From cf1344f6fcb8403b92fae89fcc2a4474501b06ad Mon Sep 17 00:00:00 2001
From: David Greenman <dg@FreeBSD.org>
Date: Sat, 6 Aug 1994 11:26:16 +0000
Subject: [PATCH] Implemented "fast" mbuf macros. a small number of mbufs are
 cached in a linked list for fast allocation/free. Improves TCP performance by
 about 20%.

Submitted by:	John Dyson
---
 sys/sys/mbuf.h | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 681b289e2d0..47ab7f5009c 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)mbuf.h	8.3 (Berkeley) 1/21/94
- * $Id$
+ * $Id: mbuf.h,v 1.2 1994/08/02 07:53:12 davidg Exp $
  */
 
 #ifndef M_WAITOK
@@ -168,8 +168,19 @@ struct mbuf {
  * allocates an mbuf and initializes it to contain a packet header
  * and internal data.
  */
+struct mbuf *mbuffree;
+int mbuffreecnt;
 #define	MGET(m, how, type) { \
-	MALLOC((m), struct mbuf *, MSIZE, mbtypes[type], (how)); \
+	int s = splimp(); \
+	if (mbuffree == 0) { \
+		splx(s); \
+		MALLOC((m), struct mbuf *, MSIZE, mbtypes[type], (how)); \
+	} else { \
+		--mbuffreecnt; \
+		(m) = mbuffree; \
+		mbuffree = (m)->m_next; \
+		splx(s); \
+	} \
 	if (m) { \
 		(m)->m_type = (type); \
 		MBUFLOCK(mbstat.m_mtypes[type]++;) \
@@ -182,7 +193,16 @@ struct mbuf {
 }
 
 #define	MGETHDR(m, how, type) { \
-	MALLOC((m), struct mbuf *, MSIZE, mbtypes[type], (how)); \
+	int s = splimp(); \
+	if (mbuffree == 0) { \
+		splx(s); \
+		MALLOC((m), struct mbuf *, MSIZE, mbtypes[type], (how)); \
+	} else { \
+		--mbuffreecnt; \
+		(m) = mbuffree; \
+		mbuffree = (m)->m_next; \
+		splx(s); \
+	} \
 	if (m) { \
 		(m)->m_type = (type); \
 		MBUFLOCK(mbstat.m_mtypes[type]++;) \
@@ -265,7 +285,15 @@ union mcluster {
 		MCLFREE((m)->m_ext.ext_buf); \
 	  } \
 	  (nn) = (m)->m_next; \
-	  FREE((m), mbtypes[(m)->m_type]); \
+	  if (mbuffreecnt < 256) { \
+		int s = splimp(); \
+		++mbuffreecnt; \
+		(m)->m_next = mbuffree; \
+		mbuffree = (m); \
+		splx(s); \
+	  } else { \
+	  	FREE((m), mbtypes[(m)->m_type]); \
+	  } \
 	}
 #endif