diff --git a/collective_op_test.py b/collective_op_test.py
new file mode 100755
index 000000000000..87d11ea9d59f
--- /dev/null
+++ b/collective_op_test.py
@@ -0,0 +1,47 @@
+import torch
+import torch.distributed as dist
+import torch_xla
+from typing import List
+from torch_xla import runtime as xr
+import torch_xla.core.xla_model as xm
+import torch_xla.debug.metrics as met 
+
+
+def my_compiler(gm: torch.fx.GraphModule, example_inputs: List[torch.Tensor]):
+  print("my_compiler() called with FX graph:")
+  gm.graph.print_tabular()
+  return gm.forward  # return a python callable
+
+
+
+def dummy_collective_fn(input: torch.Tensor):
+  # output_tensor = xm.all_reduce(xm.REDUCE_SUM, input)
+  # output_tensor = dist.all_reduce(input, dist.ReduceOp.SUM)
+  output_tensor = torch.Tensor([[0, 0, 0, 0]])
+  # dist.all_gather_into_tensor(output_tensor, input, None)
+  dist.all_gather(output_tensor, input, None)
+  return output_tensor
+
+def _mp_fn(index):
+  dist.init_process_group("xla", init_method='xla://')
+  device = xm.xla_device()
+  world_size = xr.world_size()
+  if xm.xla_device_hw(device) not in ('TPU', 'CUDA', 'NEURON'):
+    print(f'skip this test for hw {xm.xla_device_hw(device)}')
+    return
+  ordinal_tensor = torch.tensor([index+1], dtype=torch.float).to(device)
+  met.clear_all()
+  compiled_collective = torch.compile(
+      dummy_collective_fn, backend=my_compiler, dynamic=False)
+  dummy_collective_fn
+  res_tensor = compiled_collective(ordinal_tensor)
+  print(res_tensor)
+  # expected_tensor = torch.tensor(
+  #     [world_size * world_size / 2] * world_size, dtype=torch.float) + 3.0 
+  # torch_xla.sync()
+  # torch.allclose(res_tensor.cpu(), expected_tensor)
+  # assert met.metric_data("ExecuteTime")[0] == 1
+  print(met.metric_data("ExecuteTime"))
+
+if __name__ == '__main__':
+  torch_xla.launch(_mp_fn, args=(), debug_single_process=False)
diff --git a/torch_xla/core/xla_model.py b/torch_xla/core/xla_model.py
index d3c243335f3d..d8a8e72a2e1f 100644
--- a/torch_xla/core/xla_model.py
+++ b/torch_xla/core/xla_model.py
@@ -430,13 +430,15 @@ def all_reduce(reduce_type, inputs, scale=1.0, groups=None, pin_layout=True):
   """
   groups = groups or []
 
-  # No-op if there is only one device
-  if runtime.world_size() == 1 and not xu.getenv_as('XLA_ALWAYS_ALLREDUCE',
-                                                    bool, False):
-    if isinstance(inputs, torch.Tensor):
-      return inputs.clone()
-    else:
-      return inputs
+
+  # PIZ: comment for debug
+  # # No-op if there is only one device
+  # if runtime.world_size() == 1 and not xu.getenv_as('XLA_ALWAYS_ALLREDUCE',
+  #                                                   bool, False):
+  #   if isinstance(inputs, torch.Tensor):
+  #     return inputs.clone()
+  #   else:
+  #     return inputs
 
   if isinstance(inputs, torch.Tensor):
     result = None
diff --git a/torch_xla/csrc/cross_replica_reduces.cpp b/torch_xla/csrc/cross_replica_reduces.cpp
index 6cb689fad655..67d7e4dd5281 100644
--- a/torch_xla/csrc/cross_replica_reduces.cpp
+++ b/torch_xla/csrc/cross_replica_reduces.cpp
@@ -18,6 +18,8 @@
 #include "torch_xla/csrc/xla_graph_executor.h"
 #include "xla/shape_util.h"
 
+#include "torch_xla/csrc/XLANativeFunctions.h" // piz for unsqueeze
+
 namespace torch_xla {
 namespace {
 
@@ -114,6 +116,7 @@ std::shared_ptr<torch::lazy::Value> CreateToken(
 
 at::Tensor all_reduce(const at::Tensor& self, std::string reduceOp,
                       std::string /*group_name*/) {
+  std::cout << "trigger all_reduce lower" << std::endl;
   TORCH_LAZY_FN_COUNTER_TIMED_TRACING("xla::");
   auto self_tensor = bridge::GetXlaTensor(self);
   // TODO(alanwaketan): Use group_name to generate groups. Currently we just
@@ -254,6 +257,24 @@ AllGatherResult BuildAllGather(xla::XlaOp input, xla::XlaOp token, int64_t dim,
   return {all_gather_result, token_handler.GetNewToken(all_gather_result)};
 }
 
+
+
+// function signature should match torch/csrc/distributed/c10d/Functional.cpp
+at::Tensor all_gather_into_tensor(const at::Tensor& self, int64_t group_size, std::string group_name
+                      ) {
+  TORCH_LAZY_FN_COUNTER("xla::");
+  std::cout << "trigger all_gather lower" << std::endl;
+  auto self_tensor = bridge::GetXlaTensor(self);
+  std::vector<int64_t> all_groups(group_size);
+  std::iota(all_groups.begin(), all_groups.end(), 0);
+  auto result = tensor_methods::all_gather(self_tensor, 0, group_size, {all_groups}, true);
+  return bridge::AtenFromXlaTensor(result);
+}
+
+TORCH_LIBRARY_IMPL(_c10d_functional, XLA, m) {
+  m.impl("all_gather_into_tensor", all_gather_into_tensor);
+}
+
 AllGatherResultCoalesced BuildAllGatherCoalesced(
     absl::Span<const xla::XlaOp> inputs, xla::XlaOp token, int64_t dim,
     int64_t shard_count, const std::vector<std::vector<int64_t>>& groups,
diff --git a/torch_xla/distributed/xla_backend.py b/torch_xla/distributed/xla_backend.py
index 31266fa078d4..763b2d5111ee 100644
--- a/torch_xla/distributed/xla_backend.py
+++ b/torch_xla/distributed/xla_backend.py
@@ -46,6 +46,16 @@ def __init__(self, prefix_store, rank, size, timeout):
   def getBackendName(self):
     return 'xla'
 
+
+  def _set_group_name(self, name: str) -> None:
+    self._group_name = name
+ 
+  @property
+  def group_name(self):
+    assert self._group_name
+    return self._group_name
+
+
   def _get_reduce_type(self, reduce_op):
     if reduce_op == dist.ReduceOp.SUM:
       return xm.REDUCE_SUM