Parameter Name
Valid
Range/Settings
Default
Description
RSS
0 - 16
1
Receive Side Scaling allows multiple queues for receiving
data.
0 = Sets the descriptor queue count to the lower value of either
the number of CPUs or 16.
1 - 16 = Sets the descriptor queue count to 1 - 16.
RSS also effects the number of transmit queues allocated on
2.6.23 and newer kernels with CONFIG_NET_MULTIQUEUE
set in the kernel .config file. CONFIG_NETDEVICES_
MULTIQUEUE is only supported in kernels 2.6.23 to 2.6.26. For
kernels 2.6.27 or newer, other options enable multiqueue.
NOTE:
The RSS parameter has no effect on 82599-
based adapters unless the FdirMode parameter is sim-
ultaneously used to disable Flow Director. See
Intel®
Ethernet Flow Director
section for more detail.
MQ
0, 1
1
Multi Queue support.
0 = Disables Multiple Queue support.
1 = Enables Multiple Queue support (prerequisite for RSS).
IntMode
0 - 2
2
Interrupt mode controls the allowed load time control over the
type of interrupt registered for by the driver. MSI-X is required
for multiple queue support, and some kernels and com-
binations of kernel .config options will force a lower level of
interrupt support. 'cat /proc/interrupts' will show different values
for each type of interrupt.
0 = Legacy interrupt
1 = MSI
2 = MSIX
InterruptThrottleRate
956 - 488,281
(0=off, 1=d-
dynamic)
1
Interrupt Throttle Rate (interrupts/second). The ITR parameter
controls how many interrupts each interrupt vector can gen-
erate per second. Increasing ITR lowers latency at the cost of
increased CPU utilization, though it may help throughput in
some circumstances.
0 = This turns off any interrupt moderation and may improve
small packet latency. However, it is generally not suitable for
bulk throughput traffic due to the increased CPU utilization of
the higher interrupt rate.
NOTES:
l
For 82599-based adapters, disabling Inter-
ruptThrottleRate will also result in the driver dis-
abling HW RSC.
l
For 82598-based adapters, disabling Inter-
ruptThrottleRate will also result in disabling LRO.
1 = Dynamic mode attempts to moderate interrupts per vector
while maintaining very low latency. This can sometimes cause
extra CPU utilization when in dynamic mode. If planning on
deploying ixgbe in a latency sensitive environment, please con-
sider this parameter.
