diff --git a/README.md b/README.md
index fb0429bd..e943eeb8 100644
--- a/README.md
+++ b/README.md
@@ -69,7 +69,30 @@ How to setup Tutel MoE for Pytorch and [run examples](tutel/examples), or [enabl
 
 ```
 
-How to import Tutel-optimized MoE in Pytorch:
+#### How to convert checkpoint files that adapt to different distributed world sizes:
+```
+# Firstly, using 2 GPUs to train a model with 16 global experts (each GPU holds 8 local experts), saving checkpoint files in the end:
+mpiexec -bind-to none -host localhost -x LOCAL_SIZE=2 python3 -m tutel.launcher.run -m tutel.examples.helloworld --num_local_experts=8 --checkpoint=./states/{rank}-of-{size}.ckpt --device=cuda
+
+# Secondly, convert the checkpoint files (based on 2 GPUs) into a single checkpoint file containing all parameters:
+python3 -m tutel.checkpoint.gather --inputs=./states/{rank}-of-{size}.ckpt --input_size=2 --output ./model-synthetis.ckpt
+
+# Optionally, you can test the synthetis checkpoint using single CPU device, note that there will be 16 experts locally:
+python3 -m tutel.examples.helloworld --num_local_experts=16 --checkpoint=./model-synthetis.ckpt --device=cpu --eval
+
+# Next, convert the synthetis checkpoint file that adapts to distributed training using 8 GPUs:
+python3 -m tutel.checkpoint.scatter --input=./model-synthetis.ckpt --output_size=8 --outputs=./adapted-for-8-gpus/{rank}-of-{size}.ckpt
+
+# Then, using generated checkpoint files to train/eval using 8 GPUs, note that there will be 2 local experts this time:
+mpiexec -bind-to none -host localhost -x LOCAL_SIZE=8 python3 -m tutel.launcher.run -m tutel.examples.helloworld --num_local_experts=2 --checkpoint=./adapted-for-8-gpus/{rank}-of-{size}.ckpt --device=cuda
+
+# Similarly, the convertion tool also supports X global experts adapting to Y GPUs, where Y % X == 0, making num_local_experts to be -Y / X.
+python3 -m tutel.checkpoint.scatter --input=./model-synthetis.ckpt --output_size=32 --outputs=./adapted-for-32-gpus/{rank}-of-{size}.ckpt
+mpiexec -bind-to none -host localhost -x LOCAL_SIZE=32 python3 -m tutel.launcher.run -m tutel.examples.helloworld --num_local_experts=-2 --checkpoint=./adapted-for-32-gpus/{rank}-of-{size}.ckpt --device=cuda
+
+```
+
+#### How to import Tutel-optimized MoE in Pytorch:
 ```
 # Input Example:
 import torch
@@ -104,7 +127,7 @@ y = moe_layer(x)
 print(y)
 ```
 
-Usage of MOELayer:
+#### Usage of MOELayer:
 ```
 * Usage of MOELayer Args:
 
