IPv6 throughput only half of IPv4 on ERL

[Wolfgang Zenker]

* Adrian Chadd <adrian at freebsd.org> [150208 17:17]:
> everything's bigger in ipv6?

true, but its bigger on other platforms as well :-)

> Well, try kldload hwpmc and see if pmcstat works for you. I haven't
> tried it on the Octeon hardware. That'll be useful for chasing down
> why it's chewing CPU.

I built a kernel with device hwpmc built in, but so far not much success
getting it to do anything except killing the machine.
In dmesg I find this line:
hwpmc: SOFT/16/64/0x67<INT,USR,SYS,REA,WRI> OCTEON/2/64/0x1ff<INT,USR,SYS,EDG,THR,REA,WRI,INV,QUA>
so hwpmc seems to be indeed to be available.

As I have no clue so far how to use pmcstat, I tried one of the example
commands from the man page (pmcstat -S instructions -O /tmp/sample.out)
which resulted in
cpu:1-Trap cause = 2 (TLB miss (load or instr. fetch) - kernel mode)
panic: trap
cpuid = 1
followed by automatic reboot. Maybe hwpmc is not usable on this platform
so far.

Wolfgang