stats: new trackers for lchan life duration (v2)

This patch adds two stats which track cummulative lchan lifetime by
type TCH and SDCCH. These new counters will accomplish two things:

1) Provide a glanceable way to see if lchan durations look healthy. When
examining a site, short-lived (<5s) and long-lived (>30s) TCH lchans
are difficult to tell apart. If we only see short-lived TCH lchans,
there is most likely an RF or signaling problem to investigate. This
new counter will expose channel ages in the VTY output

2) Provide a more accurate count for Erlangs per site. Currently, we
are basing Erlangs on active TCH channel counts per stats period. This
method skews high very quickly. Each active TCH in that period
translates into the full 10s of activity. This counter should improve
accuracy by two orders of magnitude.

Change-Id: Ie3771233ecbd4bc24a24fb22c1064a18e7b8b2b0

1 files changed, 16 insertions, 0 deletions

diff --git a/src/osmo-bsc/bsc_init.c b/src/osmo-bsc/bsc_init.c
index 0412f6b6b..650a76ba8 100644
--- a/src/osmo-bsc/bsc_init.c
+++ b/src/osmo-bsc/bsc_init.c
@@ -88,6 +88,18 @@ static void bsc_store_bts_uptime(void *data)
 	osmo_timer_schedule(&net->bts_store_uptime_timer, BTS_STORE_UPTIME_INTERVAL, 0);
 }
 
+static void bsc_store_bts_lchan_durations(void *data)
+{
+	struct gsm_network *net = data;
+	struct gsm_bts *bts;
+
+	llist_for_each_entry(bts, &net->bts_list, list)
+		bts_store_lchan_durations(bts);
+
+	/* Keep this timer ticking. */
+	osmo_timer_schedule(&net->bts_store_lchan_durations_timer, BTS_STORE_LCHAN_DURATIONS_INTERVAL, 0);
+}
+
 static struct gsm_network *bsc_network_init(void *ctx)
 {
 	struct gsm_network *net = gsm_network_init(ctx);
@@ -180,6 +192,10 @@ static struct gsm_network *bsc_network_init(void *ctx)
 	osmo_timer_setup(&net->bts_store_uptime_timer, bsc_store_bts_uptime, net);
 	osmo_timer_schedule(&net->bts_store_uptime_timer, BTS_STORE_UPTIME_INTERVAL, 0);
 
+	/* Init lchan duration tracking timer. */
+	osmo_timer_setup(&net->bts_store_lchan_durations_timer, bsc_store_bts_lchan_durations, net);
+	osmo_timer_schedule(&net->bts_store_lchan_durations_timer, BTS_STORE_LCHAN_DURATIONS_INTERVAL, 0);
+
 	net->cbc->net = net;
 	net->cbc->mode = BSC_CBC_LINK_MODE_DISABLED;
 	net->cbc->server.local_addr = bsc_cbc_default_server_local_addr;