Sun Microsystems GigaSwift Ethernet Adapter manual PCI Bus Interface Parameters

TABLE 4-8RX Random Early Detecting 8-Bit Vectors

Field Name	Values	Description
red_dv6to8k	0 to 255	Random early detection and packet drop vectors for
		when FIFO threshold is greater than 6,144 bytes and
		fewer than 8,192 bytes. Probability of drop can be
		programmed on a 12.5 percent granularity. For
		example, if bit 8 is set, the first packet out of every
		eight will be dropped in this region. (Default=0)
red_dv8to10k	0 to 255	Random early detection and packet drop vectors for
		when FIFO threshold is greater than 8,192 bytes and
		fewer than 10,240 bytes. Probability of drop can be
		programmed on a 12.5 percent granularity. For
		example, if bit 16 is set, the first packet out of every
		eight will be dropped in this region. (Default=0)
red_dv10to12k	0 to 255	Random early detection and packet drop vectors for
		when FIFO threshold is greater than 10,240 bytes and
		fewer than 12,288 bytes. Probability of drop can be
		programmed on a 12.5 percent granularity. For

example, if bit 24 is set, the first packet out of every eight will be dropped in this region. (Default=0)

PCI Bus Interface Parameters

These parameters allow you to modify PCI interface features to gain better PCI interperformance for a given application.

TABLE 4-9PCI Bus Interface Parameters

ParameterDescription

tx_dma_weight Determines the multiplication factor for granting credit to the TX side during a weighted round robin arbitration. Values are 0 to 3. (Default=0) 0 means no extra weighting. The other values are power of 2 extra weighting, on that traffic. For example if tx_dma_weight

=0 and rx_dma_weight = 3, then as long as RX traffic is continuously arriving its priority will be 8 times greater than TX to access the PCI

44 Sun GigaSwift Ethernet Adapter Installation and User’s Guide • August 2004