@@ -130,7 +153,7 @@ Usage of MOELayer:
         activation_fn    : the custom-defined activation function between two linear layers (used for type == 'ffn' only)
 ```
 
-For Deepspeed MoE Acceleration (Deepspeed MoE Top-1 Gate has integrated Tutel acceleration):
+#### For Deepspeed MoE Acceleration (Deepspeed MoE Top-1 Gate has integrated Tutel acceleration):
 ```sh
 # Without Tutel optimization:
 python3 -m tutel.examples.helloworld_deepspeed --top=1
@@ -139,25 +162,6 @@ python3 -m tutel.examples.helloworld_deepspeed --top=1
 python3 -m tutel.examples.helloworld_deepspeed --top=1 --use_tutel
 ```
 
-
-### Single-GPU Throughput (batches/sec) with default settings on NVIDIA A100 (40GB):
-| batch-size | helloworld (top2) | helloworld_ddp (top2) | helloworld_deepspeed (top2) |
-| :--------: | :--------: | :------------: | :------------------: |
-| 8  | 672.75 | 672.24 | 188.27 |
-| 16 | 715.86 | 714.95 | 115.43 |
-| 24 | 725.95 | 725.04 | 81.02 |
-| 32 | 729.02 | 729.02 | OOM |
-| 64 | 687.92 | 686.31 | OOM |
-| 128 | 619.75 | 619.03 | OOM |
-| 256 | 577.08 | 577.49 | OOM |
-
-How to reproduce these results:
-```shell
-$ python3 -m tutel.examples.helloworld --batch_size=<batch_size>
-$ python3 -m tutel.examples.helloworld_ddp --batch_size=<batch_size>
-$ python3 -m tutel.examples.helloworld_deepspeed --batch_size=<batch_size>
-```
-
 ## Reference
 You can consult this [paper](https://arxiv.org/pdf/2206.03382.pdf) below to get to know more technical details about Tutel:
 ```
diff --git a/setup.py b/setup.py
index 99ec8192..4fed37cf 100755
--- a/setup.py
+++ b/setup.py
@@ -72,12 +72,6 @@ def install(use_cuda, use_nccl):
             ext_libs += ['nccl']
         ext_args += ['-DUSE_NCCL']
 
