HP NC-Series Mellanox Adapters Performance Tuning Guide

Performance tuning 5
Performance tuning
Linux
Use the Linux sysctl command to modify default system network parameters that are set by the operating
system to improve IPv4 and IPv6 traffic performance.
The sysctl settings below for IPv4 are also used for IPv6.
• Disable the TCP timestamps option for better cpu utilization:
sysctl -w net.ipv4.tcp_timestamps=0
• Disable the TCP selective acks option for better cpu utilization:
sysctl -w net.ipv4.tcp_sack=0
• Increase the maximum length of processor input queues:
sysctl -w net.core.netdev_max_backlog=250000
• Increase the TCP maximum and default buffer sizes using setsockopt():
sysctl -w net.core.rmem_max=16777216
sysctl -w net.core.wmem_max=16777216
sysctl -w net.core.rmem_default=16777216
sysctl -w net.core.wmem_default=16777216
sysctl -w net.core.optmem_max=16777216
• Increase memory thresholds to prevent packet dropping:
sysctl -w net.ipv4.tcp_mem="16777216 16777216 16777216"
• Increase Linux’s auto-tuning of TCP buffer limits. The minimum, default, and maximum number of
bytes to use are:
sysctl -w net.ipv4.tcp_rmem="4096 87380 16777216"
sysctl -w net.ipv4.tcp_wmem="4096 65536 16777216"
• Reduce the Transmit Queue Length to improve transmit throughput and increase the number of
connections:
ifconfig <interface> txqueuelen 100
Windows
To improve the network adapter performance, modify the registry entries as described below. Tuning is
needed only on one adapter and only once after the installation.
A reboot may be necessary for these changes to take effect.
Registry tuning on Windows Server 2008
Under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters:
• Disable tcp selective acks option for better cpu utilization:
SackOpts, type REG_DWORD, value set to 0.
Under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters: