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

[Yonghyeon PYUN]

On Wed, Oct 01, 2014 at 11:14:59AM +0200, Nils Beyer wrote:
> 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.
> 

You may see difference when H/W handles tiny grams(i.e. 64 bytes
UDP frames).  For bulk TCP/UDP transfers, alc(4) can easily
saturate the link.

> 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...

Thanks for your testing.  Patch updated again to fix wrong lock
assertion.
http://people.freebsd.org/~yongari/alc/alc.diff.20141002