From 3d88ba35dd8958e274199857644b406090094bbc Mon Sep 17 00:00:00 2001
From: Simon Duquennoy <simon.duquennoy@ri.se>
Date: Fri, 25 May 2018 12:33:30 -0700
Subject: [PATCH] TSCH: keep track of max/min observed drift and log it
 periodically

---
 os/net/mac/tsch/tsch-adaptive-timesync.c | 6 +++++-
 os/net/mac/tsch/tsch.c                   | 4 ++++
 os/net/mac/tsch/tsch.h                   | 2 ++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/os/net/mac/tsch/tsch-adaptive-timesync.c b/os/net/mac/tsch/tsch-adaptive-timesync.c
index a23a4f1b0..6508a8752 100644
--- a/os/net/mac/tsch/tsch-adaptive-timesync.c
+++ b/os/net/mac/tsch/tsch-adaptive-timesync.c
@@ -109,7 +109,9 @@ timesync_learn_drift_ticks(uint32_t time_delta_asn, int32_t drift_ticks)
 
   TSCH_LOG_ADD(tsch_log_message,
       snprintf(log->message, sizeof(log->message),
-          "drift %ld", tsch_adaptive_timesync_get_drift_ppm()));
+          "drift %ld (min/max delta seen: %"PRId32"/%"PRId32")",
+          tsch_adaptive_timesync_get_drift_ppm(),
+          min_drift_seen, max_drift_seen));
 }
 /*---------------------------------------------------------------------------*/
 /* Either reset or update the neighbor's drift */
@@ -136,6 +138,8 @@ tsch_timesync_update(struct tsch_neighbor *n, uint16_t time_delta_asn, int32_t d
       compensated_ticks += drift_correction;
     }
   }
+  min_drift_seen = MIN(drift_correction, min_drift_seen);
+  max_drift_seen = MAX(drift_correction, max_drift_seen);
 }
 /*---------------------------------------------------------------------------*/
 /* Error-accumulation free compensation algorithm */
diff --git a/os/net/mac/tsch/tsch.c b/os/net/mac/tsch/tsch.c
index dea750120..45df20e6f 100644
--- a/os/net/mac/tsch/tsch.c
+++ b/os/net/mac/tsch/tsch.c
@@ -160,6 +160,8 @@ static struct ctimer keepalive_timer;
 unsigned long tx_count;
 unsigned long rx_count;
 unsigned long sync_count;
+int32_t min_drift_seen;
+int32_t max_drift_seen;
 
 /* TSCH processes and protothreads */
 PT_THREAD(tsch_scan(struct pt *pt));
@@ -648,6 +650,8 @@ tsch_associate(const struct input_packet *input_eb, rtimer_clock_t timestamp)
       tx_count = 0;
       rx_count = 0;
       sync_count = 0;
+      min_drift_seen = 0;
+      max_drift_seen = 0;
 
       /* Start sending keep-alives now that tsch_is_associated is set */
       tsch_schedule_keepalive();
diff --git a/os/net/mac/tsch/tsch.h b/os/net/mac/tsch/tsch.h
index 93b6e0d88..88ebb4db6 100644
--- a/os/net/mac/tsch/tsch.h
+++ b/os/net/mac/tsch/tsch.h
@@ -175,6 +175,8 @@ extern rtimer_clock_t tsch_timing[tsch_ts_elements_count];
 extern unsigned long tx_count;
 extern unsigned long rx_count;
 extern unsigned long sync_count;
+extern int32_t min_drift_seen;
+extern int32_t max_drift_seen;
 
 /* TSCH processes */
 PROCESS_NAME(tsch_process);