Author: arybchik
Date: Sat Feb 21 06:24:48 2015
New Revision: 279094
URL: https://svnweb.freebsd.org/changeset/base/279094
Log:
sfxge: more accurate calculation of maximum number of TSO segments
Sponsored by: Solarflare Communications, Inc.
Approved by: gnn (mentor)
Modified:
head/sys/dev/sfxge/sfxge_tx.c
head/sys/dev/sfxge/sfxge_tx.h
Modified: head/sys/dev/sfxge/sfxge_tx.c
==============================================================================
--- head/sys/dev/sfxge/sfxge_tx.c Sat Feb 21 06:05:51 2015
(r279093)
+++ head/sys/dev/sfxge/sfxge_tx.c Sat Feb 21 06:24:48 2015
(r279094)
@@ -72,10 +72,10 @@ __FBSDID("$FreeBSD$");
* maximum mbuf length we might need more than a ring-ful of
* descriptors, but this should not happen in practice except
* due to deliberate attack. In that case we will truncate
- * the output at a packet boundary. Allow for a reasonable
- * minimum MSS of 512.
+ * the output at a packet boundary.
*/
-#define SFXGE_TSO_MAX_DESC ((65535 / 512) * 2 +
SFXGE_TX_MAPPING_MAX_SEG - 1)
+#define SFXGE_TSO_MAX_DESC
\
+ (SFXGE_TSO_MAX_SEGS * 2 + SFXGE_TX_MAPPING_MAX_SEG - 1)
#define SFXGE_TXQ_BLOCK_LEVEL(_entries) ((_entries) -
SFXGE_TSO_MAX_DESC)
#ifdef SFXGE_HAVE_MQ
Modified: head/sys/dev/sfxge/sfxge_tx.h
==============================================================================
--- head/sys/dev/sfxge/sfxge_tx.h Sat Feb 21 06:05:51 2015
(r279093)
+++ head/sys/dev/sfxge/sfxge_tx.h Sat Feb 21 06:24:48 2015
(r279094)
@@ -36,12 +36,22 @@
#include <netinet/ip.h>
#include <netinet/tcp.h>
+/* Maximum size of TSO packet */
+#define SFXGE_TSO_MAX_SIZE (65535)
+
+/*
+ * Maximum number of segments to be created for a TSO packet.
+ * Allow for a reasonable minimum MSS of 512.
+ */
+#define SFXGE_TSO_MAX_SEGS howmany(SFXGE_TSO_MAX_SIZE, 512)
+
/* Maximum number of DMA segments needed to map an mbuf chain. With
* TSO, the mbuf length may be just over 64K, divided into 2K mbuf
* clusters. (The chain could be longer than this initially, but can
* be shortened with m_collapse().)
*/
-#define SFXGE_TX_MAPPING_MAX_SEG (64 / 2 + 1)
+#define SFXGE_TX_MAPPING_MAX_SEG
\
+ (1 + howmany(SFXGE_TSO_MAX_SIZE, MCLBYTES))
/*
* Buffer mapping flags.
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