diff -r e2f4eac691d6 sys/net/if_wg.c
--- a/sys/net/if_wg.c	Fri Sep 11 20:25:12 2020 +0000
+++ b/sys/net/if_wg.c	Fri Sep 11 21:29:43 2020 +0000
@@ -45,6 +45,7 @@
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
+#include "opt_altq_enabled.h"
 #endif
 
 #include <sys/param.h>
@@ -703,6 +704,9 @@ static void	wg_input(struct ifnet *, str
 static int	wg_ioctl(struct ifnet *, u_long, void *);
 static int	wg_bind_port(struct wg_softc *, const uint16_t);
 static int	wg_init(struct ifnet *);
+#ifdef ALTQ
+static void	wg_start(struct ifnet *);
+#endif
 static void	wg_stop(struct ifnet *, int);
 
 static void	wg_peer_work(struct work *, void *);
@@ -3495,6 +3499,9 @@ wg_if_attach(struct wg_softc *wg)
 	wg->wg_if.if_ioctl = wg_ioctl;
 	wg->wg_if.if_output = wg_output;
 	wg->wg_if.if_init = wg_init;
+#ifdef ALTQ
+	wg->wg_if.if_start = wg_start;
+#endif
 	wg->wg_if.if_stop = wg_stop;
 	wg->wg_if.if_type = IFT_OTHER;
 	wg->wg_if.if_dlt = DLT_NULL;
@@ -3740,7 +3747,12 @@ wg_output(struct ifnet *ifp, struct mbuf
 		goto out0;
 	}
 
-	IFQ_CLASSIFY(&ifp->if_snd, m, dst->sa_family);
+#ifdef ALTQ
+	bool altq = atomic_load_relaxed(&ifp->if_snd.altq_flags)
+	    & ALTQF_ENABLED;
+	if (altq)
+		IFQ_CLASSIFY(&ifp->if_snd, m, dst->sa_family);
+#endif
 
 	bpf_mtap_af(ifp, dst->sa_family, m, BPF_D_OUT);
 
@@ -3779,18 +3791,36 @@ wg_output(struct ifnet *ifp, struct mbuf
 	}
 
 	/* There's an established session.  Toss it in the queue.  */
+#ifdef ALTQ
+	if (altq) {
+		mutex_enter(ifp->if_snd.ifq_lock);
+		if (ALTQ_IS_ENABLED(&ifp->if_snd)) {
+			M_SETCTX(m, wgp);
+			ALTQ_ENQUEUE(&ifp->if_snd, m, error);
+			m = NULL; /* consume */
+		}
+		mutex_exit(ifp->if_snd.ifq_lock);
+		if (m == NULL) {
+			wg_start(ifp);
+			goto out2;
+		}
+	}
+#endif
 	kpreempt_disable();
 	const uint32_t h = curcpu()->ci_index;	// pktq_rps_hash(m)
 	M_SETCTX(m, wgp);
 	if (__predict_false(!pktq_enqueue(wg_pktq, m, h))) {
 		WGLOG(LOG_ERR, "pktq full, dropping\n");
 		error = ENOBUFS;
-		goto out2;
+		goto out3;
 	}
 	m = NULL;		/* consumed */
 	error = 0;
-out2:	kpreempt_enable();
-
+out3:	kpreempt_enable();
+
+#ifdef ALTQ
+out2:
+#endif
 	wg_put_session(wgs, &wgs_psref);
 out1:	wg_put_peer(wgp, &wgp_psref);
 out0:	if (m)
@@ -4646,6 +4676,28 @@ wg_init(struct ifnet *ifp)
 	return 0;
 }
 
+#ifdef ALTQ
+static void
+wg_start(struct ifnet *ifp)
+{
+	struct mbuf *m;
+
+	for (;;) {
+		IFQ_DEQUEUE(&ifp->if_snd, m);
+		if (m == NULL)
+			break;
+
+		kpreempt_disable();
+		const uint32_t h = curcpu()->ci_index;	// pktq_rps_hash(m)
+		if (__predict_false(!pktq_enqueue(wg_pktq, m, h))) {
+			WGLOG(LOG_ERR, "pktq full, dropping\n");
+			m_freem(m);
+		}
+		kpreempt_enable();
+	}
+}
+#endif
+
 static void
 wg_stop(struct ifnet *ifp, int disable)
 {