Allied Telesis AT-2931SX, AT-2916SX manual ˆ rxjumbodesccnt, ˆ adaptivecoalesce, ˆ rxcoalesceticks

AT-29xx Series Gigabit Ethernet Network Adapters Installation Guide

Setting this parameter higher allows the NIC to buffer larger bursts of network traffic without dropping frames, especially on slower systems. Note that the driver may not be able to allocate the required amount of memory if this parameter is set too high. This parameter should not be set less than 50 if adaptive_coalesce (see below) is enabled.

ˆrx_jumbo_desc_cnt

Configures the number of receive descriptors for jumbo frames larger than 1528 bytes. The default is 128 and the valid range is from 1 to

255.When jumbo frames larger than 1528 bytes are used, do not set this parameter to lower than 60 on systems with high network traffic. Setting this parameter higher allows the NIC to buffer larger bursts of jumbo traffic without dropping frames, especially on slower systems. Depending on kernel and system architecture, the driver may require up to 268 bytes per descriptor. Note that each descriptor also requires a buffer the size of a maximum jumbo frame. On systems with insufficient memory, it may be necessary to reduce this parameter. This parameter should not be set to less than 50 if adaptive_coalesce (see below) is enabled. When the maximum frame size is less than 1528 (MTU size less than 1514), this parameter is not used and is always 0.

ˆadaptive_coalesce

Enables or disables adaptive adjustments to the various interrupt coalescing parameters. Enabling it allows the driver to dynamically adjust the interrupt coalescing parameters to achieve high throughput during heavy traffic and low latency during light traffic. Do not set rx_std_desc_cnt (and rx_jumbo_desc_cnt if using jumbo frames) to less than 50. Also, do not set tx_pkt_desc_cnt to less than 80 when this parameter is enabled. Choose from the following selections:

–0 - disabled

–1 - enabled (default)

ˆrx_coalesce_ticks

Configures the number of 1 usec ticks before the NIC generates receive interrupt after receiving a frame. This parameter works in conjunction with the rx_max_coalesce_frames parameter. Interrupt is generated when either of these thresholds is exceeded. A value of 0 means this parameter is ignored and an interrupt is generated when the rx_max_coalesce_frames threshold is reached. The valid range is from 0 to 500 and default is 80. This parameter is not used and is adjusted automatically if adaptive_coalesce is set to 1.

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