Re: net5501: FreeBSD ipfw and the elusive 75Mbps throughput

Andrew Atrens [[email protected]] wrote:
> BUGS
>      The vr driver always copies transmit mbuf chains into longword-aligned
>      buffers prior to transmission in order to pacify the Rhine chips.  If
>      buffers are not aligned correctly, the chip will round the supplied
>      buffer address and begin DMAing from the wrong location.  This buffer
>      copying impairs transmit performance on slower systems but cannot be
>      avoided.  On faster machines (e.g. a Pentium II), the performance
> impact
>      is much less noticeable.

This is not true for the version of the chip included with Soekris
and PC Engines boxes, nor is it true for the OpenBSD or FreeBSD drivers.

OpenBSD's vr driver has interrupt mitigation and hw vlan tagging that
FreeBSD does (did?) not. Both enable hw checksum capability for IPv4.