git: 3034c0dab755 - stable/12 - Optimize TX coalescing by keeping pointer to last mbuf.

[Alexander Motin]

The branch stable/12 has been updated by mav:

URL: https://cgit.FreeBSD.org/src/commit/?id=3034c0dab755d29eb24d0187cfc00501b660a9c1

commit 3034c0dab755d29eb24d0187cfc00501b660a9c1
Author:     Alexander Motin <mav at FreeBSD.org>
AuthorDate: 2021-03-02 04:31:34 +0000
Commit:     Alexander Motin <mav at FreeBSD.org>
CommitDate: 2021-03-15 02:52:57 +0000

    Optimize TX coalescing by keeping pointer to last mbuf.
    
    Before m_cat() each time traversed through all the coalesced chain.
    
    MFC after:      1 week
    
    (cherry picked from commit b85a67f54a40053e75658a17c620b89bafaba67f)
---
 sys/dev/iscsi/icl_soft.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/sys/dev/iscsi/icl_soft.c b/sys/dev/iscsi/icl_soft.c
index caeddc9247ba..7c8ca11f4ae3 100644
--- a/sys/dev/iscsi/icl_soft.c
+++ b/sys/dev/iscsi/icl_soft.c
@@ -785,6 +785,7 @@ static void
 icl_conn_send_pdus(struct icl_conn *ic, struct icl_pdu_stailq *queue)
 {
 	struct icl_pdu *request, *request2;
+	struct mbuf *m;
 	struct socket *so;
 	long available, size, size2;
 	int coalesced, error;
@@ -845,8 +846,8 @@ icl_conn_send_pdus(struct icl_conn *ic, struct icl_pdu_stailq *queue)
 			return;
 		}
 		if (coalesce) {
-			coalesced = 1;
-			for (;;) {
+			m = request->ip_bhs_mbuf;
+			for (coalesced = 1; ; coalesced++) {
 				request2 = STAILQ_FIRST(queue);
 				if (request2 == NULL)
 					break;
@@ -863,13 +864,14 @@ icl_conn_send_pdus(struct icl_conn *ic, struct icl_pdu_stailq *queue)
 					icl_conn_fail(ic);
 					return;
 				}
-				m_cat(request->ip_bhs_mbuf, request2->ip_bhs_mbuf);
+				while (m->m_next)
+					m = m->m_next;
+				m_cat(m, request2->ip_bhs_mbuf);
 				request2->ip_bhs_mbuf = NULL;
 				request->ip_bhs_mbuf->m_pkthdr.len += size2;
 				size += size2;
 				STAILQ_REMOVE_AFTER(queue, request, ip_next);
 				icl_soft_conn_pdu_free(ic, request2);
-				coalesced++;
 			}
 #if 0
 			if (coalesced > 1) {