[CI][AMD][BugFix] Update wvSplitK (and other skinny_gemm wrappers) to ensure tensors passed will be made contiguous for the kernel (#32831)

Signed-off-by: Randall Smith <ransmith@amd.com>
Co-authored-by: Randall Smith <ransmith@amd.com>

csrc/rocm/skinny_gemms.cu

@@ -13,6 +13,13 @@
 #include "dispatch_utils.h"
 #include "quantization/w8a8/fp8/common.cuh"
 
+// TODO(rasmith): The kernels in this file are susceptible to integer overflow
+// issues, do not take strides, and are unable to handle PyTorch tensors that
+// return is_contiguous() as False (the tensors may actually be contiguous
+// in memory).
+//
+// However, it may be possible to fix these kernels to handle both issues.
+
 #if defined(__HIPCC__) && \
     (defined(__gfx90a__) || defined(__gfx942__) || defined(__gfx950__))
   #define __HIP__GFX9__

vllm/_custom_ops.py

@@ -2027,20 +2027,35 @@ def selective_scan_fwd(
     )
 
 
+# NOTE: The wvSplitK kernel (and all of the kernels in skinny_gemms.cu)
+# are unable to properly handle non-contiguous
+# tensors.  It might be a good TODO(rasmith) to augment these kernels
+# to be able to handle non-contiguous kernels for better performance.
+def rocm_enforce_contiguous_skinny_gemm_inputs(
+    a: torch.Tensor, b: torch.Tensor
+) -> tuple[torch.Tensor, torch.Tensor]:
+    a = a.contiguous()  # no-op if already contiguous, else clone
+    b = b.contiguous()  # no-op if already contiguous, else clone
+    return a, b
+
+
 # ROCm skinny gemms
 def LLMM1(a: torch.Tensor, b: torch.Tensor, rows_per_block: int) -> torch.Tensor:
+    a, b = rocm_enforce_contiguous_skinny_gemm_inputs(a, b)
     return torch.ops._rocm_C.LLMM1(a, b, rows_per_block)
 
 
 def wvSplitK(
     a: torch.Tensor, b: torch.Tensor, cu_count: int, bias: torch.Tensor = None
 ) -> torch.Tensor:
+    a, b = rocm_enforce_contiguous_skinny_gemm_inputs(a, b)
     return torch.ops._rocm_C.wvSplitK(a, b, bias, cu_count)
 
 
 def wvSplitKrc(
     a: torch.Tensor, b: torch.Tensor, cu_count: int, bias: torch.Tensor = None
 ) -> torch.Tensor:
+    a, b = rocm_enforce_contiguous_skinny_gemm_inputs(a, b)
     return torch.ops._rocm_C.wvSplitKrc(a, b, bias, cu_count)
 
 
@@ -2053,6 +2068,7 @@ def wvSplitKQ(
     cu_count: int,
     bias: torch.Tensor = None,
 ) -> torch.Tensor:
+    a, b = rocm_enforce_contiguous_skinny_gemm_inputs(a, b)
     out = torch.empty((b.shape[0], a.shape[0]), dtype=out_dtype, device=b.device)
     torch.ops._rocm_C.wvSplitKQ(a, b, bias, out, scale_a, scale_b, cu_count)
     return out