-    for folder in ('build', 'dist',):
-        try:
-            shutil.rmtree(os.path.join(root_path, folder))
-        except:
-            pass
-
     setup(
         name='tutel',
         version='0.1',
diff --git a/tutel/checkpoint/__init__.py b/tutel/checkpoint/__init__.py
new file mode 100644
index 00000000..c45e0a75
--- /dev/null
+++ b/tutel/checkpoint/__init__.py
@@ -0,0 +1,3 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
diff --git a/tutel/checkpoint/gather.py b/tutel/checkpoint/gather.py
new file mode 100644
index 00000000..70bd9f16
--- /dev/null
+++ b/tutel/checkpoint/gather.py
@@ -0,0 +1,60 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+import os
+import argparse
+import torch
+import re
+
+from tutel.system import apply_rank_size_from_pattern
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--input_size', type=int, required=True)
+    parser.add_argument('--inputs', type=str, required=True)
+    parser.add_argument('--output', type=str, required=True)
+    args = parser.parse_args()
+    args.size = args.input_size
+
+    mutate_size, expert_dict = {}, {}
+
+    input_file = apply_rank_size_from_pattern(args.inputs, rank=0, size=args.size)
+    state_dict = torch.load(input_file, map_location=torch.device('cpu'))
+    for k in state_dict:
+        if k.endswith('._num_global_experts'):
+             entry = k[:k.rindex('.')] + '.experts.'
+             mutate_size[entry] = int(state_dict[k])
+
+    if not mutate_size:
+        raise Exception('No any Tutel MoE layer is found, as the provided checkpoint may be in legacy format. You need to reload this legacy checkpoint by corresponding application, re-checkpoint model\'s state_dict and get the latest format.')
+
+    for rank in range(args.size):
+        input_file = apply_rank_size_from_pattern(args.inputs, rank=rank, size=args.size)
+        state_dict = torch.load(input_file, map_location=torch.device('cpu'))
+        for k in state_dict:
+            for e in mutate_size:
+                if k.startswith(e):
+                    expert_dict[k] = expert_dict.get(k, [mutate_size[e],]) + [state_dict[k],]
+
+    expert_dict = [(i, k, expert_dict[k]) for i, k in enumerate(expert_dict)]
+    for i, k, v in expert_dict:
+        num_global_experts, pieces = v[0], v[1:]
+        if num_global_experts % args.size == 0:
+            expert_dict[i] = torch.concat(pieces, dim=0).contiguous().clone()
+            assert expert_dict[i].size(0) == num_global_experts, "Unexpected group size of expert with num_global_experts: %d v.s. %d. Maybe you set a wrong --size value." % (expert_dict[i].size(0), num_global_experts)
+        elif args.size % num_global_experts == 0:
+            expert_dict[i] = torch.concat(pieces, dim=0).contiguous()
+            expert_dict[i] = expert_dict[i].view([num_global_experts, -1] + list(expert_dict[i].shape)[2:]).clone()
+        else:
+            raise Exception(f'Neither of "global_experts({num_global_experts}) / args.size({args.size})" nor "args.size({args.size}) / global_experts({num_global_experts})" is evenly divisible.')
+        expert_dict[i] = (k, expert_dict[i])
+
+    expert_dict = dict(expert_dict)
+    for k in state_dict:
+        if k in expert_dict:
+            state_dict[k] = expert_dict[k]
+    torch.save(state_dict, args.output)
+
+if __name__ == "__main__":
+    main()
+
diff --git a/tutel/checkpoint/scatter.py b/tutel/checkpoint/scatter.py
new file mode 100644
index 00000000..89e671ef
--- /dev/null
+++ b/tutel/checkpoint/scatter.py
@@ -0,0 +1,61 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+import os
+import argparse
+import torch
+import re
+
+from tutel.system import apply_rank_size_from_pattern
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--output_size', type=int, required=True)
+    parser.add_argument('--input', type=str, required=True)
+    parser.add_argument('--outputs', type=str, required=True)
+    args = parser.parse_args()
+    args.size = args.output_size
+
+    state_dict = torch.load(args.input, map_location=torch.device('cpu'))
+    mutate_size, expert_dict = {}, {}
+
+    for k in state_dict:
+        if k.endswith('._num_global_experts'):
+            entry = k[:k.rindex('.')] + '.experts.'
+            mutate_size[entry] = int(state_dict[k])
+
+    if not mutate_size:
+        raise Exception('No any Tutel MoE layer is found, as the provided checkpoint may be in legacy format. You need to reload this legacy checkpoint by corresponding application, re-checkpoint model\'s state_dict and get the latest format.')
+
+    for k in state_dict:
+        for e in mutate_size:
+            if k.startswith(e):
+                state = state_dict[k]
+                shape = state.shape
+                if shape[0] % args.size == 0:
+                    state = state.view([args.size, shape[0] // args.size] + list(shape)[1:])
+                elif args.size % shape[0] == 0:
+                    divisor = args.size // shape[0]
+                    for i in range(1, len(shape)):
+                        if shape[i] <= 1:
+                            continue
+                        assert shape[i] % divisor == 0, f"The second non-squeezable dimension is to be sliced to {divisor} pieces from an parameter of shape {shape}, which isn't divisible evenly."
+                    state = state.view([args.size,] + list(shape)[1:i] + [shape[i] // divisor,] + list(shape)[i+1:])
+                else:
+                    raise Exception(f'Neither of "global_experts({int(shape[0])}) / args.size({args.size})" nor "args.size({args.size}) / global_experts({int(shape[0])})" is evenly divisible.')
+                expert_dict[k] = state
+
+    for rank in range(args.size):
+        generate_dict = dict()
+        for k in state_dict:
+            if k not in expert_dict:
+                generate_dict[k] = state_dict[k]
+            else:
+                generate_dict[k] = expert_dict[k][rank, :].contiguous().clone()
+
+        output_file = apply_rank_size_from_pattern(args.outputs, rank=rank, size=args.size)
+        torch.save(generate_dict, output_file)
+
+if __name__ == "__main__":
+    main()
+
diff --git a/tutel/examples/helloworld.py b/tutel/examples/helloworld.py
index cd0b696f..11d5535f 100755
--- a/tutel/examples/helloworld.py
+++ b/tutel/examples/helloworld.py
@@ -30,7 +30,7 @@
 parser.add_argument('--allreduce_degree', type=int, default=1)
 parser.add_argument('--num_steps', type=int, default=100)
 parser.add_argument('--parallel_type', type=str, default='auto')
-parser.add_argument('--save_load_checkpoint', default=False, action='store_true')
+parser.add_argument('--checkpoint_path', type=str, default='')
 parser.add_argument('--device', type=str, default='cuda' if torch.cuda.is_available() else 'cpu')
 parser.add_argument('--use_2dh', default=False, action='store_true')
 parser.add_argument('--eval', default=False, action='store_true')
@@ -89,12 +89,12 @@ def forward(self, input):
 model = ExampleModel().to(device)
 dist_print(model)
 
