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exllamav2/examples/cfg.py
2024-01-01 23:48:24 +01:00

97 lines
2.8 KiB
Python

import sys, os
sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
from exllamav2 import *
from exllamav2.generator import *
# Initialize model and cache
model_directory = "/mnt/str/models/llama2-70b-chat-exl2/4.0bpw"
config = ExLlamaV2Config()
config.model_dir = model_directory
config.max_batch_size = 2
config.no_flash_attn = True
config.prepare()
model = ExLlamaV2(config)
print("Loading model: " + model_directory)
cache = ExLlamaV2Cache(model, lazy = True, batch_size = 2)
model.load_autosplit(cache)
tokenizer = ExLlamaV2Tokenizer(config)
# Initialize generator
generator = ExLlamaV2StreamingGenerator(model, cache, tokenizer)
# Settings
settings = ExLlamaV2Sampler.Settings()
settings.temperature = 0.85
settings.top_k = 50
settings.top_p = 0.8
settings.top_a = 0.0
settings.token_repetition_penalty = 1.05
max_new_tokens = 250
# Prompt
positive = \
"""[INST] <<SYS>>
You are a cheerful, bubbly and respectful assistant.
<</SYS>>
{prompt} [/INST]"""
negative = \
"""[INST] <<SYS>>
You are a rude and obnoxious assistant.
<</SYS>>
{prompt} [/INST]"""
q = """Tell me about Homer Simpson."""
prompt_a = positive.replace("{prompt}", q)
prompt_b = negative.replace("{prompt}", q)
print("-------------------------------------------")
print("Prompt a:\n" + prompt_a + "\n")
print("-------------------------------------------")
print("Prompt b:\n" + prompt_b + "\n")
for x in range(11):
# cfg_scale is the weight of the first prompt in the batch, while the second prompt is weighted as (1 - cfg_scale).
#
# - at cfg_scale == 0, only the second prompt is effective
# - at 0 < cfg_scale < 1, the sampled logits will be a weighted average of the normalized outputs of both prompts
# - at cfg_scale == 1, only the first prompt is effective
# - at cfg_scale > 1, the second prompt will have a negative weight, emphasizing the difference between the two
settings.cfg_scale = x / 5
# Start a batched generation. CFG requires a batch size of exactly 2. Offsets and padding mask are required
input_ids, offsets = tokenizer.encode([prompt_a, prompt_b], encode_special_tokens = True, return_offsets = True)
mask = tokenizer.padding_mask(input_ids)
generator.begin_stream(input_ids, settings, input_mask = mask, position_offsets = offsets)
generator.set_stop_conditions([tokenizer.eos_token_id])
print(f"---------------------------------------------------------------------------------------")
print(f"cfg_scale = {settings.cfg_scale:.1f}")
print()
generated_tokens = 0
max_new_tokens = 200
while True:
chunk, eos, _ = generator.stream()
generated_tokens += 1
print (chunk, end = "")
sys.stdout.flush()
if eos or generated_tokens == max_new_tokens: break
print()