Index: ifq.c
===================================================================
RCS file: /cvs/src/sys/net/ifq.c,v
retrieving revision 1.49
diff -u -p -r1.49 ifq.c
--- ifq.c	9 Jan 2023 03:39:14 -0000	1.49
+++ ifq.c	15 May 2023 02:57:16 -0000
@@ -78,6 +78,22 @@ void	ifq_restart_task(void *);
 void	ifq_barrier_task(void *);
 void	ifq_bundle_task(void *);
 
+static void
+ifq_senter(struct ifqueue *ifq)
+{
+	if (!mtx_enter_try(&ifq->ifq_task_mtx)) {
+		mtx_enter(&ifq->ifq_task_mtx);
+		ifq->ifq_scontended++;
+	}
+	ifq->ifq_slocks++;
+}
+
+static inline void
+ifq_sleave(struct ifqueue *ifq)
+{
+	mtx_leave(&ifq->ifq_task_mtx);
+}
+
 static inline void
 ifq_run_start(struct ifqueue *ifq)
 {
@@ -92,7 +108,7 @@ ifq_serialize(struct ifqueue *ifq, struc
 	if (ISSET(t->t_flags, TASK_ONQUEUE))
 		return;
 
-	mtx_enter(&ifq->ifq_task_mtx);
+	ifq_senter(ifq);
 	if (!ISSET(t->t_flags, TASK_ONQUEUE)) {
 		SET(t->t_flags, TASK_ONQUEUE);
 		TAILQ_INSERT_TAIL(&ifq->ifq_task_list, t, t_entry);
@@ -106,16 +122,16 @@ ifq_serialize(struct ifqueue *ifq, struc
 			CLR(t->t_flags, TASK_ONQUEUE);
 			work = *t; /* copy to caller to avoid races */
 
-			mtx_leave(&ifq->ifq_task_mtx);
+			ifq_sleave(ifq);
 
 			(*work.t_func)(work.t_arg);
 
-			mtx_enter(&ifq->ifq_task_mtx);
+			ifq_senter(ifq);
 		}
 
 		ifq->ifq_serializer = NULL;
 	}
-	mtx_leave(&ifq->ifq_task_mtx);
+	ifq_sleave(ifq);
 }
 
 int
@@ -202,6 +218,11 @@ struct ifq_kstat_data {
 	struct kstat_kv kd_qlen;
 	struct kstat_kv kd_maxqlen;
 	struct kstat_kv kd_oactive;
+
+	struct kstat_kv kd_qlocks;
+	struct kstat_kv kd_qcontended;
+	struct kstat_kv kd_slocks;
+	struct kstat_kv kd_scontended;
 };
 
 static const struct ifq_kstat_data ifq_kstat_tpl = {
@@ -218,6 +239,11 @@ static const struct ifq_kstat_data ifq_k
 	KSTAT_KV_UNIT_INITIALIZER("maxqlen",
 	    KSTAT_KV_T_UINT32, KSTAT_KV_U_PACKETS),
 	KSTAT_KV_INITIALIZER("oactive", KSTAT_KV_T_BOOL),
+
+	KSTAT_KV_INITIALIZER("qlocks", KSTAT_KV_T_COUNTER64),
+	KSTAT_KV_INITIALIZER("qcontended", KSTAT_KV_T_COUNTER64),
+	KSTAT_KV_INITIALIZER("slocks", KSTAT_KV_T_COUNTER64),
+	KSTAT_KV_INITIALIZER("scontended", KSTAT_KV_T_COUNTER64),
 };
 
 int
@@ -235,6 +261,11 @@ ifq_kstat_copy(struct kstat *ks, void *d
 	kstat_kv_u32(&kd->kd_maxqlen) = ifq->ifq_maxlen;
 	kstat_kv_bool(&kd->kd_oactive) = ifq->ifq_oactive;
 
+	kstat_kv_u64(&kd->kd_qlocks) = ifq->ifq_qlocks;
+	kstat_kv_u64(&kd->kd_qcontended) = ifq->ifq_qcontended;
+	kstat_kv_u64(&kd->kd_slocks) = ifq->ifq_slocks;
+	kstat_kv_u64(&kd->kd_scontended) = ifq->ifq_scontended;
+
 	return (0);
 }
 #endif
@@ -287,6 +318,22 @@ ifq_init(struct ifqueue *ifq, struct ifn
 #endif
 }
 
+static void
+ifq_qenter(struct ifqueue *ifq)
+{
+	if (!mtx_enter_try(&ifq->ifq_mtx)) {
+		mtx_enter(&ifq->ifq_mtx);
+		ifq->ifq_qcontended++;
+	}
+	ifq->ifq_qlocks++;
+}
+
+static inline void
+ifq_qleave(struct ifqueue *ifq)
+{
+	mtx_leave(&ifq->ifq_mtx);
+}
+
 void
 ifq_attach(struct ifqueue *ifq, const struct ifq_ops *newops, void *opsarg)
 {
@@ -298,7 +345,7 @@ ifq_attach(struct ifqueue *ifq, const st
 
 	newq = newops->ifqop_alloc(ifq->ifq_idx, opsarg);
 
