Failed attempt at evaluating exllama_hf perplexity

modules/evaluate.py

@@ -100,7 +100,7 @@ def calculate_perplexity(models, input_dataset, stride, _max_length):
             target_ids[:, :-trg_len] = -100
 
             with torch.no_grad():
-                outputs = shared.model(input_ids, labels=target_ids)
+                outputs = shared.model(input_ids=input_ids, labels=target_ids)
 
                 # loss is calculated using CrossEntropyLoss which averages over valid labels
                 # N.B. the model only calculates loss over trg_len - 1 labels, because it internally shifts the labels

modules/exllama_hf.py

@@ -1,15 +1,10 @@
 import os
-import sys
 from pathlib import Path
-from typing import *
+from typing import Any, Dict, Optional, Union
 
 import torch
-from transformers import (
-    GenerationConfig,
-    LlamaTokenizer,
-    PretrainedConfig,
-    PreTrainedModel
-)
+from torch.nn import CrossEntropyLoss
+from transformers import GenerationConfig, PretrainedConfig, PreTrainedModel
 from transformers.modeling_outputs import CausalLMOutputWithPast
 
 from modules import shared
@@ -43,13 +38,29 @@ class ExllamaHF(PreTrainedModel):
     def __call__(self, *args, **kwargs):
         # TODO: Some decoding methods (such as Contrastive Search) may not work at this time
         assert len(args) == 0, 'no *args should be passed to forward'
-        use_cache = kwargs['use_cache']
+        use_cache = kwargs.get('use_cache', True)
+        labels = kwargs.get('labels', None)
         seq = kwargs['input_ids'][0].tolist()
         cache = kwargs['past_key_values'] if 'past_key_values' in kwargs else None
         if cache is None:
             cache = ExLlamaCache(self.ex_model)
             self.ex_model.forward(torch.tensor([seq[:-1]], dtype=torch.long), cache, preprocess_only=True)
+
         logits = self.ex_model.forward(torch.tensor([seq[-1:]], dtype=torch.long), cache).to(kwargs['input_ids'].device)
+
+        loss = None
+        if labels is not None:
+            # Shift so that tokens < n predict n
+            shift_logits = logits[..., :-1, :].contiguous()
+            shift_labels = labels[..., 1:].contiguous()
+            # Flatten the tokens
+            loss_fct = CrossEntropyLoss()
+            shift_logits = shift_logits.view(-1, logits.shape[-1])
+            shift_labels = shift_labels.view(-1)
+            # Enable model parallelism
+            shift_labels = shift_labels.to(shift_logits.device)
+            loss = loss_fct(shift_logits, shift_labels)
+
         return CausalLMOutputWithPast(logits=logits, past_key_values=cache if use_cache else None)
 
     @classmethod