sys_attrs_alt(5)sys_attrs_alt(5)NAMEsys_attrs_alt - alt subsystem attributes
DESCRIPTION
This reference page lists and describes attributes for the alt (alt)
kernel subsystem. This subsystem is used by the DEGPA Gigabit Ethernet
network interface cards (NICs). The hardware and firmware for these
cards support coalescing, a threshold that causes the driver to send an
interrupt to the kernel. This threshold can be defined in terms of a
timer or the number of packets sent or received. The *_coal and *_ticks
attributes in the following list support performance tuning related to
coalescing.
Refer to sys_attrs(5) for an introduction to the topic of kernel sub‐
system attributes.
The version number of the alt driver. This is a read-only
attribute, and cannot be changed.
The version number of the firmware that is downloaded to the
DEGPA Gigabit Ethernet card. This is a read-only attribute and
cannot be changed.
A value that enables (1) or disables (0) the awakening of sepa‐
rate threads by the driver's interrupt service routine to handle
completion of transmit and receive operations. When separate
worker threads are enabled, the system load of the Gigabit Eth‐
ernet driver can be spread over multiple CPUs. When separate
worker threads are disabled, the master system CPU (or the mas‐
ter CPU in each RAD of a NUMA system) services all the transmit
and receive operations for the system's DEGPA Gigabit Ethernet
adapters.
Default: 1 (multiple threads enabled)
A 0 setting improves the performance of the driver software
itself. However, overall system performance is likely to suffer
during times of high network load because kernel applications
other than the driver can have difficulty accessing the master
CPU. Furthermore, the likelihood of overall system performance
degradation goes up with each additional DEGPA Gigabit Ethernet
card supported by the system. For this reason, the default set‐
ting (1) is recommended for most systems and applications.
The number of packets that are sent before an interrupt is gen‐
erated (assuming that the recv_ticks timer does not expire
first).
Default: 32 (packets)
Minimum: 0
Maximum: 511
The receive DMA burst size (in longwords) for the DEGPA Gigabit
Ethernet card. The default value (0) specifies that the receive
DMA burst size is set to be the maximum supported by the Gigabit
Ethernet card.
Although this attribute can be modified at run time, do not
change it unless instructed to do so by support personnel or
patch kit instructions.
The number of microseconds (usec) between the receipt of the
last packet and the generation of an interrupt (assuming that
the recv_coal threshold is not reached first).
Default: 200 (usec)
Minimum: 0
Maximum: 888,888
The number of packets that are sent before an interrupt is gen‐
erated (assuming that the send_ticks timer does not expire
first).
Default: 32 (packets)
Minimum: 0
Maximum: 511
The number of microseconds (usec) between the transmission of
the last packet and the generation of an interrupt (assuming
that the send_coal threshold is not reached first).
Default: 200 (usec)
Minimum: 0
Maximum: 888,888
The number of microseconds (usec) between statistics updates
from the adapter to the host.
Default: 1000000 (usec), or 1 second
Minimum: 1
Maximum: 10000000
The transmit DMA burst size (in longwords) for the DEGPA Gigabit
Ethernet card. The default value (0) specifies that the transmit
DMA burst size is set to be the maximum supported by the Gigabit
Ethernet card.
Although this attribute can be modified at run time, do not
change it unless instructed to do so by support personnel or
patch kit instructions.
SEE ALSOsys_attrs(5)sys_attrs_alt(5)
