[CFT] alc(4) QAC AR816x/AR817x ethernet controller support

[Nils Beyer]

Hi,

Yonghyeon PYUN wrote:
> Default interrupt moderation policy is targeted to reduce latency
> so it will generate up to 10k interrupts/sec under high network
> load.  If you want to reduce number of interrupts/sec, tune
> interrupt moderation sysctl variables mentioned in alc(4).

Tried several values here:

	dev.alc.0.int_rx_mod={1000,10000,100000}
	dev.alc.0.int_tx_mod={1000,10000,100000}

but didn't notice any changes neither in CPU usage nor throughput during the
"iperf" test; "kernel{alc0 taskq}" stays at 70-75%. I've downed/upped the
interface "alc0" after every change.

A simple iSCSI test using the native CTL interface works really well. A "fio"
test results in 100MB/s read and write. Double-checking using "netstat -I"
confirms gigabit-line speeds at around 120MB/s.
CPU usage at "kernel{alc0 taskq}" is as high as in the "iperf" test. So I think
that's a limitation of the AR8161 chip.


> Updated the diff to address link establishment issue.
> http://people.freebsd.org/~yongari/alc/pci.quirk.diff
> http://people.freebsd.org/~yongari/alc/alc.diff.20141001

Confirmed; with the anti-hibernation patch, link estalishment is now working
flawlessly.

Thank you very much for your work...



Regards,
Nils