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Prompt cache length default #61

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Prompt cache length default #61

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8ac7890
Fix prompt cache length default to auto-compute from prompt_cache_max…
cursoragent Feb 22, 2026
27b5a10
Keep --prompt-cache-max-len default as 0
cursoragent Feb 22, 2026
9460832
Revert to None default for --prompt-cache-max-len
cursoragent Feb 22, 2026
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16 changes: 13 additions & 3 deletions llm_bench/load_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -162,13 +162,20 @@ def _create_dataset(cls, options: argparse.Namespace):
prompt = options.prompt
dataset_file = "code.txt"

if options.prompt_cache_max_len is not None:
common_tokens = options.prompt_cache_max_len
elif options.prompt_cache_max_pct is not None:
common_tokens = int(options.prompt_tokens * options.prompt_cache_max_pct / 100)
else:
common_tokens = 0

return TranslationDataset(
path=os.path.join(os.path.dirname(os.path.abspath(__file__)), dataset_file),
prompt="\n\n" + prompt,
tokenizer_path=options.tokenizer,
chat=options.chat,
num_tokens=options.prompt_tokens,
common_tokens=options.prompt_cache_max_len,
common_tokens=common_tokens,
)
else:
raise ValueError(f"Unknown dataset: {options.dataset}")
Expand Down Expand Up @@ -1451,8 +1458,11 @@ def init_parser(parser):
"--prompt-cache-max-len",
env_var="PROMPT_CACHE_MAX_LEN",
type=int,
default=0,
help="Maximum length of the prompt cache to use. Defaults to 0 (no caching).",
default=None,
help="Maximum number of shared prefix tokens across requests. "
"If not specified but --prompt-cache-max-pct is set, auto-computed as "
"int(prompt_tokens * prompt_cache_max_pct / 100). Defaults to 0 (no shared prefix) "
"when neither this nor --prompt-cache-max-pct is provided.",
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@cursor cursor bot Feb 22, 2026 •
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Done. The default for --prompt-cache-max-len is back to 0. The auto-computation logic now works as:

  • If --prompt-cache-max-len is explicitly set to a non-zero value, use it directly.
  • Otherwise, if --prompt-cache-max-pct is provided, auto-compute common_tokens = int(prompt_tokens * prompt_cache_max_pct / 100).
  • If neither is meaningfully set, common_tokens stays 0.

So --prompt-cache-max-pct 100 --prompt-tokens 8192 works on its own, producing common_tokens = 8192.

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)
parser.add_argument(
"--prompt-cache-max-pct",
Expand Down