sysctl configuration for 10GE ethernet

10G-sysctl.conf

#
# Based on info providef at http://fasterdata.es.net/
#

# allow testing with buffers up to 64MB
net.core.rmem_max = 67108864
net.core.wmem_max = 67108864

# Enable memory auto tuning
net.ipv4.tcp_moderate_rcvbuf = 1

# min, default, max number of bytes allocated for the socket's receive/send buffer
net.ipv4.tcp_rmem = 4096 87380 33554432
net.ipv4.tcp_wmem = 4096 65536 33554432

# recommended default congestion control is htcp
net.ipv4.tcp_congestion_control=htcp

# The maximum number of packets queued in received state
net.core.netdev_max_backlog = 30000

# Timeout closing of TCP connections after 7 seconds.
net.ipv4.tcp_fin_timeout = 7

# Avoid falling back to slow start after a connection goes idle.
net.ipv4.tcp_slow_start_after_idle = 0

# Enable Forward Acknowledgment, which operates with Selective Acknowledgment (SACK) to reduce congestion.
net.ipv4.tcp_fack = 1

# Support windows larger than 64KB.
net.ipv4.tcp_window_scaling = 1

# -- 10gbe tuning from Intel ixgb driver README -- #

# Enable selective acknowledgment, which improves performance by selectively acknowledging packets received out of order.
net.ipv4.tcp_sack = 0

# Enable calculation of RTT in a more accurate way (see RFC 1323) than the retransmission timeout.
net.ipv4.tcp_timestamps = 0

Be sure that net.core.netdev_budget is set to 300 as well:

net.core.netdev_budget_usecs = 2000
net.core.netdev_budget = 300

But in case softirqd processes shouldn't retrieve all packages from the interface in a single polling cycle, you might want to increase both the polling rate as well as the budget, to something like:

net.core.netdev_budget = 600
net.core.netdev_budget_usecs = 4000

More info and more info here