User Manual

Rev 2.1-1.0.6
Mellanox Technologies
133
7.2.5 Interrupt Moderation
Interrupt moderation is used to decrease the frequency of network adapter interrupts to the CPU.
Mellanox network adapters use an adaptive interrupt moderation algorithm by default. The algo-
rithm checks the transmission (Tx) and receive (Rx) packet rates and modifies the Rx interrupt
moderation settings accordingly.
To manually set Tx and/or Rx interrupt moderation, use the ethtool utility. For example, the fol-
lowing commands first show the current (default) setting of interrupt moderation on the interface
eth1, then turns off Rx interrupt moderation, and last shows the new setting.
7.2.6 Tuning for NUMA Architecture
7.2.6.1 Tuning for Intel® Sandy Bridge Platform
The Intel Sandy Bridge processor has an integrated PCI express controller. Thus every PCIe
adapter OS is connected directly to a NUMA node.
On a system with more than one NUMA node, performance will be better when using the local
NUMA node to which the PCIe adapter is connected.
In order to identify which NUMA node is the adapter's node the system BIOS should support
ACPI SLIT.
 To see if your system supports PCIe adapter's NUMA node detection:
> ethtool -c eth1
Coalesce parameters for eth1:
Adaptive RX: on TX: off
...
pkt-rate-low: 400000
pkt-rate-high: 450000
rx-usecs: 16
rx-frames: 88
rx-usecs-irq: 0
rx-frames-irq: 0
...
> ethtool -C eth1 adaptive-rx off rx-usecs 0 rx-frames 0
> ethtool -c eth1
Coalesce parameters for eth1:
Adaptive RX: off TX: off
...
pkt-rate-low: 400000
pkt-rate-high: 450000
rx-usecs: 0
rx-frames: 0
rx-usecs-irq: 0
rx-frames-irq: 0
...
# cat /sys/class/net/[interface]/device/numa_node
# cat /sys/devices/[PCI root]/[PCIe function]/numa_node