Speed And Duplex Configuration - Supermicro AOC-SG-i2 User Manual

Chapter 4: Linux Base Driver for PRO/1000 Family of Adapters
In dynamic conservative mode, the InterruptThrottleRate value is set to 4000 for traffic
that falls in class "Bulk traffic". If traffic falls in the "Low latency" or "Lowest latency"
class, the InterruptThrottleRate is increased stepwise to 20000. This default mode is
suitable for most applications.
For situations where low latency is vital such as cluster or grid computing, the algorithm
can reduce latency even more when InterruptThrottleRate is set to mode 1. In this
mode, which operates the same as mode 3, the InterruptThrottleRate will be increased
stepwise to 70000 for traffic in class "Lowest latency".
Setting InterruptThrottleRate to 0 turns off any interrupt moderation and may improve
small packet latency, but is generally not suitable for bulk throughput traffic.
WARNING: If you are using the Intel(R) PRO/1000 CT Network Connection
(controller 82547), setting InterruptThrottleRate to a value greater than 75,000,
may hang (stop transmitting) adapters under certain network conditions. If this
occurs a NETDEV WATCHDOG message is logged in the system event log.
In addition, the controller is automatically reset, restoring the network
connection. To eliminate the potential for the hang, ensure that
InterruptThrottleRate is set no greater than 75,000 and is not set to 0.
NOTE: When e1000 is loaded with default settings and multiple adapters are in
use simultaneously, the CPU utilization may increase non-linearly. In order to
limit the CPU utilization without impacting the overall throughput, we
recommend that you load the driver as follows:
modprobe e1000 InterruptThrottleRate=3000,3000,3000
This sets the InterruptThrottleRate to 3000 interrupts/sec for the first, second,
and third instances of the driver. The range of 2000 to 3000 interrupts per
second works on a majority of systems and is a good starting point, but the
optimal value will be platform-specific. If CPU utilization is not a concern, use
RX_POLLING (NAPI) and default driver settings.

Speed and Duplex Configuration

Three keywords are used to control the speed and duplex configuration. These
keywords are Speed, Duplex, and AutoNeg.
If the board uses a fiber interface, these keywords are ignored, and the fiber interface
board only links at 1000 Mbps full-duplex.
For copper-based boards, the keywords interact as follows:
The default operation is auto-negotiate. The board advertises all supported speed
and duplex combinations, and it links at the highest common speed and duplex
mode IF the link partner is set to auto-negotiate.
If Speed = 1000, limited auto-negotiation is enabled and only 1000 Mbps is
advertised (The 1000BaseT spec requires auto-negotiation.)
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