Ethernet Support Guide (for HP-UX 11i v1, 11i v2)

Administration
Gigabit-Specific Information
Chapter 3
44
Speed Example:
To set the speed to 100 Mbit/s full-duplex on 1000Base-T, enter:
$ lanadmin -X 100fd ppa
NOTE The lanadmin -S option to set the speed is not supported on Gigabit Ethernet.
Stats Clear Example:
To clear all driver and card statistics, enter:
$ lanadmin -X stats clear ppa
Buffer Coalescing Threshold Example:
To set the send buffer coalescing threshold, enter:
$ lanadmin -X send_max_bufs 32 ppa
Note that the send_max_bufs tuning option requires the additional option 32 (the
coalescing threshold).
Interrupt Coalescing Ticks Example:
To set the send interrupt coalescing ticks, enter:
$ lanadmin -X send_coal_ticks 2000 ppa
Note that the send_coal_ticks tuning option requires the additional option 2000 (the
number of coalescing ticks).
Performance and Tuning Considerations
The following parameters can be adjusted to improve Ethernet performance:
• Send Buffer Coalescing Threshold
• Receive Buffer Coalescing Threshold
• Send Interrupt Coalescing Ticks
• Receive Interrupt Coalescing Ticks
CAUTION These features are for advanced users. If you set these parameters and you do not
understand what they do, you may have unpredictable results. HP recommends that you
use the default settings.
When the card transmits or receives a frame, the system must be notified of the event. If
the card interrupts the system for each transmitted and received frame, the result is a
high degree of processor overhead. To prevent that, Gigabit Ethernet provides a feature
called interrupt coalescence. Effective use of this feature can reduce system overhead
and improve performance.
Interrupt coalescence essentially means that the card interrupts the system after
sending or receiving a few frames. The number of frames after which the card interrupts
the processor can be tuned independently for both send and receive. The tuning can be
specified via two parameters each for send and receive, so there is a total of four