[Bug 235031] [em] em0: poor NFS performance, strange behavior

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=235031

--- Comment #28 from Eugene Grosbein <eugen at freebsd.org> ---
(In reply to Rick Macklem from comment #27)

Hardware-assisted TSO itself may be not useful in case of 1Gbps or less
linerate for multiple reasons: overwhelming horsepower of modern (and even
pretty old modern) amd64 CPUs, NFS mounts over UDP, extensive use of ipfw
nat/libalias for routed jails/guest virtual machines as libalias is not
compartible with TSO etc. So when not dealing with 40Gbps or faster hardware, I
choose to disable TSO per-interface and not fight against corresponding bugs.

As for NIC rings, even pretty old Intel Gigabit have tunnables to setup big
enough rings to not bother of this issue.

Again, even old Intel Gigabit NICs have multiple interrupt tunnables to setup
right timings for local traffic profile.

As for testing different client mount option sets, I'll try it later and
respond.

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