diff --git a/sys/netinet/tcp_stacks/rack.c b/sys/netinet/tcp_stacks/rack.c
--- a/sys/netinet/tcp_stacks/rack.c
+++ b/sys/netinet/tcp_stacks/rack.c
@@ -9176,6 +9176,7 @@
 		if ((rsm->r_flags & RACK_TO_REXT) &&
 		    (tp->t_flags & TF_RCVD_TSTMP) &&
 		    (to->to_flags & TOF_TS) &&
+		    (to->to_tsecr != 0) &&
 		    (tp->t_flags & TF_PREVVALID)) {
 			/*
 			 * We can use the timestamp to see
@@ -13321,7 +13322,7 @@
 	struct timespec ts;
 	struct tcp_rack *rack;
 	struct tcp_ackent *ae;
-	uint32_t tiwin, us_cts, cts, acked, acked_amount, high_seq, win_seq, the_win, win_upd_ack;
+	uint32_t tiwin, ms_cts, cts, acked, acked_amount, high_seq, win_seq, the_win, win_upd_ack;
 	int cnt, i, did_out, ourfinisacked = 0;
 	int win_up_req = 0;
 	struct tcpopt to_holder, *to = NULL;
@@ -13381,13 +13382,14 @@
 	the_win = tp->snd_wnd;
 	win_seq = tp->snd_wl1;
 	win_upd_ack = tp->snd_wl2;
-	cts = us_cts = tcp_tv_to_usectick(tv);
+	cts = tcp_tv_to_usectick(tv);
+	ms_cts = tcp_tv_to_mssectick(tv);
 	segsiz = ctf_fixed_maxseg(tp);
 	if ((rack->rc_gp_dyn_mul) &&
 	    (rack->use_fixed_rate == 0) &&
 	    (rack->rc_always_pace)) {
 		/* Check in on probertt */
-		rack_check_probe_rtt(rack, us_cts);
+		rack_check_probe_rtt(rack, cts);
 	}
 	for (i = 0; i < cnt; i++) {
 #ifdef TCP_ACCOUNTING
@@ -13424,8 +13426,8 @@
 			 * non RFC1323 RTT calculation.  Normalize timestamp if syncookies
 			 * were used when this connection was established.
 			 */
-			if (TSTMP_GT(ae->ts_echo, cts))
-				ae->ts_echo = 0;
+			if (TSTMP_GT(ae->ts_echo, ms_cts))
+				to->to_tsecr = 0;
 			if (tp->ts_recent &&
 			    TSTMP_LT(ae->ts_value, tp->ts_recent)) {
 				if (ctf_ts_check_ac(tp, (ae->flags & 0xff))) {
@@ -13524,7 +13526,6 @@
 			the_win = tiwin;
 		} else {
 			/* Case A */
-
 			if (SEQ_GT(ae->ack, tp->snd_max)) {
 				/*
 				 * We just send an ack since the incoming
@@ -13564,7 +13565,7 @@
 				}
 				rack_process_to_cumack(tp, rack, ae->ack, cts, to);
 				if (rack->rc_dsack_round_seen) {
-					/* Is the dsack roound over? */
+					/* Is the dsack round over? */
 					if (SEQ_GEQ(ae->ack, rack->r_ctl.dsack_round_end)) {
 						/* Yes it is */
 						rack->rc_dsack_round_seen = 0;
@@ -13687,7 +13688,7 @@
 
 			rack_ack_received(tp, rack, high_seq, nsegs, CC_ACK, recovery);
 			SOCKBUF_LOCK(&so->so_snd);
-			mfree = sbcut_locked(&so->so_snd, acked);
+			mfree = sbcut_locked(&so->so_snd, acked_amount);
 			tp->snd_una = high_seq;
 			/* Note we want to hold the sb lock through the sendmap adjust */
 			rack_adjust_sendmap(rack, &so->so_snd, tp->snd_una);
@@ -13962,7 +13963,12 @@
 #endif
 	int32_t thflags, retval, did_out = 0;
 	int32_t way_out = 0;
-	uint32_t cts;
+	/*
+	 * cts - is the current time from tv (caller gets ts) in microseconds.
+	 * ms_cts - is the current time from tv in milliseconds.
+	 * us_cts - is the time that LRO or hardware actually got the packet in microseconds.
+	 */
+	uint32_t cts, us_cts, ms_cts;
 	uint32_t tiwin;
 	struct timespec ts;
 	struct tcpopt to;
@@ -13973,19 +13979,19 @@
 	int ack_val_set = 0xf;
 #endif
 	int nsegs;
-	uint32_t us_cts;
 	/*
 	 * tv passed from common code is from either M_TSTMP_LRO or
 	 * tcp_get_usecs() if no LRO m_pkthdr timestamp is present.
 	 */
 	rack = (struct tcp_rack *)tp->t_fb_ptr;
-	cts = tcp_tv_to_usectick(tv);
 	if (m->m_flags & M_ACKCMP) {
 		return (rack_do_compressed_ack_processing(tp, so, m, nxt_pkt, tv));
 	}
 	if (m->m_flags & M_ACKCMP) {
 		panic("Impossible reach m has ackcmp? m:%p tp:%p", m, tp);
 	}
+	cts = tcp_tv_to_usectick(tv);
+	ms_cts =  tcp_tv_to_mssectick(tv);
 	nsegs = m->m_pkthdr.lro_nsegs;
 	counter_u64_add(rack_proc_non_comp_ack, 1);
 	thflags = th->th_flags;
@@ -14238,7 +14244,7 @@
 	 */
 	if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) {
 		to.to_tsecr -= tp->ts_offset;
-		if (TSTMP_GT(to.to_tsecr, cts))
+		if (TSTMP_GT(to.to_tsecr, ms_cts))
 			to.to_tsecr = 0;
 	}
 
@@ -15571,7 +15577,7 @@
 
 	soff = rack->r_ctl.fsb.off;
 	m = rack->r_ctl.fsb.m;
-	if (rack->r_ctl.fsb.o_m_len != m->m_len) {
+	if (rack->r_ctl.fsb.o_m_len > m->m_len) {
 		/*
 		 * The mbuf had the front of it chopped off by an ack
 		 * we need to adjust the soff/off by that difference.
@@ -15580,6 +15586,12 @@
 
 		delta = rack->r_ctl.fsb.o_m_len - m->m_len;
 		soff -= delta;
+	} else if (rack->r_ctl.fsb.o_m_len < m->m_len) {
+		/*
+		 * The mbuf was expanded probably by
+		 * a m_compress. Just update o_m_len.
+		 */
+		rack->r_ctl.fsb.o_m_len = m->m_len;
 	}
 	KASSERT(soff >= 0, ("%s, negative off %d", __FUNCTION__, soff));
 	KASSERT(*plen >= 0, ("%s, negative len %d", __FUNCTION__, *plen));