Update benchmark/Benchmark.php

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: danielebarbaro

benchmark/Benchmark.php

@@ -428,15 +428,15 @@ private function benchmarkPersistence(array $documents, int $n): array
     private function buildSearchMetrics(array $measurement): array
     {
         $latencies = $measurement['latencies_ms'];
-        $count = count($latencies);
+        sort($latencies, SORT_NUMERIC);
 
         return [
             'operations' => $this->queries,
             'total_time_s' => $measurement['elapsed_seconds'],
             'qps' => $this->queries / $measurement['elapsed_seconds'],
-            'latency_p50_ms' => $latencies[(int) ($count * 0.50)],
-            'latency_p95_ms' => $latencies[(int) ($count * 0.95)],
-            'latency_p99_ms' => $latencies[(int) ($count * 0.99)],
+            'latency_p50_ms' => Stats::percentile($latencies, 50.0),
+            'latency_p95_ms' => Stats::percentile($latencies, 95.0),
+            'latency_p99_ms' => Stats::percentile($latencies, 99.0),
             'memory_delta_mb' => $measurement['memory_delta_mb'],
             'memory_current_mb' => $measurement['memory_current_mb'],
         ];