platform: Remove NCCL_NETDEVS_POLICY setting from P5en/P6-B200

Remove NCCL_NETDEVS_POLICY=max:1 setting from the default environment
variables for P5en/P6-B200 instances. This configuration requires
additional testing and optimization before being included as a default
setting.

This reverts commit 2474f73.

Signed-off-by: Mozar Huang <[email protected]>

Author: mozarhua

src/platform-aws.cpp

@@ -70,12 +70,6 @@
  *
  *    The NVLSTree chunk size can not be larger than the NVLS chunk size,
  *    so we ensure both are set to 512KiB.
- *
- *  * NCCL v2.28.3 introduced NCCL_NETDEVS_POLICY to control how NET devices
- *    are assigned to GPUs. In platforms having multiple GPUs and NICs per
- *    PCIe switch, setting this policy will change the traffic distribution
- *    across the NICs, depending on the collective type as well as other
- *    factors. Thus, the best policy setting may vary per platform.
  */
 static struct ec2_platform_data platform_data_map[] = {
 	{
@@ -145,41 +139,13 @@ static struct ec2_platform_data platform_data_map[] = {
 			{ "NCCL_NET_FORCE_FLUSH", "0" },
 		},
 	},
-	{
-		.name = "p5en/p6-b200",
-		.regex = "^(p5en|p6-b200).*",
-		.topology = NULL,
-		.default_dup_conns = 0,
-		.latency = 35.0,
-		.gdr_required = true,
-		.default_protocol = PROTOCOL::RDMA,
-		.domain_per_thread = true,
-		/*
-		 * Note: Based on empirical testing, setting the
-		 * NCCL_NETDEVS_POLICY=max:1 gives optimal performance
-		 * on platforms with 2 GPUs and 2 NICs per PCIe switch,
-		 * such as P5en and P6-B200.
-		 */
-		.env = {
-			{ "NCCL_BUFFSIZE", "8388608" },
-			{ "NCCL_P2P_NET_CHUNKSIZE", "524288" },
-			{ "NCCL_NVLSTREE_MAX_CHUNKSIZE", "524288" },
-			{ "NCCL_NVLS_CHUNKSIZE", "524288" },
-			{ "NCCL_NET_FORCE_FLUSH", "0" },
-			{ "NCCL_NETDEVS_POLICY", "max:1" },
-		},
-	},
 	{
 		.name = "p-series",
 		/*
 		 * While the regex will match against P5 and later
-		 * instance families, we expect this to apply to
-		 * P6e-GB200 and later, due to previous entries to
-		 * match P5, P5e, P5en, and P6-B200.
-		 *
-		 * Note: Need to revisit NCCL_NETDEVS_POLICY when
-		 * platforms have different topology or major
-		 * hardware changes.
+		 * instance families, we expect this to only apply
+		 * to P5en and later, due to previous entries to
+		 * match P5 and P5e.
 		 */
 		.regex = "^p([5-9]|[0-9]{2,}).*",
 		.topology = NULL,

tests/unit/aws_platform_mapper.cpp

@@ -60,9 +60,8 @@ static int check_known_platforms(void)
 	ret += check_value(platform_data_list, len, "p5.4xlarge", "p5.4xlarge");
 	ret += check_value(platform_data_list, len, "p5.48xlarge", "p5/p5e");
 	ret += check_value(platform_data_list, len, "p5e.48xlarge", "p5/p5e");
-	ret += check_value(platform_data_list, len, "p5en.48xlarge", "p5en/p6-b200");
-	ret += check_value(platform_data_list, len, "p6-b200.48xlarge", "p5en/p6-b200");
-	ret += check_value(platform_data_list, len, "p6e-gb200.36xlarge", "p-series");
+	ret += check_value(platform_data_list, len, "p5en.48xlarge", "p-series");
+	ret += check_value(platform_data_list, len, "p6-b200.48xlarge", "p-series");
 	ret += check_value(platform_data_list, len, "g5.48xlarge", "g5.48xlarge");
 	ret += check_value(platform_data_list, len, "g6.16xlarge", NULL);