Tuning Recommendations

The following tables provide recommendations for tuning settings for different applications.

Recommended Throughput Tuning

The following table shows recommended tuning settings for throughput.

Table 1. Throughput Tuning Settings
Tuning Parameter	How?
Interrupt moderation	Leave at default (Enabled).
TCP/IP checksum offload	Leave at default (Enabled).
TCP protocol tuning	Leave at default.
Interrupt affinity & irqbalance service	Interrupt affinity settings are application dependent Stop irqbalance service: `/sbin/service irqbalance stop` Reload the drivers to use the driver default interrupt affinity.
PCI Express lane configuration	Ensure the adapter is in an ×8 slot (3.0 or later), and that current speed (not the supported speed) reads back as “x8 and 8GT/s”, or “x8 and 16GT/s”, or “x8 and Unknown”.
CPU Speed service (cpuspeed)	Leave enabled.
Memory bandwidth	Ensure memory uses all memory channels on system motherboard.
Intel QuickData (Intel chipsets only)	Enable in BIOS and install driver: `modprobe ioatdma`

The following table shows recommended tuning settings for latency.

Table 2. Latency Tuning Settings
Tuning Parameter	How?
Interrupt moderation	Disable with: `ethtool -C <interface> rx-usecs-irq 0`
TCP/IP checksum offload	Leave at default (Enabled).
TCP protocol tuning	Leave at default, but changing does not impact latency.
Interrupt affinity & irqbalance service	Interrupt affinity settings are application dependent Stop irqbalance service: `/sbin/service irqbalance stop` Reload the drivers to use the driver default interrupt affinity.
PCI Express lane configuration	Ensure the adapter is in an ×8 slot (3.0 or later), and that current speed (not the supported speed) reads back as “x8 and 8GT/s”, or “x8 and 16GT/s”, or “x8 and Unknown”.
CPU Speed service (cpuspeed)	Disable with: `/sbin/service cpuspeed stop`
CPU Power service (cpupower)	Disable with: `systemctl stop cpupower systemctl disable cpupower`
Tuned service	Experiment disabling this with: `systemctl stop tuned systemctl disable tuned`
Memory bandwidth	Ensure memory uses all memory channels on system motherboard.
Intel QuickData (Intel chipsets only)	Enable in BIOS and install driver: `modprobe ioatdma`

The following table shows recommended tuning settings for forwarding.

Table 3. Forwarding Tuning Settings
Tuning Parameter	How?
TCP/IP checksum offload	Leave at default (Enabled).
TCP protocol tuning	Leave at default.
Interrupt affinity & irqbalance service	Interrupt affinity. Affinitize each interface to its own CPU (if possible select CPU's on the same package). Refer to Interrupt Affinity. Stop irqbalance service: `/sbin/service irqbalance stop`