Subject: [PATCH] ibmveth: Increase default copybreak limits to 2k

From: Robert Jennings <[email-masked]>
Date: Thu, 21 Oct 2010 09:37:53 -0500

Increase the copybreak limits for rx and tx from 128 bytes
to 2048 bytes. These limits were added by commits
8d86c61ae41d9068fd5e5cc01a4abd53c4fe3ab5 and
c08cc3ccebd46dce44d13a8ce81d249e687eeb8a to make use of a
bounce buffer for packets below 128 bytes.  This avoids
tearing down and creating a TCE entry.

Performance testing shows that this default limit can be
increased from 128 to 2048 for both rx and tx copybreak.
This resulted in ~10% throughput increase for for packets
that fit this limit without affecting performance for larger
packets.

Signed-off-by: Robert Jennings <[email-masked]>
---
 drivers/net/ibmveth.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ibmveth.c b/drivers/net/ibmveth.c
index c454b45..20b7a98 100644
--- a/drivers/net/ibmveth.c
+++ b/drivers/net/ibmveth.c
@@ -65,12 +65,12 @@ MODULE_DESCRIPTION("IBM Power Virtual Ethernet Driver");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(ibmveth_driver_version);
 
-static unsigned int tx_copybreak __read_mostly = 128;
+static unsigned int tx_copybreak __read_mostly = 2048;
 module_param(tx_copybreak, uint, 0644);
 MODULE_PARM_DESC(tx_copybreak,
 	"Maximum size of packet that is copied to a new buffer on transmit");
 
-static unsigned int rx_copybreak __read_mostly = 128;
+static unsigned int rx_copybreak __read_mostly = 2048;
 module_param(rx_copybreak, uint, 0644);
 MODULE_PARM_DESC(rx_copybreak,
 	"Maximum size of packet that is copied to a new buffer on receive");
-- 
1.7.0.4