Data Sheet

Inline Functions—Ethernet Controller I210
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Note: In the I210 the interval granularity is 1 s so some of the LSB bits of the interval are used for
the low latency interrupt moderation.
For example, if the interval is programmed to 125d, the network controller guarantees the CPU is not
interrupted by the network controller for at least 125 s from the last interrupt. In this case, the
maximum observable interrupt rate from the adapter should not exceed 8000 interrupts/sec.
Inversely, inter-interrupt interval value can be calculated as:
inter-interrupt interval = (1 * 10
-6
sec x interrupt/sec)
-1
The optimal performance setting for this register is system and configuration specific.
The Extended Interrupt Throttle Register should default to zero upon initialization and reset. It loads in
the value programmed by the software after software initializes the device.
When software wants to force an immediate interrupt, for example after setting a bit in the EICR with
the Extended Interrupt Cause Set register, a value of 0 can be written to the Counter to generate an
interrupt immediately. This write should include re-writing the Interval field with the desired constant,
as it is used to reload the Counter immediately for the next throttling interval.
The I210 implements interrupt moderation to reduce the number of interrupts software processes. The
moderation scheme is based on the EITR (Interrupt Throttle Register). Each time an interrupt event
happens, the corresponding bit in the EICR is activated. However, an interrupt message is not sent out