Why does my gigabit bond not deliver at least 150 MB/s throughput?
I had a similar problem trying to raise the speed of a drbd synchronization over two gigabit links some time ago. In the end I managed to get about 150MB/sec synch speed. These were the settings that I applied on both nodes:
ifconfig bond0 mtu 9000
ifconfig bond0 txqueuelen 10000
echo 3000 > /proc/sys/net/core/netdev_max_backlog
You could also try to enable interrupt coalescence if you don't already have for your network cards (with ethtool --coalesce)