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fix: Compute real standard deviation in output instead of mean(). #21

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Merged
Hugoch merged 2 commits into from
Jan 14, 2026
Merged

fix: Compute real standard deviation in output instead of mean(). #21

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862eb15
fix: Compute real standard deviation in output instead of mean().
Hugoch Jan 14, 2026
5c0f1d2
fix: Correct standard deviation calculation by using n_iters - 1 (Bes…
Hugoch Jan 14, 2026
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35 changes: 29 additions & 6 deletions src/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,8 @@ struct BurnResult {
flops_max: usize,
flops_min: usize,
flops_sum: usize,
flops_mean: f64,
flops_m2: f64, // For Welford's algorithm: sum of squared differences from mean
n_iters: usize,
temp_max: usize,
temp_sum: usize,
Expand Down Expand Up @@ -114,6 +116,28 @@ impl BurnResult {
}
}

fn flops_stddev(&self) -> f64 {
if self.n_iters < 2 {
0.0
} else {
(self.flops_m2 / (self.n_iters - 1) as f64).sqrt()
}
}

/// Update running statistics + Welford's algorithm for variance
fn update_flops(&mut self, flops: usize) {
self.flops_max = self.flops_max.max(flops);
self.flops_min = self.flops_min.min(flops);
self.flops_sum += flops;
self.n_iters += 1;

let flops_f64 = flops as f64;
let delta = flops_f64 - self.flops_mean;
self.flops_mean += delta / self.n_iters as f64;
let delta2 = flops_f64 - self.flops_mean;
self.flops_m2 += delta * delta2;
}

fn is_throttled(&self) -> bool {
self.throttling_hw > 0 || self.throttling_thermal_sw > 0 || self.throttling_thermal_hw > 0
}
Expand All @@ -126,6 +150,8 @@ impl Default for BurnResult {
flops_max: 0,
flops_min: usize::MAX,
flops_sum: 0,
flops_mean: 0.0,
flops_m2: 0.0,
n_iters: 0,
temp_max: 0,
temp_sum: 0,
Expand Down Expand Up @@ -472,11 +498,8 @@ async fn report_progress(
}

if tick > 4 {
// Skip the first 4 ticks to avoid caches effects
burn_results[i].flops_max = burn_results[i].flops_max.max(flops);
burn_results[i].flops_min = burn_results[i].flops_min.min(flops);
burn_results[i].flops_sum += flops;
burn_results[i].n_iters += 1;
// Skip the first 5 ticks to avoid caches effects
burn_results[i].update_flops(flops);
}
}
// Report GPU temperatures
Expand Down Expand Up @@ -531,7 +554,7 @@ async fn report_progress(
r.flops_avg() / 1_000_000_000.0,
r.flops_min as f64 / 1_000_000_000.0,
r.flops_max as f64 / 1_000_000_000.0,
r.flops_avg() / 1_000_000_000.0
r.flops_stddev() / 1_000_000_000.0
);
println!(
" Temperature: {:.2}°C (min: {:.2}, max: {:.2})",
Expand Down
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