[FIX] Must validate ENV settings or wrong gpu selected by nvidia-smi (a…

…pache#59)

* Raise error if CUDA_DEVICE_ORDER=PCI_BUS_ID env is not applied in multi-gpu sys

* quotes

* protect bad gpu_id

* fix logic

* clean comment

* Update target_detector.py

---------

Co-authored-by: Lei Wang <34334180+LeiWang1999@users.noreply.github.com>

python/bitblas/utils/target_detector.py

@@ -1,6 +1,6 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License.
-
+import os
 import subprocess
 from typing import List
 from thefuzz import process
@@ -26,16 +26,24 @@ def get_gpu_model_from_nvidia_smi(gpu_id: int = 0):
     try:
         # Execute nvidia-smi command to get the GPU name
         output = subprocess.check_output(
-            ["nvidia-smi", f"--id={gpu_id}", "--query-gpu=gpu_name", "--format=csv,noheader"],
+            ["nvidia-smi", "--query-gpu=gpu_name", "--format=csv,noheader"],
             encoding="utf-8",
         ).strip()
     except subprocess.CalledProcessError as e:
         logger.info("nvidia-smi failed with error: %s", e)
         return None
 
-    # Return the name of the first GPU if multiple are present
-    return output.split("\n")[0]
+    gpus = output.split("\n")
+
+    # for multiple gpus, CUDA_DEVICE_ORDER=PCI_BUS_ID must be set to match nvidia-smi or else wrong
+    # gpu is returned for gpu_id
+    if len(gpus) > 0 and os.environ.get("CUDA_DEVICE_ORDER") != "PCI_BUS_ID":
+        raise EnvironmentError("Multi-gpu environment must set `CUDA_DEVICE_ORDER=PCI_BUS_ID`.")
+
+    if gpu_id >= len(gpus) or gpu_id < 0:
+        raise ValueError(f"Passed gpu_id:{gpu_id} but there are {len(gpus)} detected Nvidia gpus.")
 
+    return gpus[gpu_id]
 
 def find_best_match(tags, query):
     """