Attention mask and position id fixes for packing (#285)

* fix attetion mask with packing

* set position ids and use block diagonal attn mask

* fix expand mask for multiple batch items, make sure we pad position_ids

* don't move masks to cpu

* use multi pack dataloader w random sampler

* add position_ids back

* more fixes for dataloader integration

* est total tokens, fix field loop

* more fixes, position_ids seems broken

* more fixes for sample packing

* use distributed sampler, avoid accelerate prepare

* use accelerator prepare for dataloader

* fix for position_ids w packing

* Update src/axolotl/utils/dataloader.py

* validation for sample packing and doc

* more fixes for 4k and optimizations

* optimized expand mask fn

* better handling of variance in multipack dataloader length and trainer hanging when it runs out of data

* fix rounding of len of batches to int

* better handling so that all devices have the same dataloader len

* fix step calc for packing

* pass sample packing efficiency to training args

* add a test for the mask expansion for sequence packing

* only process eval dataset for packing if not None

* don't split batches when packing

* weighted CE losses

* weighted CEL fixes

* limit packing to sequences of max seq len

* seq_len_multiple for packing

* make sure the chunk size is an int

* sample_packing_seq_len_multiplier config

* use cumulative seq len with var len flash attn v2 w packing

* properly calculate max len

* fix flash-attn, xformers, packing, support chatml

* fix chatml system prompt for openorca, legacy tokenizer opts

* add chatml

* add unit tests for cum seq lens, add ability to build cu_seq_lens from positional ids, fix prompt test

* fix test and pylint checks

* more packing and dataset optimizations and fixes

* filter w multiple cpus

* more fixes and optimizations

* fixes and go back to distributed sampler since batch sampler won't work

* fix counts by accounting for num devices

* fix steps calculation

* previous accelerate is still most performant

* add numba to requirements.

* use custom distributed checks

* fix sampler to prevent overfit w new epochs

* let's not cleanup the cached datasets

* calculate cum seq lens with pos_ids instead of mask, simplify packing params, fix distributed barrier

* speed optimizations and set accelerate fsdp env vars

* optimize dataset concatenation?

* more optimizations for dataset handling

* fix import for annotation

* manual pre-commit fixes

* another sum optimization and bug fix for calc steps

* fix packing estimations

* fix formatting

* pylint problems

* add back flash attention branch for handling unpacked sequences seperately

* Address PR feedback

* add optional sample packing config params to readme

src/axolotl/prompters.py

@@ -16,6 +16,7 @@ class PromptStyle(Enum):
 
     INSTRUCT = "instruct"
     CHAT = "chat"
+    CHATML = "chatml"
 
 
 class AlpacaPrompter:
@@ -25,6 +26,7 @@ class AlpacaPrompter:
 
     system_prompt = "Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.\n\n"
     system_no_input_prompt = "Below is an instruction that describes a task. Write a response that appropriately completes the request.\n\n"
+    system_format: str
     turn_format: str
     turn_no_input_format: str
     prompt_style: Optional[PromptStyle] = None
@@ -34,14 +36,23 @@ class AlpacaPrompter:
         self.match_prompt_style()
 
     def match_prompt_style(self):
+        # pylint: disable=duplicate-code
         if self.prompt_style == PromptStyle.INSTRUCT.value:
             self.turn_format = "### Instruction:\n{instruction}\n\n### Input:\n{input}\n\n### Response:\n"
             self.turn_no_input_format = (
                 "### Instruction:\n{instruction}\n\n### Response:\n"
             )
+            self.system_format = "### System:\n{system}\n\n"
         if self.prompt_style == PromptStyle.CHAT.value:
             self.turn_format = "USER: {instruction}\n{input}\nASSISTANT:"
             self.turn_no_input_format = "USER: {instruction}\nASSISTANT:"
+            self.system_format = "SYSTEM: {system}\n"
+        if self.prompt_style == PromptStyle.CHATML.value:
+            self.turn_format = "<|im_start|>user\n{instruction}\n{input}<|im_end|>\n<|im_start|>assistant\n"
+            self.turn_no_input_format = (
+                "<|im_start|>user\n{instruction}<|im_end|>\n<|im_start|>assistant\n"
+            )
+            self.system_format = "<|im_start|>system\n{system}<|im_end|>\n"
 
     def build_prompt(
         self,