Auto-detect current GPU architecture at install time

conda/core_dev.yml

@@ -12,6 +12,7 @@ dependencies:
   - pre-commit
   - pyarrow>=5
   - pydata-sphinx-theme
+  - pynvml
   - pytest
   - python>=3.7
   - setuptools>=60

install.py

@@ -660,6 +660,26 @@ def install(
                 )
         dump_json_config(cuda_config, cuda_dir)
 
+        arch_config = os.path.join(legate_core_dir, ".arch.json")
+        if arch is None:
+            arch = load_json_config(arch_config)
+            if arch is None:
+                try:
+                    import pynvml
+
+                    pynvml.nvmlInit()
+                    major, minor = pynvml.nvmlDeviceGetCudaComputeCapability(
+                        pynvml.nvmlDeviceGetHandleByIndex(0)
+                    )
+                    arch = f"{major}{minor}"
+                    pynvml.nvmlShutdown()
+                except Exception as exc:
+                    raise Exception(
+                        "Could not auto-detect CUDA GPU architecture, please "
+                        "specify the target architecture using --arch"
+                    ) from exc
+        dump_json_config(arch_config, arch)
+
         nccl_config = os.path.join(legate_core_dir, ".nccl.json")
         if nccl_dir is None:
             nccl_dir = load_json_config(nccl_config)
@@ -866,7 +886,7 @@ def driver():
         dest="arch",
         action="store",
         required=False,
-        default="volta",
+        default=None,
         help="Specify the target GPU architecture.",
     )
     parser.add_argument(