From 5a5cece5616d930ea9651b831e6b4d2efa074351 Mon Sep 17 00:00:00 2001
From: Xiaoyu Zhang <35585791+BBuf@users.noreply.github.com>
Date: Thu, 8 Jan 2026 11:08:34 +0800
Subject: [PATCH] [Diffusion] clean useless and buggy set_seq_parallel_pg in
 yunchang (#16669)

---
 .../runtime/distributed/yunchang.py           | 62 -------------------
 1 file changed, 62 deletions(-)

diff --git a/python/sglang/multimodal_gen/runtime/distributed/yunchang.py b/python/sglang/multimodal_gen/runtime/distributed/yunchang.py
index 241e57e8c..567c9b30a 100644
--- a/python/sglang/multimodal_gen/runtime/distributed/yunchang.py
+++ b/python/sglang/multimodal_gen/runtime/distributed/yunchang.py
@@ -22,68 +22,6 @@ class ProcessGroupSingleton(Singleton):
 PROCESS_GROUP = ProcessGroupSingleton()
 
 
-def set_seq_parallel_pg(
-    sp_ulysses_degree, sp_ring_degree, rank, world_size, use_ulysses_low=True
-):
-    """
-    sp_ulysses_degree x sp_ring_degree = seq_parallel_degree
-    (ulysses_degree, dp_degree)
-    """
-    sp_degree = sp_ring_degree * sp_ulysses_degree
-    dp_degree = world_size // sp_degree
-
-    assert (
-        world_size % sp_degree == 0
-    ), f"world_size {world_size} % sp_degree {sp_ulysses_degree} == 0"
-
-    num_ulysses_pgs = sp_ring_degree  # world_size // sp_ulysses_degree
-    num_ring_pgs = sp_ulysses_degree  # world_size // sp_ring_degree
-
-    if use_ulysses_low:
-        for dp_rank in range(dp_degree):
-            offset = dp_rank * sp_degree
-            for i in range(num_ulysses_pgs):
-                ulysses_ranks = list(
-                    range(
-                        i * sp_ulysses_degree + offset,
-                        (i + 1) * sp_ulysses_degree + offset,
-                    )
-                )
-                group = torch.distributed.new_group(ulysses_ranks)
-                if rank in ulysses_ranks:
-                    ulyssess_pg = group
-
-            for i in range(num_ring_pgs):
-                ring_ranks = list(range(i + offset, sp_degree + offset, num_ring_pgs))
-                group = torch.distributed.new_group(ring_ranks)
-                if rank in ring_ranks:
-                    ring_pg = group
-
-    else:
-        for dp_rank in range(dp_degree):
-            offset = dp_rank * sp_degree
-            for i in range(num_ring_pgs):
-                ring_ranks = list(
-                    range(
-                        i * sp_ring_degree + offset, (i + 1) * sp_ring_degree + offset
-                    )
-                )
-                group = torch.distributed.new_group(ring_ranks)
-                if rank in ring_ranks:
-                    ring_pg = group
-
-            for i in range(num_ulysses_pgs):
-                ulysses_ranks = list(
-                    range(i + offset, sp_degree + offset, num_ulysses_pgs)
-                )
-                group = torch.distributed.new_group(ulysses_ranks)
-                if rank in ulysses_ranks:
-                    ulyssess_pg = group
-
-    PROCESS_GROUP.ULYSSES_PG = ulyssess_pg
-    PROCESS_GROUP.RING_PG = ring_pg
-
-
 def set_seq_parallel_pg_by_sp_groups(
     sp_ulysses_degree,
     sp_ring_degree,