[core ] Integrate Flash attention 2 in most used models (#25598)

* v1

* oops

* working v1

* fixup

* add some TODOs

* fixup

* padding support + try with module replacement

* nit

* alternative design

* oops

* add `use_cache` support for llama

* v1 falcon

* nit

* a bit of refactor

* nit

* nits nits

* add v1 padding support falcon (even though it seemed to work before)

* nit

* falcon works

* fixup

* v1 tests

* nit

* fix generation llama flash

* update tests

* fix tests + nits

* fix copies

* fix nit

* test- padding mask

* stype

* add more mem efficient support

* Update src/transformers/modeling_utils.py

Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

* fixup

* nit

* fixup

* remove it from config when saving

* fixup

* revert docstring

* add more checks

* use values

* oops

* new version

* fixup

* add same trick for falcon

* nit

* add another test

* change tests

* fix issues with GC and also falcon

* fixup

* oops

* Update src/transformers/models/falcon/modeling_falcon.py

Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>

* add init_rope

* updates

* fix copies

* fixup

* fixup

* more clarification

* fixup

* right padding tests

* add docs

* add FA in docker image

* more clarifications

* add some figures

* add todo

* rectify comment

* Change to FA2

* Update docs/source/en/perf_infer_gpu_one.md

Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>

* split in two lines

* change test name

* add more tests

* some clean up

* remove `rearrange` deps

* add more docs

* revert changes on dockerfile

* Revert "revert changes on dockerfile"

This reverts commit 8d72a66b4b9b771abc3f15a9b9506b4246d62d8e.

* revert changes on dockerfile

* Apply suggestions from code review

Co-authored-by: Lysandre Debut <hi@lysand.re>

* address some comments

* docs

* use inheritance

* Update src/transformers/testing_utils.py

Co-authored-by: Lysandre Debut <hi@lysand.re>

* fixup

* Apply suggestions from code review

Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>

* Update src/transformers/modeling_utils.py

* final comments

* clean up

* style

* add cast + warning for PEFT models

* fixup

---------

Co-authored-by: Felix Marty <9808326+fxmarty@users.noreply.github.com>
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>
Co-authored-by: Lysandre Debut <hi@lysand.re>

src/transformers/testing_utils.py

@@ -60,6 +60,7 @@ from .utils import (
     is_detectron2_available,
     is_essentia_available,
     is_faiss_available,
+    is_flash_attn_available,
     is_flax_available,
     is_fsdp_available,
     is_ftfy_available,
@@ -392,6 +393,16 @@ def require_torch(test_case):
     return unittest.skipUnless(is_torch_available(), "test requires PyTorch")(test_case)
 
 
+def require_flash_attn(test_case):
+    """
+    Decorator marking a test that requires Flash Attention.
+
+    These tests are skipped when Flash Attention isn't installed.
+
+    """
+    return unittest.skipUnless(is_flash_attn_available(), "test requires Flash Attention")(test_case)
+
+
 def require_peft(test_case):
     """
     Decorator marking a test that requires PEFT.