-if args.save_load_checkpoint:
-    checkpoint_path = './distributed-hellworld-%d-in-%d.ckpt' % (parallel_env.global_rank, parallel_env.global_size)
+if args.checkpoint_path:
+    checkpoint_path = system.apply_rank_size_from_pattern(args.checkpoint_path, rank=parallel_env.global_rank, size=parallel_env.global_size)
     if os.path.exists(checkpoint_path):
         model.load_state_dict(torch.load(checkpoint_path))
     else:
-        print('Checkpoint not loaded: file `%s` is not found' % checkpoint_path)
+        print('Checkpoint not loaded: file `%s` is not found. Will train the model from start.' % checkpoint_path)
 
 optimizer = torch.optim.SGD(model.parameters(), lr=1e-5)
 
@@ -145,5 +145,5 @@ def forward(self, input):
 average_time /= 10
 dist_print('\n[Summary] Average synchronized step_time = %s sec.' % average_time)
 
-if args.save_load_checkpoint:
+if args.checkpoint_path:
     torch.save(model.state_dict(), checkpoint_path)
diff --git a/tutel/examples/helloworld_ddp_tutel.py b/tutel/examples/helloworld_ddp_tutel.py
index fdb1af43..df36d72d 100755
--- a/tutel/examples/helloworld_ddp_tutel.py
+++ b/tutel/examples/helloworld_ddp_tutel.py
@@ -30,7 +30,6 @@
 parser.add_argument('--allreduce_degree', type=int, default=1)
 parser.add_argument('--num_steps', type=int, default=100)
 parser.add_argument('--parallel_type', type=str, default='auto')
-parser.add_argument('--save_load_checkpoint', default=False, action='store_true')
 parser.add_argument('--device', type=str, default='cuda' if torch.cuda.is_available() else 'cpu')
 parser.add_argument('--use_2dh', default=False, action='store_true')
 parser.add_argument('--eval', default=False, action='store_true')
@@ -88,12 +87,6 @@ def forward(self, input):
 model = ExampleModel().to(device)
 dist_print(model)
 
-if args.save_load_checkpoint:
-    checkpoint_path = './distributed-hellworld-%d-in-%d.ckpt' % (parallel_env.global_rank, parallel_env.global_size)
-    if os.path.exists(checkpoint_path):
-        model.load_state_dict(torch.load(checkpoint_path))
-    else:
-        print('Checkpoint not loaded: file `%s` is not found' % checkpoint_path)
 
 optimizer = net.TutelDistributedOptimizer(model.parameters(), group=None, average_shared=True).warp_local(torch.optim.SGD, lr=1e-5)
 
@@ -134,6 +127,3 @@ def forward(self, input):
 
 average_time /= 10
 dist_print('\n[Summary] Average synchronized step_time = %s sec.' % average_time)
-
-if args.save_load_checkpoint:
-    torch.save(model.state_dict(), checkpoint_path)
diff --git a/tutel/experts/ffn.py b/tutel/experts/ffn.py
index d5e2907c..1fe8a04a 100644
--- a/tutel/experts/ffn.py
+++ b/tutel/experts/ffn.py
@@ -29,14 +29,14 @@ def update(self, ctx):
 
         fc1_weight = torch.empty(1, local_experts, hidden_size, model_dim)
         fc2_weight = torch.empty(1, local_experts, hidden_size, self.output_dim)
-        fc1_bias = torch.empty(1, local_experts, 1, hidden_size)
-        fc2_bias = torch.empty(1, local_experts, 1, (self.output_dim + ctx.sharded_count - 1) // ctx.sharded_count)
+        fc1_bias = torch.empty(1, local_experts, hidden_size)
+        fc2_bias = torch.empty(1, local_experts, (self.output_dim + ctx.sharded_count - 1) // ctx.sharded_count)
 
