From: Eric Dumazet Date: Sun, 23 Sep 2012 22:28:59 +0000 (+0000) Subject: net: loopback: set default mtu to 64K X-Git-Tag: upstream/snapshot3+hdmi~6565^2~85 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0cf833aefaa85bbfce3ff70485e5534e09254773;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git net: loopback: set default mtu to 64K loopback current mtu of 16436 bytes allows no more than 3 MSS TCP segments per frame, or 48 Kbytes. Changing mtu to 64K allows TCP stack to build large frames and significantly reduces stack overhead. Performance boost on bulk TCP transferts can be up to 30 %, partly because we now have one ACK message for two 64KB segments, and a lower probability of hitting /proc/sys/net/ipv4/tcp_reordering default limit. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c index 4a075ba..81f8f9e 100644 --- a/drivers/net/loopback.c +++ b/drivers/net/loopback.c @@ -157,7 +157,7 @@ static const struct net_device_ops loopback_ops = { */ static void loopback_setup(struct net_device *dev) { - dev->mtu = (16 * 1024) + 20 + 20 + 12; + dev->mtu = 64 * 1024; dev->hard_header_len = ETH_HLEN; /* 14 */ dev->addr_len = ETH_ALEN; /* 6 */ dev->tx_queue_len = 0;