Index: sys/netinet/tcp_lro.c
===================================================================
--- sys/netinet/tcp_lro.c
+++ sys/netinet/tcp_lro.c
@@ -41,6 +41,7 @@
 #include <sys/mbuf.h>
 #include <sys/kernel.h>
 #include <sys/socket.h>
+#include <sys/sysctl.h>
 
 #include <net/if.h>
 #include <net/if_var.h>
@@ -53,6 +54,7 @@
 #include <netinet/ip.h>
 #include <netinet/ip_var.h>
 #include <netinet/tcp.h>
+#include <netinet/tcp_var.h>
 #include <netinet/tcp_lro.h>
 
 #include <netinet6/ip6_var.h>
@@ -66,6 +68,13 @@
 #define	TCP_LRO_INVALID_CSUM	0x0000
 #endif
 
+static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, lro,
+    CTLFLAG_RW, 0, "LRO parameters");
+
+static int tcp_lro_use_qsort;
+SYSCTL_INT(_net_inet_tcp_lro, OID_AUTO, use_qsort, CTLFLAG_RWTUN,
+    &tcp_lro_use_qsort, 0, "Set to use QuickSort else MergeSort is used");
+
 int
 tcp_lro_init(struct lro_ctrl *lc)
 {
@@ -92,7 +101,7 @@
 	SLIST_INIT(&lc->lro_active);
 
 	/* compute size to allocate */
-	size = (lro_mbufs * sizeof(struct mbuf *)) +
+	size = (2 * lro_mbufs * sizeof(struct mbuf *)) +
 	    (lro_entries * sizeof(*le));
 	lc->lro_mbuf_data = (struct mbuf **)
 	    malloc(size, M_LRO, M_NOWAIT | M_ZERO);
@@ -104,7 +113,7 @@
 	}
 	/* compute offset for LRO entries */
 	le = (struct lro_entry *)
-	    (lc->lro_mbuf_data + lro_mbufs);
+	    (lc->lro_mbuf_data + 2 * lro_mbufs);
 
 	/* setup linked list */
 	for (i = 0; i != lro_entries; i++)
@@ -340,19 +349,26 @@
 {
 	const struct mbuf *ma = *((const struct mbuf * const *)ppa);
 	const struct mbuf *mb = *((const struct mbuf * const *)ppb);
-	int ret;
+	int64_t ret;
 
 	ret = M_HASHTYPE_GET(ma) - M_HASHTYPE_GET(mb);
 	if (ret != 0)
 		goto done;
 
-	ret = ma->m_pkthdr.flowid - mb->m_pkthdr.flowid;
+	ret = ((uint64_t)(uint32_t)ma->m_pkthdr.flowid) -
+	    ((uint64_t)(uint32_t)mb->m_pkthdr.flowid);
 	if (ret != 0)
 		goto done;
 
 	ret = TCP_LRO_SEQUENCE(ma) - TCP_LRO_SEQUENCE(mb);
+	if (ret != 0)
+		goto done;
+	return (0);
 done:
-	return (ret);
+	if (ret < 0)
+		return (-1);
+	else
+		return (1);
 }
 
 void
@@ -367,9 +383,14 @@
 	if (__predict_false(lc->lro_mbuf_count == 0))
 		goto done;
 
-	/* sort all mbufs according to stream */
-	qsort(lc->lro_mbuf_data, lc->lro_mbuf_count, sizeof(struct mbuf *),
-	    &tcp_lro_mbuf_compare_header);
+	if (__predict_false(tcp_lro_use_qsort)) {
+		qsort(lc->lro_mbuf_data, lc->lro_mbuf_count,
+		    sizeof(struct mbuf *), &tcp_lro_mbuf_compare_header);
+	} else {
+		mergesort_by_pointer((void **)lc->lro_mbuf_data,
+		    (void **)(lc->lro_mbuf_data + lc->lro_mbuf_count),
+		    lc->lro_mbuf_count, &tcp_lro_mbuf_compare_header);
+	}
 
 	/* input data into LRO engine, stream by stream */
 	flowid = 0;
@@ -391,10 +412,6 @@
 				tcp_lro_flush(lc, le);
 			}
 		}
-#ifdef TCP_LRO_RESET_SEQUENCE
-		/* reset sequence number */
-		TCP_LRO_SEQUENCE(mb) = 0;
-#endif
 		/* add packet to LRO engine */
 		if (tcp_lro_rx(lc, mb, 0) != 0) {
 			/* input packet to network layer */