Sun Microsystems Ethernet MMF/UTP Adapter User Manual
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Sun PCI-Express Dual Gigabit Ethernet MMF/UTP Adapter Installation and User’s Guide • June 2006
lists the tunable e1000 driver parameters for Linux operating systems,
and describes their function.
TABLE C-1
Tunable e1000 Driver Parameters for Linux Operating Systems
Keyword
Description
FlowControl
Valid Range: 0-3 (0=none, 1=Rx only, 2=Tx only, 3=Rx&Tx)
Default: Read from the EEPROM
If EEPROM is not detected, default is 3.
This parameter controls the automatic generation (Tx) and response
(Rx) to Ethernet PAUSE frames.
RxDescriptiors
Valid Range: 80-4096
Default Value: 256
This value is the number of receive descriptors allocated by the driver.
Increasing this value allows the driver to buffer more incoming packets.
Each descriptor is 16 bytes. A receive buffer is also allocated for each
descriptor and can be either 2048, 4056, 8192, or 16384 bytes, depending
on the MTU setting. When the MTU size is 1500 or less, the receive
buffer size is 2048 bytes. When the MTU is greater than 1500 the receive
buffer size will be either 4056, 8192, or 16384 bytes. The maximum MTU
size is 16114.
RxIntDelay
Valid Range: 0-65535 (0=off)
Default Value: 128
This value delays the generation of receive interrupts in units of 0.8192
microseconds. Receive interrupt reduction can improve CPU efficiency
if properly tuned for specific network traffic. Increasing this value adds
extra latency to frame reception and can end up decreasing the
throughput of TCP traffic. If the system is reporting dropped receives,
this value may be set too high, causing the driver to run out of available
receive descriptors.
TxDescriptors
Valid Range: 80-4096
Default Value: 256
This value is the number of transmit descriptors allocated by the driver.
Increasing this value allows the driver to queue more transmits. Each
descriptor is 16 bytes.
XsumRX
Valid Range: 0-1
Default Value: 1
A value of 1 indicates that the driver should enable IP checksum offload
for received packets (both UDP and TCP) to the adapter hardware.