Sun Microsystems Gigabit Ethernet MMF/UTP Adapter manual

TABLE C-1lists the tunable e1000 driver parameters for Linux operating systems, and describes their function.

TABLE C-1Tunable 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.

84 Sun PCI-Express Dual Gigabit Ethernet MMF/UTP Adapter Installation and User’s Guide • June 2006