bts: Add new stats to detect TBF allocation failure reasons

This is specially useful to detect for instance if a cell is handling
too many users, ending up in TFI or USF exhaustions. This information
can be later in the future used to tune TBF allocation algorithm behavior
(either manually/statially through config file, or
automatically/dynamically in code based on some thresholds).

Related: OS#5042
Change-Id: I5402e937ff8d800684655e500ef8e5c867141dc3

3 files changed, 15 insertions, 3 deletions

diff --git a/src/bts.cpp b/src/bts.cpp
index 8d1fb3f0..55d45b8c 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -100,7 +100,11 @@ static const struct rate_ctr_desc bts_ctr_description[] = {
 	{ "tbf:reused",			"TBF Reused           "},
 	{ "tbf:alloc:algo-a",		"TBF Alloc Algo A     "},
 	{ "tbf:alloc:algo-b",		"TBF Alloc Algo B     "},
-	{ "tbf:alloc:failed",		"TBF Alloc Failure    "},
+	{ "tbf:alloc:failed",		"TBF Alloc Failure (any reason)"},
+	{ "tbf:alloc:failed:no_tfi",	"TBF Alloc Failure (TFIs exhausted)"},
+	{ "tbf:alloc:failed:no_usf",	"TBF Alloc Failure (USFs exhausted)"},
+	{ "tbf:alloc:failed:no_slot_combi", "TBF Alloc Failure (No valid UL/DL slot combination found)"},
+	{ "tbf:alloc:failed:no_slot_avail", "TBF Alloc Failure (No slot available)"},
 	{ "rlc:sent",			"RLC Sent             "},
 	{ "rlc:resent",			"RLC Resent           "},
 	{ "rlc:restarted",		"RLC Restarted        "},
@@ -609,6 +613,7 @@ int bts_tfi_find_free(const struct gprs_rlcmac_bts *bts, enum gprs_rlcmac_tbf_di
 
 	if (best_trx_nr == 0xff || best_cnt == 0) {
 		LOGP(DRLCMAC, LOGL_NOTICE, "No TFI available (suggested TRX: %d).\n", use_trx);
+		bts_do_rate_ctr_inc(bts, CTR_TBF_ALLOC_FAIL_NO_TFI);
 		return -EBUSY;
 	}
 
diff --git a/src/bts.h b/src/bts.h
index d321b8d0..15a72bdc 100644
--- a/src/bts.h
+++ b/src/bts.h
@@ -88,6 +88,10 @@ enum {
 	CTR_TBF_ALLOC_ALGO_A,
 	CTR_TBF_ALLOC_ALGO_B,
 	CTR_TBF_ALLOC_FAIL,
+	CTR_TBF_ALLOC_FAIL_NO_TFI,
+	CTR_TBF_ALLOC_FAIL_NO_USF,
+	CTR_TBF_ALLOC_FAIL_NO_SLOT_COMBI,
+	CTR_TBF_ALLOC_FAIL_NO_SLOT_AVAIL,
 	CTR_RLC_SENT,
 	CTR_RLC_RESENT,
 	CTR_RLC_RESTARTED,
@@ -319,11 +323,11 @@ static inline struct osmo_stat_item_group *bts_stat_items(struct gprs_rlcmac_bts
 	return bts->statg;
 }
 
-static inline void bts_do_rate_ctr_inc(struct gprs_rlcmac_bts *bts, unsigned int ctr_id) {
+static inline void bts_do_rate_ctr_inc(const struct gprs_rlcmac_bts *bts, unsigned int ctr_id) {
 	rate_ctr_inc(&bts->ratectrs->ctr[ctr_id]);
 }
 
-static inline void bts_do_rate_ctr_add(struct gprs_rlcmac_bts *bts, unsigned int ctr_id, int inc) {
+static inline void bts_do_rate_ctr_add(const struct gprs_rlcmac_bts *bts, unsigned int ctr_id, int inc) {
 	rate_ctr_add(&bts->ratectrs->ctr[ctr_id], inc);
 }
 
diff --git a/src/gprs_rlcmac_ts_alloc.cpp b/src/gprs_rlcmac_ts_alloc.cpp
index 1dc31f6f..dd921e71 100644
--- a/src/gprs_rlcmac_ts_alloc.cpp
+++ b/src/gprs_rlcmac_ts_alloc.cpp
@@ -647,6 +647,7 @@ int find_multi_slots(struct gprs_rlcmac_trx *trx, uint8_t mslot_class, uint8_t *
 	if (!max_ul_slots || !max_dl_slots) {
 		LOGP(DRLCMAC, LOGL_NOTICE,
 			"No valid UL/DL slot combination found\n");
+		bts_do_rate_ctr_inc(trx->bts, CTR_TBF_ALLOC_FAIL_NO_SLOT_COMBI);
 		return -EINVAL;
 	}
 
@@ -719,6 +720,7 @@ static int tbf_select_slot_set(const gprs_rlcmac_tbf *tbf, const gprs_rlcmac_trx
 	if (!sl) {
 		LOGP(DRLCMAC, LOGL_NOTICE, "No %s slots available\n",
 		     tbf->direction != GPRS_RLCMAC_DL_TBF ? "uplink" : "downlink");
+		bts_do_rate_ctr_inc(trx->bts, CTR_TBF_ALLOC_FAIL_NO_SLOT_AVAIL);
 		return -EINVAL;
 	}
 
@@ -771,6 +773,7 @@ static int allocate_usf(const gprs_rlcmac_trx *trx, uint8_t selected_ul_slots, u
 
 	if (!ul_slots) {
 		LOGP(DRLCMAC, LOGL_NOTICE, "No USF available\n");
+		bts_do_rate_ctr_inc(trx->bts, CTR_TBF_ALLOC_FAIL_NO_USF);
 		return -EBUSY;
 	}