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[Benchmark] More accurate TPOT calc in benchmark_serving.py (vllm-p…
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…roject#12288)

Signed-off-by: Nick Hill <[email protected]>
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@njhill
njhill authored Jan 22, 2025
1 parent cbdc4ad commit 222a9dc
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Showing 2 changed files with 66 additions and 46 deletions.
43 changes: 27 additions & 16 deletions benchmarks/backend_request_func.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ class RequestFuncOutput:
generated_text: str = ""
success: bool = False
latency: float = 0.0
output_tokens: int = 0
ttft: float = 0.0 # Time to first token
itl: List[float] = field(
default_factory=list) # List of inter-token latencies
Expand Down Expand Up @@ -156,7 +157,7 @@ async def async_request_trt_llm(
timestamp = time.perf_counter()
# First token
if ttft == 0.0:
ttft = time.perf_counter() - st
ttft = timestamp - st
output.ttft = ttft

# Decoding phase
Expand Down Expand Up @@ -245,6 +246,9 @@ async def async_request_openai_completions(
"logprobs": request_func_input.logprobs,
"stream": True,
"ignore_eos": request_func_input.ignore_eos,
"stream_options": {
"include_usage": True,
},
}
if request_func_input.extra_body:
payload.update(request_func_input.extra_body)
Expand All @@ -256,7 +260,6 @@ async def async_request_openai_completions(
output.prompt_len = request_func_input.prompt_len

generated_text = ""
ttft = 0.0
st = time.perf_counter()
most_recent_timestamp = st
try:
Expand All @@ -271,15 +274,16 @@ async def async_request_openai_completions(

chunk = chunk_bytes.decode("utf-8").removeprefix(
"data: ")
if chunk == "[DONE]":
latency = time.perf_counter() - st
else:
if chunk != "[DONE]":
data = json.loads(chunk)

# NOTE: Some completion API might have a last
# usage summary response without a token so we
# want to check a token was generated
if data["choices"][0]["text"]:
if choices := data.get("choices"):
# Note that text could be empty here
# e.g. for special tokens
text = choices[0].get("text")
timestamp = time.perf_counter()
# First token
if not first_chunk_received:
Expand All @@ -293,7 +297,10 @@ async def async_request_openai_completions(
most_recent_timestamp)

most_recent_timestamp = timestamp
generated_text += data["choices"][0]["text"]
generated_text += text
elif usage := data.get("usage"):
output.output_tokens = usage.get(
"completion_tokens")
if first_chunk_received:
output.success = True
else:
Expand All @@ -302,7 +309,7 @@ async def async_request_openai_completions(
"Never received a valid chunk to calculate TTFT."
"This response will be marked as failed!")
output.generated_text = generated_text
output.latency = latency
output.latency = most_recent_timestamp - st
else:
output.error = response.reason or ""
output.success = False
Expand Down Expand Up @@ -342,6 +349,9 @@ async def async_request_openai_chat_completions(
"max_completion_tokens": request_func_input.output_len,
"stream": True,
"ignore_eos": request_func_input.ignore_eos,
"stream_options": {
"include_usage": True,
},
}
if request_func_input.extra_body:
payload.update(request_func_input.extra_body)
Expand All @@ -368,31 +378,32 @@ async def async_request_openai_chat_completions(

chunk = chunk_bytes.decode("utf-8").removeprefix(
"data: ")
if chunk == "[DONE]":
latency = time.perf_counter() - st
else:
if chunk != "[DONE]":
timestamp = time.perf_counter()
data = json.loads(chunk)

delta = data["choices"][0]["delta"]
if delta.get("content", None):
if choices := data.get("choices"):
content = choices[0]["delta"].get("content")
# First token
if ttft == 0.0:
ttft = time.perf_counter() - st
ttft = timestamp - st
output.ttft = ttft

# Decoding phase
else:
output.itl.append(timestamp -
most_recent_timestamp)

generated_text += delta["content"]
generated_text += content
elif usage := data.get("usage"):
output.output_tokens = usage.get(
"completion_tokens")

most_recent_timestamp = timestamp

output.generated_text = generated_text
output.success = True
output.latency = latency
output.latency = most_recent_timestamp - st
else:
output.error = response.reason or ""
output.success = False
Expand Down
69 changes: 39 additions & 30 deletions benchmarks/benchmark_serving.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
import argparse
import asyncio
import base64
import gc
import io
import json
import os
Expand Down Expand Up @@ -423,7 +424,7 @@ def calculate_metrics(
tokenizer: PreTrainedTokenizerBase,
selected_percentile_metrics: List[str],
selected_percentiles: List[float],
gootput_config_dict: Dict[str, float],
goodput_config_dict: Dict[str, float],
) -> Tuple[BenchmarkMetrics, List[int]]:
actual_output_lens: List[int] = []
total_input = 0
Expand All @@ -436,19 +437,23 @@ def calculate_metrics(
e2els: List[float] = []
for i in range(len(outputs)):
if outputs[i].success:
# We use the tokenizer to count the number of output tokens for all
# serving backends instead of looking at len(outputs[i].itl) since
# multiple output tokens may be bundled together
# Note : this may inflate the output token count slightly
output_len = len(
tokenizer(outputs[i].generated_text,
add_special_tokens=False).input_ids)
output_len = outputs[i].output_tokens