         for i in range(local_experts):
             fc1 = torch.nn.Linear(model_dim, hidden_size)
             fc2 = torch.nn.Linear(hidden_size, self.output_dim)
-            fc1_weight[0, i, :, :], fc1_bias[0, i, :, :] = fc1.weight, fc1.bias
-            fc2_weight[0, i, :, :], fc2_bias[0, i, :, :] = fc2.weight.t(), fc2.bias[:fc2_bias.size(-1)]
+            fc1_weight[0, i, :, :], fc1_bias[0, i, :] = fc1.weight, fc1.bias
+            fc2_weight[0, i, :, :], fc2_bias[0, i, :] = fc2.weight.t(), fc2.bias[:fc2_bias.size(-1)]
 
         self.register_parameter(name='batched_fc1_w', param=torch.nn.Parameter(fc1_weight.squeeze(0)))
         self.register_parameter(name='batched_fc2_w', param=torch.nn.Parameter(fc2_weight.squeeze(0)))
@@ -54,8 +54,8 @@ def forward(self, x, ctx):
 
         batched_fc1_w = self.batched_fc1_w
         batched_fc2_w = self.batched_fc2_w
-        batched_fc1_bias = self.batched_fc1_bias
-        batched_fc2_bias = self.batched_fc2_bias
+        batched_fc1_bias = self.batched_fc1_bias.unsqueeze(1)
+        batched_fc2_bias = self.batched_fc2_bias.unsqueeze(1)
 
         if ctx.ffn_zero_group is not None:
             if not ctx.use_model_parallel:
@@ -64,7 +64,7 @@ def forward(self, x, ctx):
                 batched_fc1_bias = zero_gather(batched_fc1_bias, group=ctx.ffn_zero_group).view(1, 1, -1)
 
             batched_fc2_bias = zero_gather(batched_fc2_bias, group=ctx.ffn_zero_group)
-            batched_fc2_bias = batched_fc2_bias.view(self.batched_fc2_bias.size(0), self.batched_fc2_bias.size(1), -1)
+            batched_fc2_bias = batched_fc2_bias.view(self.batched_fc2_bias.size(0), 1, -1)
             if batched_fc2_bias.size(-1) != self.output_dim:
                 batched_fc2_bias = batched_fc2_bias[:, :, :self.output_dim]
 
diff --git a/tutel/impls/communicate.py b/tutel/impls/communicate.py
index 29c3db79..667069a4 100644
--- a/tutel/impls/communicate.py
+++ b/tutel/impls/communicate.py
@@ -170,7 +170,7 @@ def simple_reduce_scatter(input, group=None, op=torch.distributed.ReduceOp.SUM):
     input = input.contiguous()
     assert input.size(0) % world_size == 0, "Cannot evenly devide dim length %s into %s slices" % (input.size(0), world_size)
     if not input.is_cuda:
-      return simple_split(simple_all_reduce(input, group, op=op))
+      return simple_split(simple_all_reduce(input, group, op=op), group=group)
     chunks = list(input.chunk(chunks=world_size, dim=0))
     output = torch.empty_like(chunks[0])
     dist.reduce_scatter(output=output, input_list=chunks, group=group, op=op)
@@ -183,7 +183,7 @@ def simple_all_gather(input, group=None):
     input = input.contiguous()
     output = torch.empty([world_size, input.numel()], device=input.device, dtype=input.dtype)
     tensor_list = list(torch.chunk(output, chunks=world_size, dim=0))
-    dist.all_gather(tensor_list=tensor_list, tensor=input, group=group)
+    dist.all_gather(tensor_list=tensor_list, tensor=input.view(1, -1), group=group)
     return output.view([-1,] + list(input.shape[1:]))
 
 class AllToAllStatus:
diff --git a/tutel/impls/moe_layer.py b/tutel/impls/moe_layer.py
index cc9f8c75..c8a31d50 100644
--- a/tutel/impls/moe_layer.py
+++ b/tutel/impls/moe_layer.py
@@ -38,6 +38,31 @@ def global_expert_count(num_local_experts, group=None):
         assert world_size % -num_local_experts == 0, "Excepting {-num_local_experts} devices to share an expert param, while global device count is {world_size}."
         return world_size // -num_local_experts
 
