Performance Related Issues

The driver works but the transmit and/or receive data rates are not optimal.

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These recommendations may assist with gaining immediate improvement:

1. Confirm PCI link negotiated uses its maximum capability

2. Stop the IRQ Balancer service:

   /etc/init.d/irq_balancer stop

3. Start mlnx_affinity service:

   mlnx_affinity start

For best performance practices, please refer to the "Performance Tuning Guide for Mellanox Network Adapters".

Out of the box throughput performance in Ubuntu14.04 is not optimal and may achieve results below the line rate in 40GE link speed.

IRQ affinity is not set properly by the irq_balancer

For additional performance tuning, please refer to Performance Tuning Guide.

UDP receiver throughput may be lower than expected, when running over mlx4_en Ethernet driver.

This is caused by the adaptive interrupt moderation routine, which sets high values of interrupt coalescing, causing the driver to process large number of packets in the same interrupt, leading UDP to drop packets due to overflow in its buffers.

Disable adaptive interrupt moderation and set lower values for the interrupt coalescing manually.

ethtool -C <eth>X adaptive-rx off rx-usecs 64 rx-frames 24

Values above may need tuning, depend- ing the system, configuration and link speed.