Implement logprobs parameter for text completion. Closes #2
This commit is contained in:
Andrei Betlen
parent
2a60eb820f
commit
b3805bb9cc
2 changed files with 111 additions and 16 deletions
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@ -2,6 +2,7 @@ import os
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import sys
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import uuid
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import time
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import math
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import multiprocessing
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from typing import List, Optional, Union, Generator, Sequence, Iterator
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from collections import deque
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@ -76,6 +77,9 @@ class Llama:
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)
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self.tokens_consumed = 0
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self.n_batch = min(n_ctx, n_batch)
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self.n_tokens = 0
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self.n_past = 0
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self.all_logits: List[List[float]] = [] # TODO: Use an array instead of a list.
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self.n_threads = n_threads or max(multiprocessing.cpu_count() // 2, 1)
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@ -136,6 +140,9 @@ class Llama:
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[llama_cpp.llama_token(0)] * self.last_n_tokens_size
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)
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self.tokens_consumed = 0
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self.n_tokens = 0
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self.n_past = 0
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self.all_logits = []
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def eval(self, tokens: Sequence[llama_cpp.llama_token]):
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"""Evaluate a list of tokens.
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@ -147,18 +154,31 @@ class Llama:
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n_ctx = int(llama_cpp.llama_n_ctx(self.ctx))
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for i in range(0, len(tokens), self.n_batch):
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batch = tokens[i : min(len(tokens), i + self.n_batch)]
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n_past = min(n_ctx - len(batch), self.tokens_consumed)
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self.n_past = min(n_ctx - len(batch), self.tokens_consumed)
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self.n_tokens = len(batch)
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return_code = llama_cpp.llama_eval(
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ctx=self.ctx,
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tokens=(llama_cpp.llama_token * len(batch))(*batch),
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n_tokens=llama_cpp.c_int(len(batch)),
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n_past=llama_cpp.c_int(n_past),
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n_tokens=llama_cpp.c_int(self.n_tokens),
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n_past=llama_cpp.c_int(self.n_past),
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n_threads=llama_cpp.c_int(self.n_threads),
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)
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if int(return_code) != 0:
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raise RuntimeError(f"llama_eval returned {return_code}")
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self.last_n_tokens_data.extend(batch)
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self.tokens_consumed += len(batch)
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if self.params.logits_all:
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self.all_logits.extend(self._logits())
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def _logits(self) -> List[List[float]]:
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"""Return the logits from the last call to llama_eval."""
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assert self.ctx is not None
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n_vocab = llama_cpp.llama_n_vocab(self.ctx)
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cols = int(n_vocab)
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rows = self.n_tokens if self.params.logits_all else 1
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logits_view = llama_cpp.llama_get_logits(self.ctx)
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logits = [[logits_view[i * cols + j] for j in range(cols)] for i in range(rows)]
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return logits
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def sample(
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self,
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@ -327,14 +347,55 @@ class Llama:
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else:
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stop_sequences = []
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finish_reason = None
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for token in self.generate(
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prompt_tokens,
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top_k=top_k,
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top_p=top_p,
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temp=temperature,
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repeat_penalty=repeat_penalty,
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):
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text_offset = 0
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text_offsets: List[int] = []
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token_logprobs: List[float] = []
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tokens: List[str] = []
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top_logprobs: List[Dict[str, float]] = []
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self.reset()
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self.eval(prompt_tokens)
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if logprobs is not None and self.params.logits_all is False:
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raise ValueError(
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"logprobs is not supported for models created with logits_all=False"
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)
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if logprobs is not None:
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token_strs = [
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self.detokenize([token]).decode("utf-8") for token in prompt_tokens
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]
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logprobs_all = [
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[Llama.logit_to_logprob(logit) for logit in row]
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for row in self.all_logits
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]
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for token, token_str, logprobs_token in zip(
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prompt_tokens, token_strs, logprobs_all
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):
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text_offsets.append(text_offset)
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text_offset += len(token_str)
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tokens.append(token_str)
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sorted_logprobs = list(
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sorted(
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zip(logprobs_token, range(len(logprobs_token))), reverse=True
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)
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)
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token_logprobs.append(sorted_logprobs[int(token)][0])
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top_logprob = {
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self.detokenize([llama_cpp.llama_token(i)]).decode("utf-8"): logprob
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for logprob, i in sorted_logprobs[:logprobs]
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}
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top_logprob.update({token_str: sorted_logprobs[int(token)][0]})
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top_logprobs.append(top_logprob)
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finish_reason = "length"
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while True:
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token = self.sample(
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top_k=top_k,
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top_p=top_p,
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temp=temperature,
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repeat_penalty=repeat_penalty,
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)
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if token == llama_cpp.llama_token_eos():
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text = self.detokenize(completion_tokens)
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finish_reason = "stop"
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@ -377,13 +438,35 @@ class Llama:
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}
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],
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}
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if logprobs is not None:
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# TODO: Confirm wether this should happen before or after
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# next eval.
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token_str = self.detokenize([token]).decode("utf-8")
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text_offsets.append(text_offset)
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text_offset += len(token_str)
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tokens.append(token_str)
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logprobs_token = [
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Llama.logit_to_logprob(logit) for logit in self.all_logits[-1]
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]
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sorted_logprobs = list(
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sorted(
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zip(logprobs_token, range(len(logprobs_token))), reverse=True
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)
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)
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token_logprobs.append(sorted_logprobs[int(token)][0])
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top_logprob = {
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self.detokenize([llama_cpp.llama_token(i)]).decode("utf-8"): logprob
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for logprob, i in sorted_logprobs[:logprobs]
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}
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top_logprob.update({token_str: logprobs_token[int(token)]})
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top_logprobs.append(top_logprob)
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if len(completion_tokens) >= max_tokens:
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text = self.detokenize(completion_tokens)
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finish_reason = "length"
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break
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if finish_reason is None:
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finish_reason = "length"
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self.eval([token])
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if stream:
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yield {
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@ -410,8 +493,14 @@ class Llama:
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if suffix is not None:
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text = text + suffix
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logprobs_or_none: Optional[CompletionLogprobs] = None
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if logprobs is not None:
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raise NotImplementedError("logprobs not implemented")
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logprobs_or_none = {
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"tokens": tokens,
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"text_offset": text_offsets,
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"token_logprobs": token_logprobs,
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"top_logprobs": top_logprobs,
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}
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if self.verbose:
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llama_cpp.llama_print_timings(self.ctx)
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@ -425,7 +514,7 @@ class Llama:
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{
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"text": text,
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"index": 0,
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"logprobs": None,
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"logprobs": logprobs_or_none,
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"finish_reason": finish_reason,
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}
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],
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@ -704,3 +793,7 @@ class Llama:
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def token_bos() -> llama_cpp.llama_token:
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"""Return the beginning-of-sequence token."""
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return llama_cpp.llama_token_bos()
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@staticmethod
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def logit_to_logprob(x: float) -> float:
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return math.log(1.0 + math.exp(x))
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@ -33,6 +33,7 @@ class Settings(BaseSettings):
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use_mlock: bool = False # This causes a silent failure on platforms that don't support mlock (e.g. Windows) took forever to figure out...
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embedding: bool = True
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last_n_tokens_size: int = 64
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logits_all: bool = False
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app = FastAPI(
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@ -52,6 +53,7 @@ llama = llama_cpp.Llama(
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f16_kv=settings.f16_kv,
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use_mlock=settings.use_mlock,
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embedding=settings.embedding,
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logits_all=settings.logits_all,
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n_threads=settings.n_threads,
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n_batch=settings.n_batch,
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n_ctx=settings.n_ctx,
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