Gigabit Ethernet-SX PCI Adapter Device Driver (14100401)

The Gigabit Ethernet-SX PCI Adapter Device Driver (14100401) supports the following additional configuration parameters:

Software Transmit Queue Size

Indicates the number of transmit requests that can be queued for transmission by the device driver. Valid values range from 512 through 16 384.

Transmit Jumbo Frames

When you set the attribute value to Yes, frames up to 9018 bytes in length can be transmitted on this adapter. When you set the attribute value to No, the maximum size of frames transmitted is 1518 bytes. Frames up to 9018 bytes in length can always be received on this adapter.

Enable Hardware Checksum Offload

When you set the attribute value to Yes, the adapter calculates the checksum for transmitted and received TCP frames. When you set the attribute value to No, the checksum is calculated by appropriate software.

Note: The mbuf structure, which describes a transmitted frame, contains a flag that indicates whether the adapter calculates the checksum for the frame.

Media Speed

The Gigabit Ethernet-SX PCI Adapter Device Driver (14100401) supports a user-configurable media speed only for the IBM® 10/100/1000 Base-T Ethernet PCI adapter (feature 2975). For the Gigabit Ethernet-SX PCI Adapter (feature 2969), the only possible choice is autonegotiation. The media speed attribute indicates the speed at which the adapter attempts to operate. The available speeds are 10 Mbps half-duplex, 10 Mbps full-duplex, 100 Mbps half-duplex, 100 Mbps full-duplex and autonegotiation, with a default of autonegotiation. Select autonegotiate when the adapter should use autonegotiation across the network to determine the speed. When the network does not support autonegotiation, select the specific speed.

Note: The autonegotiation setting must be selected in order for the adapter to run at 1000 M-bit/s.

Enable Hardware Transmit TCP Resegmentation

When you set the attribute value to Yes, the adapter performs TCP resegmentation on transmitted TCP segments. With this capability, TCP/IP can send larger datagrams to the adapter, which can increase performance. When you set the attribute value to No, TCP resegmentation is not performed.

The following configuration parameters for the Gigabit Ethernet-SX PCI Adapter Device Driver (14100401) are not accessible using SMIT. You can modify them only using the chdev command.

stat_ticks

Indicates the number of microseconds that the adapter waits before updating the adapter statistics (through a DMA write) and generating an interrupt to the host. Valid values range from 1000 through 1 000 000. The default value is 1 000 000.

receive_ticks

Indicates the number of microseconds that the adapter waits before updating the producer index of the receive return ring (through a DMA write) and generating an interrupt to the host. Valid values range from 0 through 1000, the default value is 50.

receive_bds

Indicates the number of receive buffers that the adapter transfers to host memory before updating the producer index of the receive return ring (through a DMA write) and generating an interrupt to the host. Valid values range from 0 through 128. The default value is 6.

tx_done_ticks

Indicates the number of microseconds that the adapter waits before updating the send consumer index (through a DMA write) and generating an interrupt to the host. Valid values range from 0 through 1 000 000. The default value is 1 000 000.

tx_done_count

Indicates the number of transmit buffers that the adapter transfers from host memory before updating the send consumer index (through a DMA write) and generating an interrupt to the host. Valid values range from 0 through 128. The default value is 64.

receive_proc

When this number of receive buffer descriptors is processed by the device driver (or all packets are received), the device driver returns this number of receive buffer descriptors to the adapter through an MMIO write. Valid values range from 1 through 64. The default value is 16.

rxdesc_count

When this number of receive buffer descriptors is processed by the device driver (or all packets were received), the device driver exits the rx_handler() routine and continues processing other adapter events, such as transmit completions and adapter status changes. Valid values range from 1 through 1 000 000. The default value is 1000.

slih_hog

Indicates the number of adapter events (such as receive completions, transmit completions and adapter status changes) that are processed by the device driver per interrupt. Valid values range from 1 through 1 000 000. The default value is 10.

copy_bytes

When the number of data bytes in a transmit mbuf structure exceeds this value, the device driver maps the mbuf data area into DMA memory and updates the transmit descriptor so that it points to this DMA memory area. When the number of data bytes in a transmit mbuf structure does not exceed this value, the data is copied from the mbuf structure into a preallocated transmit buffer that is already mapped into DMA memory. The device driver also attempts to coalesce transmit data in an mbuf chain into a single preallocated transmit buffer until the total transmit data size exceeds that of the preallocated buffer (2048 bytes). Valid values range from 64 through 2048. The default value is 2048.