Notes On Interruptthrottlerate - Supermicro AOC-SG-i2 User Manual

AOC-SG-i2 Add On Card User's Guide
Table 4-1. Command Line Parameter Settings (Continued)
Parameter Valid Range/
Name Settings
80-256 for 82542
and 82543-based
adapters
TxDescriptors
80-4096 for all
other supported
adapters
TxIntDelay 0-65535 (0=off)
TxAbsIntDelay 0-65535 (0=off)
XsumRX 0-1
1. InterruptThrottleRate takes precedence over the TxAbsIntDelay and RxAbsIntDelay
parameters. In other words, minimizing the receive and/or transmit absolute delays does
not force the controller to generate more interrupts than what the Interrupt Throttle Rate
allows.

Notes on InterruptThrottleRate

Since 7.3.x, the driver has two adaptive modes (setting 1 or 3) in which it dynamically
adjusts the InterruptThrottleRate value based on the traffic that it receives. After
determining the type of incoming traffic in the last time frame, it will adjust the
InterruptThrottleRate to an appropriate value for that traffic.
The algorithm classifies the incoming traffic every interval into classes. Once the class is
determined, the InterruptThrottleRate value is adjusted to suit that traffic type the best.
There are three classes defined: "Bulk traffic", for large amounts of packets of normal
size; "Low latency", for small amounts of traffic and/or a significant percentage of small
packets; and "Lowest latency", for almost completely small packets or minimal traffic.
Default Description
This value is the number of transmit descriptors
allocated by the driver. Increasing this value allows
256
the driver to queue more transmits. Each descriptor
is 16 bytes.
This value delays the generation of transmit
interrupts in units of 1.024 microseconds. Transmit
interrupt reduction can improve CPU efficiency if
64 properly tuned for specific network traffic. If the
system is reporting dropped transmits, this value
may be set too high causing the driver to run out of
available transmit descriptors.
This value, in units of 1.024 microseconds, limits
the delay in which a transmit interrupt is generated.
Useful only if TxIntDelay is non-zero, this value
ensures that an interrupt is generated after the
initial packet is sent on the wire within the set
64
amount of time. Proper tuning, along with
TxIntDelay, may improve traffic throughput in
specific network conditions.
This parameter is supported only on 82540, 82545
and later adapters.
A value of '1' indicates that the driver should enable
IP checksum offload for received packets (both
UDP and TCP) to the adapter hardware.
1
This parameter is not supported on the
82542-based adapter.
4-6