From d6f79b2710ad919f911cffe2f54f51891c023111 Mon Sep 17 00:00:00 2001
From: Navdeep Parhar <np@FreeBSD.org>
Date: Mon, 3 Feb 2020 23:50:29 +0000
Subject: [PATCH] cxgbe(4): Avoid ext_arg2 in rxb_free.

ext_arg2 is the only item in the third cacheline in an mbuf and could be
cold by the time rxb_free runs.  Put the information needed by rxb_free
in the same line as the refcount, which is very likely to be hot given
that rxb_free runs when the refcount is decremented and reaches 0.

MFC after:	1 week
Sponsored by:	Chelsio Communications
---
 sys/dev/cxgbe/adapter.h |  2 ++
 sys/dev/cxgbe/t4_sge.c  | 15 +++++++++------
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/sys/dev/cxgbe/adapter.h b/sys/dev/cxgbe/adapter.h
index 31c2b403ede4..257e6bba50aa 100644
--- a/sys/dev/cxgbe/adapter.h
+++ b/sys/dev/cxgbe/adapter.h
@@ -326,6 +326,8 @@ struct cluster_layout {
 };
 
 struct cluster_metadata {
+	uma_zone_t zone;
+	caddr_t cl;
 	u_int refcount;
 };
 
diff --git a/sys/dev/cxgbe/t4_sge.c b/sys/dev/cxgbe/t4_sge.c
index fff9f7b77975..de8c44890639 100644
--- a/sys/dev/cxgbe/t4_sge.c
+++ b/sys/dev/cxgbe/t4_sge.c
@@ -1804,10 +1804,9 @@ cl_metadata(struct adapter *sc, struct sge_fl *fl, struct cluster_layout *cll,
 static void
 rxb_free(struct mbuf *m)
 {
-	uma_zone_t zone = m->m_ext.ext_arg1;
-	void *cl = m->m_ext.ext_arg2;
+	struct cluster_metadata *clm = m->m_ext.ext_arg1;
 
-	uma_zfree(zone, cl);
+	uma_zfree(clm->zone, clm->cl);
 	counter_u64_add(extfree_rels, 1);
 }
 
@@ -1880,10 +1879,12 @@ get_scatter_segment(struct adapter *sc, struct sge_fl *fl, int fr_offset,
 		fl->mbuf_inlined++;
 		if (sd->nmbuf++ == 0) {
 			clm->refcount = 1;
+			clm->zone = swz->zone;
+			clm->cl = sd->cl;
 			counter_u64_add(extfree_refs, 1);
 		}
-		m_extaddref(m, payload, blen, &clm->refcount, rxb_free,
-		    swz->zone, sd->cl);
+		m_extaddref(m, payload, blen, &clm->refcount, rxb_free, clm,
+		    NULL);
 	} else {
 
 		/*
@@ -1899,10 +1900,12 @@ get_scatter_segment(struct adapter *sc, struct sge_fl *fl, int fr_offset,
 		if (clm != NULL) {
 			if (sd->nmbuf++ == 0) {
 				clm->refcount = 1;
+				clm->zone = swz->zone;
+				clm->cl = sd->cl;
 				counter_u64_add(extfree_refs, 1);
 			}
 			m_extaddref(m, payload, blen, &clm->refcount,
-			    rxb_free, swz->zone, sd->cl);
+			    rxb_free, clm, NULL);
 		} else {
 			m_cljset(m, sd->cl, swz->type);
 			sd->cl = NULL;	/* consumed, not a recycle candidate */