda vector type alignment setting in CUDA 13.
  • Remove problematic cutlass::int8_t and replace it with int8_t.
  • Fix a few bugs in distributed gemm API and examples.
  • Fix handling negative zero in sparse compressor.
  • Add missing wait_on_dependent_grids for PDL use case.
• Fix some profiler issues:
  • Add some missing reference kernels.
  • Support VoidC reference kernels.
  • Add calculation of scale factor A and B in function bytes_with_problem_shape of block scaled profiler.
  • Fix an issue when epilogue tile N is not divided by default subtile N.
• Various improvements and fixes from the community and CUTLASS team. Thanks to everyone who submitted PRs!
• Optimal code generation with CUDA toolkit versions 13.0U1.

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This discussion was created from the release CUTLASS 4.3.0.