[Common] Default CUDA_HOME to /usr/local/cuda when dynamically loading cuDNN and NVRTC (#1183)

Defaulted CUDA_HOME/CUDA_PATH to /usr/local/cuda when attempting to dynamically load cuDNN and NVRTC
Signed-off-by: Alp Dener <adener@nvidia.com>

transformer_engine/common/__init__.py

@@ -47,20 +47,20 @@ def _get_sys_extension():
 
 def _load_cudnn():
     """Load CUDNN shared library."""
-
+    # Attempt to locate cuDNN in Python dist-packages
     lib_path = glob.glob(
         os.path.join(
             sysconfig.get_path("purelib"),
             f"nvidia/cudnn/lib/libcudnn.{_get_sys_extension()}.*[0-9]",
         )
     )
-
     if lib_path:
         assert (
             len(lib_path) == 1
         ), f"Found {len(lib_path)} libcudnn.{_get_sys_extension()}.x in nvidia-cudnn-cuXX."
         return ctypes.CDLL(lib_path[0], mode=ctypes.RTLD_GLOBAL)
 
+    # Attempt to locate cuDNN in CUDNN_HOME or CUDNN_PATH, if either is set
     cudnn_home = os.environ.get("CUDNN_HOME") or os.environ.get("CUDNN_PATH")
     if cudnn_home:
         libs = glob.glob(f"{cudnn_home}/**/libcudnn.{_get_sys_extension()}*", recursive=True)
@@ -68,13 +68,14 @@ def _load_cudnn():
         if libs:
             return ctypes.CDLL(libs[0], mode=ctypes.RTLD_GLOBAL)
 
-    cuda_home = os.environ.get("CUDA_HOME") or os.environ.get("CUDA_PATH")
-    if cuda_home:
+    # Attempt to locate cuDNN in CUDA_HOME, CUDA_PATH or /usr/local/cuda
+    cuda_home = os.environ.get("CUDA_HOME") or os.environ.get("CUDA_PATH") or "/usr/local/cuda"
     libs = glob.glob(f"{cuda_home}/**/libcudnn.{_get_sys_extension()}*", recursive=True)
     libs.sort(reverse=True, key=os.path.basename)
     if libs:
         return ctypes.CDLL(libs[0], mode=ctypes.RTLD_GLOBAL)
 
+    # If all else fails, assume that it is in LD_LIBRARY_PATH and error out otherwise
     return ctypes.CDLL(f"libcudnn.{_get_sys_extension()}", mode=ctypes.RTLD_GLOBAL)
 
 
@@ -91,14 +92,15 @@ def _load_library():
 
 def _load_nvrtc():
     """Load NVRTC shared library."""
-    cuda_home = os.environ.get("CUDA_HOME") or os.environ.get("CUDA_PATH")
-    if cuda_home:
+    # Attempt to locate NVRTC in CUDA_HOME, CUDA_PATH or /usr/local/cuda
+    cuda_home = os.environ.get("CUDA_HOME") or os.environ.get("CUDA_PATH") or "/usr/local/cuda"
     libs = glob.glob(f"{cuda_home}/**/libnvrtc.{_get_sys_extension()}*", recursive=True)
     libs = list(filter(lambda x: not ("stub" in x or "libnvrtc-builtins" in x), libs))
     libs.sort(reverse=True, key=os.path.basename)
     if libs:
         return ctypes.CDLL(libs[0], mode=ctypes.RTLD_GLOBAL)
 
+    # Attempt to locate NVRTC via ldconfig
     libs = subprocess.check_output("ldconfig -p | grep 'libnvrtc'", shell=True)
     libs = libs.decode("utf-8").split("\n")
     sos = []
@@ -109,6 +111,8 @@ def _load_nvrtc():
             sos.append(lib.split(">")[1].strip())
     if sos:
         return ctypes.CDLL(sos[0], mode=ctypes.RTLD_GLOBAL)
+
+    # If all else fails, assume that it is in LD_LIBRARY_PATH and error out otherwise
     return ctypes.CDLL(f"libnvrtc.{_get_sys_extension()}", mode=ctypes.RTLD_GLOBAL)