Seeing negative values for wlentime and rlentime

Linux kstat IO and TIMER printed values as signed. However the counters
only increment. Thus humans looking at the data can be confused when
the counters roll over.

Note: The recommended use of these values is to monitor the derivative,
which don't really care about the sign. See explanations related to
non-negative derivatives in the various time-series databases.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <guss80@gmail.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Richard Elling <Richard.Elling@RichardElling.com>
Closes #8131
Closes #8198

diff --git a/module/spl/spl-kstat.c b/module/spl/spl-kstat.c
index 8683693c8e6735cc047d76a3e1857ff185b60a19..7207a35e04bec2177c55ef71b612cc08f8759884 100644 (file)
--- a/module/spl/spl-kstat.c
+++ b/module/spl/spl-kstat.c
@@ -261,9 +261,10 @@ kstat_seq_show_intr(struct seq_file *f, kstat_intr_t *kip)
 static int
 kstat_seq_show_io(struct seq_file *f, kstat_io_t *kip)
 {
+       /* though wlentime & friends are signed, they will never be negative */
        seq_printf(f,
-           "%-8llu %-8llu %-8u %-8u %-8lld %-8lld "
-           "%-8lld %-8lld %-8lld %-8lld %-8u %-8u\n",
+           "%-8llu %-8llu %-8u %-8u %-8llu %-8llu "
+           "%-8llu %-8llu %-8llu %-8llu %-8u %-8u\n",
            kip->nread, kip->nwritten,
            kip->reads, kip->writes,
            kip->wtime, kip->wlentime, kip->wlastupdate,
@@ -277,7 +278,7 @@ static int
 kstat_seq_show_timer(struct seq_file *f, kstat_timer_t *ktp)
 {
        seq_printf(f,
-           "%-31s %-8llu %-8lld %-8lld %-8lld %-8lld %-8lld\n",
+           "%-31s %-8llu %-8llu %-8llu %-8llu %-8llu %-8llu\n",
            ktp->name, ktp->num_events, ktp->elapsed_time,
            ktp->min_time, ktp->max_time,
            ktp->start_time, ktp->stop_time);