[Feature] Split cross-entropy computation in SP (#5959)

* halfway

* fix cross-PP-stage position id length diff bug

* fix typo

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* unified cross entropy func for all shardformer models

* remove redundant lines

* add basic ring attn; debug cross entropy

* fwd bwd logic complete

* fwd bwd logic complete; add experimental triton rescale

* precision tests passed

* precision tests passed

* fix typos and remove misc files

* update softmax_lse shape by new interface

* change tester name

* remove buffer clone; support packed seq layout

* add varlen tests

* fix typo

* all tests passed

* add dkv_group; fix mask

* remove debug statements

* adapt chatglm, command-R, qwen

* debug

* halfway

* fix cross-PP-stage position id length diff bug

* fix typo

* fix typo

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* unified cross entropy func for all shardformer models

* remove redundant lines

* add basic ring attn; debug cross entropy

* fwd bwd logic complete

* fwd bwd logic complete; add experimental triton rescale

* precision tests passed

* precision tests passed

* fix typos and remove misc files

* add sp_mode to benchmark; fix varlen interface

* update softmax_lse shape by new interface

* add varlen tests

* fix typo

* all tests passed

* add dkv_group; fix mask

* remove debug statements

* add comments

* q1 index only once

* remove events to simplify stream sync

* simplify forward/backward logic

* 2d ring forward passed

* 2d ring backward passed

* fixes

* fix ring attn loss

* 2D ring backward + llama passed

* merge

* update logger

* fix typo

* rebase

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* fix typo

* remove typos

* fixes

* support GPT

---------

Co-authored-by: Edenzzzz <wtan45@wisc.edu>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

colossalai/shardformer/layer/loss.py

@@ -153,7 +153,6 @@ def dist_cross_entropy(
     labels: torch.Tensor,  # [B, S] or [B, S, Vocab_size]
     logits: torch.Tensor,  # [B, S, Vocab_size]
     shard_config: ShardConfig,
-    out_features: int,
     vocab_size: int,
     dtype: torch.dtype,
     seq_dim: int = 1,
@@ -226,13 +225,13 @@ def dist_cross_entropy(
             logits,
             labels,
             process_group=shard_config.tensor_parallel_process_group,
-            vocab_size=out_features,
+            vocab_size=vocab_size,
             dtype=dtype,
             mode="sum",
         )
     else:
         # NOTE if use TP and not parallel_output, the output is gathered in VocabParallelLMHead1D
-        logits = logits.view(-1, vocab_size)
+        logits = logits.view(-1, logits.size(-1))
         loss = loss_fct(logits, labels)
 
     # Reduce loss instead of gathering logits over seq dim for savings