-	mtx_enter(&ifq->ifq_mtx);
+	ifq_qenter(ifq);
 	ifq->ifq_ops->ifqop_purge(ifq, &ml);
 	ifq->ifq_len = 0;
 
@@ -316,7 +363,7 @@ ifq_attach(struct ifqueue *ifq, const st
 		} else
 			ifq->ifq_len++;
 	}
-	mtx_leave(&ifq->ifq_mtx);
+	ifq_qleave(ifq);
 
 	oldops->ifqop_free(ifq->ifq_idx, oldq);
 
@@ -361,7 +408,7 @@ ifq_enqueue(struct ifqueue *ifq, struct 
 {
 	struct mbuf *dm;
 
-	mtx_enter(&ifq->ifq_mtx);
+	ifq_qenter(ifq);
 	dm = ifq->ifq_ops->ifqop_enq(ifq, m);
 	if (dm != m) {
 		ifq->ifq_packets++;
@@ -374,7 +421,7 @@ ifq_enqueue(struct ifqueue *ifq, struct 
 		ifq->ifq_len++;
 	else
 		ifq->ifq_qdrops++;
-	mtx_leave(&ifq->ifq_mtx);
+	ifq_qleave(ifq);
 
 	if (dm != NULL)
 		m_freem(dm);
@@ -385,7 +432,7 @@ ifq_enqueue(struct ifqueue *ifq, struct 
 static inline void
 ifq_deq_enter(struct ifqueue *ifq)
 {
-	mtx_enter(&ifq->ifq_mtx);
+	ifq_qenter(ifq);
 }
 
 static inline void
@@ -396,7 +443,7 @@ ifq_deq_leave(struct ifqueue *ifq)
 	ml = ifq->ifq_free;
 	ml_init(&ifq->ifq_free);
 
-	mtx_leave(&ifq->ifq_mtx);
+	ifq_qleave(ifq);
 
 	if (!ml_empty(&ml))
 		ml_purge(&ml);
@@ -518,12 +565,12 @@ ifq_purge(struct ifqueue *ifq)
 	struct mbuf_list ml = MBUF_LIST_INITIALIZER();
 	unsigned int rv;
 
-	mtx_enter(&ifq->ifq_mtx);
+	ifq_qenter(ifq);
 	ifq->ifq_ops->ifqop_purge(ifq, &ml);
 	rv = ifq->ifq_len;
 	ifq->ifq_len = 0;
 	ifq->ifq_qdrops += rv;
-	mtx_leave(&ifq->ifq_mtx);
+	ifq_qleave(ifq);
 
 	KASSERT(rv == ml_len(&ml));
 
@@ -586,6 +633,9 @@ struct ifiq_kstat_data {
 
 	struct kstat_kv kd_enqueues;
 	struct kstat_kv kd_dequeues;
+
+	struct kstat_kv kd_qlocks;
+	struct kstat_kv kd_qcontended;
 };
 
 static const struct ifiq_kstat_data ifiq_kstat_tpl = {
@@ -606,6 +656,11 @@ static const struct ifiq_kstat_data ifiq
 	    KSTAT_KV_T_COUNTER64),
 	KSTAT_KV_INITIALIZER("dequeues",
 	    KSTAT_KV_T_COUNTER64),
+
+	KSTAT_KV_INITIALIZER("qlocks",
+	    KSTAT_KV_T_COUNTER64),
+	KSTAT_KV_INITIALIZER("qcontended",
+	    KSTAT_KV_T_COUNTER64),
 };
 
 int
@@ -625,6 +680,9 @@ ifiq_kstat_copy(struct kstat *ks, void *
 	kstat_kv_u64(&kd->kd_enqueues) = ifiq->ifiq_enqueues;
 	kstat_kv_u64(&kd->kd_dequeues) = ifiq->ifiq_dequeues;
 
+	kstat_kv_u64(&kd->kd_qlocks) = ifiq->ifiq_qlocks;
+	kstat_kv_u64(&kd->kd_qcontended) = ifiq->ifiq_qcontended;
+
 	return (0);
 }
 #endif
@@ -649,6 +707,12 @@ ifiq_init(struct ifiqueue *ifiq, struct 
 	ifiq->ifiq_qdrops = 0;
 	ifiq->ifiq_errors = 0;
 
+	ifiq->ifiq_enqueues = 0;
+	ifiq->ifiq_dequeues = 0;
+
+	ifiq->ifiq_qlocks = 0;
+	ifiq->ifiq_qcontended = 0;
+
 	ifiq->ifiq_idx = idx;
 
 #if NKSTAT > 0
@@ -679,6 +743,22 @@ ifiq_destroy(struct ifiqueue *ifiq)
 	ml_purge(&ifiq->ifiq_ml);
 }
 