+    def _load_from_state_dict(self, state_dict, prefix, *args, **kwargs):
+        buff_name = prefix + '_num_global_experts'
+        if buff_name not in state_dict:
+            logging.warning(f"\033[31mYou are loading a legacy format of checkpoint with at least one Tutel MoE layer inside, which wouldn't support new Tutel feature allowing the number of experts per checkpoint file to mutate.\033[0m")
+            logging.warning(f"\033[31m  The next time you overwrite it with new checkpoint, the recording format will be updated automatically.\033[0m")
+            logging.warning(f"\033[31m  However, the new format won't be compatible with early Tutel versions, unless you force loading it with `model.load_state_dict(.., strict=False)`.\033[0m")
+            state_dict[buff_name] = self._num_global_experts
+        else:
+            state_experts, expect_experts = int(state_dict[buff_name]), self.num_global_experts
+            assert state_experts == expect_experts, "Failed to load state from checkpoint: the number of global experts mismatch (%s <- %s)" % (expect_experts, state_experts)
+
+        for name, param in self.experts.named_parameters():
+            buff_name = prefix + 'experts.' + name
+            assert buff_name in state_dict, "Could not find parameter `%s` in state_dict." % buff_name
+            if state_dict[buff_name].numel() == param.numel():
+                state_dict[buff_name] = state_dict[buff_name].view(param.shape)
+        return super()._load_from_state_dict(state_dict, prefix, *args, **kwargs)
+
+    def state_dict(self, destination=None, prefix='', keep_vars=False):
+        return super().state_dict(destination, prefix, keep_vars)
+
+    @property
+    def num_global_experts(self):
+        return int(self._num_global_experts)
+
     def __init__(
         self,
         gate_type,
@@ -71,7 +96,7 @@ def __init__(
         self.skip_moe = (int(os.environ.get('SKIP_MOE', '0')) != 0)
 
         self.num_local_experts = experts.pop('count_per_node', 1)
-        self.num_global_experts = MOELayer.global_expert_count(self.num_local_experts, self.group)
+        self.register_buffer('_num_global_experts', torch.tensor(MOELayer.global_expert_count(self.num_local_experts, self.group)))
 
         self.world_size = C.get_world_size(self.group)
         if self.num_global_experts < self.world_size:
diff --git a/tutel/moe.py b/tutel/moe.py
index 05cefa61..3b0905ce 100644
--- a/tutel/moe.py
+++ b/tutel/moe.py
@@ -2,7 +2,7 @@
 # Licensed under the MIT license.
 
 
-# Level-level Ops
+# Low-level Ops
 from .jit_kernels.gating import fast_cumsum_sub_one
 from .impls.fast_dispatch import fast_dispatcher, extract_critical, fast_encode, fast_decode
 
diff --git a/tutel/system.py b/tutel/system.py
index 324be4a6..c6276e95 100644
--- a/tutel/system.py
+++ b/tutel/system.py
@@ -87,3 +87,18 @@ def load(path, device=None):
     import torch
     npv = np.load(path)
     return torch.tensor(npv, device=device)
+
+
+def apply_rank_size_from_pattern(filename, rank, size, create_dir=True):
+    if not re.search(r'\{rank\}', filename):
+        logging.warning('Keyword `{rank}` is not found in file pattern: %s, which may cause collision in file access.' % filename)
+
+    filename = re.sub(r'\{rank\}', str(rank), re.sub(r'\{size\}', str(size), filename))
+    if create_dir:
+        filedir = os.path.dirname(filename)
+        if filedir:
+            try:
+                os.makedirs(filedir)
+            except FileExistsError:
+                pass
+    return filename