improve setting of NCCL_P2P_DISABLE on runpod (#3132) [skip ci]

* improve setting of NCCL_P2P_DISABLE on runpod

* use recs from review

src/axolotl/utils/environment.py

@@ -2,6 +2,8 @@
 utils to get GPU info for the current environment
 """
 
+import os
+import subprocess  # nosec B404
 from importlib.metadata import version
 
 from accelerate.utils.environment import (
@@ -14,6 +16,8 @@ from packaging.version import Version, parse
 def check_cuda_p2p_ib_support():
     if not accelerate_check_cuda_p2p_ib_support():
         return False
+    if not check_runpod_p2p_support():
+        return False
     unsupported_devices = {"RTX 6000 Ada", "L40S"}
     try:
         device_names, device_count = get_gpu_info()
@@ -29,6 +33,39 @@ def check_cuda_p2p_ib_support():
     return True
 
 
+def check_runpod_p2p_support() -> bool:
+    if "RUNPOD_GPU_COUNT" not in os.environ:
+        return True
+    try:
+        gpu_count = int(os.environ.get("RUNPOD_GPU_COUNT", "1"))
+    except ValueError:
+        return True
+    if gpu_count >= 2:
+        # run `nvidia-smi topo -p2p n` and inspect the GPU0 row
+        try:
+            result = subprocess.run(  # nosec B603 B607
+                ["nvidia-smi", "topo", "-p2p", "n"],
+                check=True,
+                capture_output=True,
+                text=True,
+                timeout=5,
+            )
+        except (
+            subprocess.CalledProcessError,
+            FileNotFoundError,
+            subprocess.TimeoutExpired,
+        ):
+            return True  # fail-open if detection fails
+        output_lines = result.stdout.strip().split("\n")
+        # filter rows that start with "GPU0" (avoid header row)
+        gpu0_rows = [line for line in output_lines if line.lstrip().startswith("GPU0")]
+        if not gpu0_rows:
+            return True
+        # consider P2P supported if any OK is present in the GPU0 row
+        return "OK" in gpu0_rows[-1]
+    return True
+
+
 def get_package_version(package: str) -> Version:
     version_str = version(package)
     return parse(version_str)