+static void
+ifiq_qenter(struct ifiqueue *ifiq)
+{
+	if (!mtx_enter_try(&ifiq->ifiq_mtx)) {
+		mtx_enter(&ifiq->ifiq_mtx);
+		ifiq->ifiq_qcontended++;
+	}
+	ifiq->ifiq_qlocks++;
+}
+
+static inline void
+ifiq_qleave(struct ifiqueue *ifiq)
+{
+	mtx_leave(&ifiq->ifiq_mtx);
+}
+
 unsigned int ifiq_maxlen_drop = 2048 * 5;
 unsigned int ifiq_maxlen_return = 2048 * 3;
 
@@ -721,18 +801,18 @@ ifiq_input(struct ifiqueue *ifiq, struct
 		}
 
 		if (ml_empty(ml)) {
-			mtx_enter(&ifiq->ifiq_mtx);
+			ifiq_qenter(ifiq);
 			ifiq->ifiq_packets += packets;
 			ifiq->ifiq_bytes += bytes;
 			ifiq->ifiq_fdrops += fdrops;
-			mtx_leave(&ifiq->ifiq_mtx);
+			ifiq_qleave(ifiq);
 
 			return (0);
 		}
 	}
 #endif
 
-	mtx_enter(&ifiq->ifiq_mtx);
+	ifiq_qenter(ifiq);
 	ifiq->ifiq_packets += packets;
 	ifiq->ifiq_bytes += bytes;
 	ifiq->ifiq_fdrops += fdrops;
@@ -746,7 +826,7 @@ ifiq_input(struct ifiqueue *ifiq, struct
 			ml_enlist(&ifiq->ifiq_ml, ml);
 		}
 	}
-	mtx_leave(&ifiq->ifiq_mtx);
+	ifiq_qleave(ifiq);
 
 	if (ml_empty(ml))
 		task_add(ifiq->ifiq_softnet, &ifiq->ifiq_task);
@@ -781,11 +861,11 @@ ifiq_enqueue(struct ifiqueue *ifiq, stru
 	if_bpf = ifp->if_bpf;
 	if (if_bpf) {
 		if ((*ifp->if_bpf_mtap)(if_bpf, m, BPF_DIRECTION_IN)) {
-			mtx_enter(&ifiq->ifiq_mtx);
+			ifiq_qenter(ifiq);
 			ifiq->ifiq_packets++;
 			ifiq->ifiq_bytes += m->m_pkthdr.len;
 			ifiq->ifiq_fdrops++;
-			mtx_leave(&ifiq->ifiq_mtx);
+			ifiq_qleave(ifiq);
 
 			m_freem(m);
 			return (0);
@@ -793,12 +873,12 @@ ifiq_enqueue(struct ifiqueue *ifiq, stru
 	}
 #endif
 
-	mtx_enter(&ifiq->ifiq_mtx);
+	ifiq_qenter(ifiq);
 	ifiq->ifiq_packets++;
 	ifiq->ifiq_bytes += m->m_pkthdr.len;
 	ifiq->ifiq_enqueues++;
 	ml_enqueue(&ifiq->ifiq_ml, m);
-	mtx_leave(&ifiq->ifiq_mtx);
+	ifiq_qleave(ifiq);
 
 	task_add(ifiq->ifiq_softnet, &ifiq->ifiq_task);
 
@@ -814,11 +894,11 @@ ifiq_process(void *arg)
 	if (ifiq_empty(ifiq))
 		return;
 
-	mtx_enter(&ifiq->ifiq_mtx);
+	ifiq_qenter(ifiq);
 	ifiq->ifiq_dequeues++;
 	ml = ifiq->ifiq_ml;
 	ml_init(&ifiq->ifiq_ml);
-	mtx_leave(&ifiq->ifiq_mtx);
+	ifiq_qleave(ifiq);
 
 	if_input_process(ifiq->ifiq_if, &ml);
 }
Index: ifq.h
===================================================================
RCS file: /cvs/src/sys/net/ifq.h,v
retrieving revision 1.37
diff -u -p -r1.37 ifq.h
--- ifq.h	9 Jan 2023 03:37:44 -0000	1.37
+++ ifq.h	15 May 2023 02:57:16 -0000
@@ -55,6 +55,11 @@ struct ifqueue {
 	uint64_t		 ifq_errors;
 	uint64_t		 ifq_mcasts;
 
+	uint64_t		 ifq_qlocks;
+	uint64_t		 ifq_qcontended;
+	uint64_t		 ifq_slocks;
+	uint64_t		 ifq_scontended;
+
 	struct kstat		*ifq_kstat;
 
 	/* work serialisation */
@@ -100,6 +105,9 @@ struct ifiqueue {
 	uint64_t		 ifiq_enqueues;
 	/* number of times a list of packets were pulled off ifiq_ml */
 	uint64_t		 ifiq_dequeues;
+
+	uint64_t		 ifiq_qlocks;
+	uint64_t		 ifiq_qcontended;
 
 	struct kstat		*ifiq_kstat;