cuda build_error ai_generated true

RuntimeError: Triton compilation failed: LLVM ERROR: out of memory when compiling kernel with large shared memory

ID: cuda/triton-compilation-llvm-crash

Also available as: JSON · Markdown · 中文
72%Fix Rate
83%Confidence
1Evidence
2025-05-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
Triton 2.3.0 active — — —
CUDA 12.5 active — — —
LLVM 18.1.0 active — — —
PyTorch 2.5.0 active — — —

Root Cause

Triton JIT compiler invokes LLVM to optimize kernel code, but the kernel uses excessive shared memory (>48KB per block on most GPUs), causing LLVM's memory allocation for register spilling or optimization to exceed available host memory.

generic

中文

Triton JIT编译器调用LLVM优化内核代码，但内核使用了过多的共享内存（大多数GPU上超过48KB每块），导致LLVM为寄存器溢出或优化分配的内存超过可用主机内存。

Official Documentation

https://triton-lang.org/main/python-api/generated/triton.compiler.CompilationError.html

Workarounds

  1. 80% success Reduce shared memory usage in the Triton kernel: decrease block size or use fewer shared memory allocations. Example: change tl.constexpr BLOCK_SIZE from 128 to 64, and ensure shared memory is not allocated per-thread but per-block. 
    Reduce shared memory usage in the Triton kernel: decrease block size or use fewer shared memory allocations. Example: change tl.constexpr BLOCK_SIZE from 128 to 64, and ensure shared memory is not allocated per-thread but per-block.
  2. 75% success Set environment variable TRITON_MAX_SHARED_MEMORY to a lower value (e.g., 32768 bytes) to force Triton to generate kernels within limits. Command: export TRITON_MAX_SHARED_MEMORY=32768 before running the script. 
    Set environment variable TRITON_MAX_SHARED_MEMORY to a lower value (e.g., 32768 bytes) to force Triton to generate kernels within limits. Command: export TRITON_MAX_SHARED_MEMORY=32768 before running the script.

中文步骤

  1. Reduce shared memory usage in the Triton kernel: decrease block size or use fewer shared memory allocations. Example: change tl.constexpr BLOCK_SIZE from 128 to 64, and ensure shared memory is not allocated per-thread but per-block.
  2. Set environment variable TRITON_MAX_SHARED_MEMORY to a lower value (e.g., 32768 bytes) to force Triton to generate kernels within limits. Command: export TRITON_MAX_SHARED_MEMORY=32768 before running the script.

Dead Ends

Common approaches that don't work:

  1. 90% fail

    The error is not about total system memory but about LLVM's internal allocation limits during compilation; more RAM does not help if the kernel design is flawed.

  2. 95% fail

    Caching is unrelated to compilation memory; it only affects reuse of compiled kernels.