bcachefs: time_stats: Check for last_event == 0 when updating freq stats

This fixes spurious outliers in the frequency stats.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c
index 56b815fd9fc6ee5a541aa8e7007f3c00025c493d..231003b405efc304a4cefa61a6e4e2f30b4b9466 100644 (file)
--- a/fs/bcachefs/util.c
+++ b/fs/bcachefs/util.c
@@ -418,14 +418,15 @@ static inline void bch2_time_stats_update_one(struct bch2_time_stats *stats,
                bch2_quantiles_update(&stats->quantiles, duration);
        }
 
-       if (time_after64(end, stats->last_event)) {
+       if (stats->last_event && time_after64(end, stats->last_event)) {
                freq = end - stats->last_event;
                mean_and_variance_update(&stats->freq_stats, freq);
                mean_and_variance_weighted_update(&stats->freq_stats_weighted, freq);
                stats->max_freq = max(stats->max_freq, freq);
                stats->min_freq = min(stats->min_freq, freq);
-               stats->last_event = end;
        }
+
+       stats->last_event = end;
 }
 
 static void __bch2_time_stats_clear_buffer(struct bch2_time_stats *stats,