Network Driver Parameters

intr_blank_time and intr_blank_packets

Description

These parameters affect on-board network throughput and latency on SPARC systems.

If interrupt blanking is disabled, packets are processed by the driver as soon as they arrive, resulting in higher network throughput and lower latency, but with higher CPU utilization. With interrupt blanking disabled, processor utilization can be as high as 80–90 percent in some high-load web server environments.

If interrupt blanking is enabled, packets are processed when the interrupt is issued. Enabling interrupt blanking can result in reduced processor utilization and network throughput, but higher network latency.

Both parameters should be set at the same time. You can set these parameters by using the ndd command as follows:

# ndd -set /dev/eri intr_blank_time 0
# ndd -set /dev/eri intr_blank_packets 0

You can add them to the /etc/system file as follows:

set eri:intr_blank_time 0
set eri:intr_blank_packets 0

Default

Both parameters are enabled on SPARC systems with an eri driver.

Both parameters are disabled on SPARC systems with an hme driver.

Range

0 (disabled) or 1 (enabled)

Dynamic?

Yes

Validation

None

When to Change

The value of the interrupt blanking parameter is a trade-off between network throughput and processor utilization. If higher processor utilization is acceptable for achieving higher network throughput, then disable interrupt blanking. If lower processor utilization is preferred and higher network latency is the penalty, then enable interrupt blanking.

Commitment Level

Unstable