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fix: use proper iterations times and fix round sizes #67

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Merged
art049 merged 3 commits into from
Jan 31, 2025
Merged

fix: use proper iterations times and fix round sizes #67

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cc10330
fix: use time per iteration instead of total round time in stats
art049 Jan 28, 2025
6e1d63e
feat: increase the min round time to a bigger value (+/- 1ms)
art049 Jan 28, 2025
4333c1f
refactor: replace hardcoded outlier factor for improved readability
art049 Jan 28, 2025
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34 changes: 21 additions & 13 deletions src/pytest_codspeed/instruments/walltime.py
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,10 @@
DEFAULT_WARMUP_TIME_NS = 1_000_000_000
DEFAULT_MAX_TIME_NS = 3_000_000_000
TIMER_RESOLUTION_NS = get_clock_info("perf_counter").resolution * 1e9
DEFAULT_MIN_ROUND_TIME_NS = TIMER_RESOLUTION_NS * 100
DEFAULT_MIN_ROUND_TIME_NS = TIMER_RESOLUTION_NS * 1_000_000

IQR_OUTLIER_FACTOR = 1.5
STDEV_OUTLIER_FACTOR = 3


@dataclass
Expand Down Expand Up @@ -69,13 +72,14 @@ class BenchmarkStats:
@classmethod
def from_list(
cls,
times_ns: list[float],
times_per_round_ns: list[float],
*,
rounds: int,
iter_per_round: int,
warmup_iters: int,
total_time: float,
) -> BenchmarkStats:
times_ns = [t / iter_per_round for t in times_per_round_ns]
stdev_ns = stdev(times_ns) if len(times_ns) > 1 else 0
mean_ns = mean(times_ns)
if len(times_ns) > 1:
Expand All @@ -88,12 +92,16 @@ def from_list(
)
iqr_ns = q3_ns - q1_ns
iqr_outlier_rounds = sum(
1 for t in times_ns if t < q1_ns - 1.5 * iqr_ns or t > q3_ns + 1.5 * iqr_ns
1
for t in times_ns
if t < q1_ns - IQR_OUTLIER_FACTOR * iqr_ns
or t > q3_ns + IQR_OUTLIER_FACTOR * iqr_ns
)
stdev_outlier_rounds = sum(
1
for t in times_ns
if t < mean_ns - 3 * stdev_ns or t > mean_ns + 3 * stdev_ns
if t < mean_ns - STDEV_OUTLIER_FACTOR * stdev_ns
or t > mean_ns + STDEV_OUTLIER_FACTOR * stdev_ns
)

return cls(
Expand Down Expand Up @@ -129,20 +137,20 @@ def run_benchmark(
out = fn(*args, **kwargs)

# Warmup
times_ns: list[float] = []
times_per_round_ns: list[float] = []
warmup_start = start = perf_counter_ns()
while True:
start = perf_counter_ns()
fn(*args, **kwargs)
end = perf_counter_ns()
times_ns.append(end - start)
times_per_round_ns.append(end - start)
if end - warmup_start > config.warmup_time_ns:
break

# Round sizing
warmup_mean_ns = mean(times_ns)
warmup_iters = len(times_ns)
times_ns.clear()
warmup_mean_ns = mean(times_per_round_ns)
warmup_iters = len(times_per_round_ns)
times_per_round_ns.clear()
iter_per_round = (
int(ceil(config.min_round_time_ns / warmup_mean_ns))
if warmup_mean_ns <= config.min_round_time_ns
Expand All @@ -163,7 +171,7 @@ def run_benchmark(
for _ in iter_range:
fn(*args, **kwargs)
end = perf_counter_ns()
times_ns.append(end - start)
times_per_round_ns.append(end - start)

if end - run_start > config.max_time_ns:
# TODO: log something
Expand All @@ -172,7 +180,7 @@ def run_benchmark(
total_time = (benchmark_end - run_start) / 1e9

stats = BenchmarkStats.from_list(
times_ns,
times_per_round_ns,
rounds=rounds,
total_time=total_time,
iter_per_round=iter_per_round,
Expand Down Expand Up @@ -240,12 +248,12 @@ def _print_benchmark_table(self) -> None:

for bench in self.benchmarks:
rsd = bench.stats.stdev_ns / bench.stats.mean_ns
rsd_text = Text(f"{rsd*100:.1f}%")
rsd_text = Text(f"{rsd * 100:.1f}%")
if rsd > 0.1:
rsd_text.stylize("red bold")
table.add_row(
escape(bench.name),
f"{bench.stats.min_ns/bench.stats.iter_per_round:,.0f}ns",
f"{bench.stats.min_ns / bench.stats.iter_per_round:,.0f}ns",
rsd_text,
f"{bench.stats.total_time:,.2f}s",
f"{bench.stats.iter_per_round * bench.stats.rounds:,}",
Expand Down