if output_len is None:
# We use the tokenizer to count the number of output tokens
# for some serving backends instead of looking at
# len(outputs[i].itl) since multiple output tokens may be
# bundled together
# Note : this may inflate the output token count slightly
output_len = len(
tokenizer(outputs[i].generated_text,
add_special_tokens=False).input_ids)
actual_output_lens.append(output_len)
total_input += input_requests[i][1]
tpot = 0
if output_len > 1:
tpot = (outputs[i].latency - outputs[i].ttft) / (output_len -
1)
latency_minus_ttft = outputs[i].latency - outputs[i].ttft
tpot = latency_minus_ttft / (output_len - 1)
tpots.append(tpot)
# Note: if output_len <= 1, we regard tpot as 0 for goodput
all_tpots.append(tpot)
Expand All @@ -459,21 +464,21 @@ def calculate_metrics(
else:
actual_output_lens.append(0)

if gootput_config_dict:
if goodput_config_dict:
valid_metrics = []
slo_values = []

if "ttft" in gootput_config_dict:
if "ttft" in goodput_config_dict:
valid_metrics.append(ttfts)
slo_values.append(gootput_config_dict["ttft"] /
slo_values.append(goodput_config_dict["ttft"] /
MILLISECONDS_TO_SECONDS_CONVERSION)
if "tpot" in gootput_config_dict:
if "tpot" in goodput_config_dict:
valid_metrics.append(all_tpots)
slo_values.append(gootput_config_dict["tpot"] /
slo_values.append(goodput_config_dict["tpot"] /
MILLISECONDS_TO_SECONDS_CONVERSION)
if "e2el" in gootput_config_dict:
if "e2el" in goodput_config_dict:
valid_metrics.append(e2els)
slo_values.append(gootput_config_dict["e2el"] /
slo_values.append(goodput_config_dict["e2el"] /
MILLISECONDS_TO_SECONDS_CONVERSION)

for req_metric in zip(*valid_metrics):
Expand Down Expand Up @@ -537,7 +542,7 @@ async def benchmark(
selected_percentile_metrics: List[str],
selected_percentiles: List[str],
ignore_eos: bool,
gootput_config_dict: Dict[str, float],
goodput_config_dict: Dict[str, float],
max_concurrency: Optional[int],
):
if backend in ASYNC_REQUEST_FUNCS:
Expand Down Expand Up @@ -661,7 +666,7 @@ async def limited_request_func(request_func_input, pbar):
tokenizer=tokenizer,
selected_percentile_metrics=selected_percentile_metrics,
selected_percentiles=selected_percentiles,
gootput_config_dict=gootput_config_dict,
goodput_config_dict=goodput_config_dict,
)

print("{s:{c}^{n}}".format(s=' Serving Benchmark Result ', n=50, c='='))
Expand All @@ -673,7 +678,7 @@ async def limited_request_func(request_func_input, pbar):
metrics.total_output))
print("{:<40} {:<10.2f}".format("Request throughput (req/s):",
metrics.request_throughput))
if gootput_config_dict:
if goodput_config_dict:
print("{:<40} {:<10.2f}".format("Request goodput (req/s):",
metrics.request_goodput))
print("{:<40} {:<10.2f}".format("Output token throughput (tok/s):",
Expand All @@ -688,7 +693,7 @@ async def limited_request_func(request_func_input, pbar):
"total_output_tokens": metrics.total_output,
"request_throughput": metrics.request_throughput,
"request_goodput:":
metrics.request_goodput if gootput_config_dict else None,
metrics.request_goodput if goodput_config_dict else None,
"output_throughput": metrics.output_throughput,
"total_token_throughput": metrics.total_token_throughput,
"input_lens": [output.prompt_len for output in outputs],
Expand Down Expand Up @@ -744,11 +749,11 @@ def process_one_metric(

def check_goodput_args(args):
# Check and parse goodput arguments
gootput_config_dict = {}
goodput_config_dict = {}
VALID_NAMES = ["ttft", "tpot", "e2el"]
if args.goodput:
gootput_config_dict = parse_goodput(args.goodput)
for slo_name, slo_val in gootput_config_dict.items():
goodput_config_dict = parse_goodput(args.goodput)
for slo_name, slo_val in goodput_config_dict.items():
if slo_name not in VALID_NAMES:
raise ValueError(
f"Invalid metric name found, {slo_name}: {slo_val}. "
Expand All @@ -759,22 +764,22 @@ def check_goodput_args(args):
f"Invalid value found, {slo_name}: {slo_val}. "
"The service level objective value should be "
"non-negative.")
return gootput_config_dict
return goodput_config_dict


def parse_goodput(slo_pairs):
gootput_config_dict = {}
goodput_config_dict = {}
try:
for slo_pair in slo_pairs:
slo_name, slo_val = slo_pair.split(":")
gootput_config_dict[slo_name] = float(slo_val)
goodput_config_dict[slo_name] = float(slo_val)
except ValueError as err:
raise argparse.ArgumentTypeError(
"Invalid format found for service level objectives. "
"Specify service level objectives for goodput as \"KEY:VALUE\" "
"pairs, where the key is a metric name, and the value is a "
"number in milliseconds.") from err
return gootput_config_dict
return goodput_config_dict


def main(args: argparse.Namespace):
Expand Down Expand Up @@ -874,7 +879,11 @@ def main(args: argparse.Namespace):
else:
raise ValueError(f"Unknown dataset: {args.dataset_name}")

gootput_config_dict = check_goodput_args(args)
goodput_config_dict = check_goodput_args(args)

# Avoid GC processing "static" data - reduce pause times.
gc.collect()
gc.freeze()

benchmark_result = asyncio.run(
benchmark(
Expand All @@ -896,7 +905,7 @@ def main(args: argparse.Namespace):
float(p) for p in args.metric_percentiles.split(",")
],
ignore_eos=args.ignore_eos,
gootput_config_dict=gootput_config_dict,
goodput_config_dict=goodput_config_dict,
max_concurrency=args.max_concurrency,
))

Expand Down

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